Medical Imaging Technique and Procedures

Medical Imaging Technique and Procedures Medical Imaging Technique and Procedures

Alfonce Mang’oka Nyalla

Acrodile Publishing Ltd Medical Imaging Technique and Procedures

All rights reserved. No part of this book may be used or reproduced by any means, graphic, electronic, or mechanical, including photocopying, recording, taping or by any information storage retrieval system without the written permission of the publisher except in the case of brief quotations embodied in critical articles and reviews.

Acrodile Publishing Limited P.O.Box 15298-00509, Lang’ata-Nairobi, Kenya Email: [email protected] Website: www.acrodile.co.ke

ISBN 978-9966-007-34-6

Typeset by Medlar Publishing Solutions Pvt Ltd, India Contents

Forward xi

Chapter 1 Medical Imaging Techniques and Procedures 1 Objectives 1 Medical Imaging 1 Medical Imaging Modalities 2 Branches in Imaging 2 Considerations in Imaging 2 Ethics 2 Effects of Ionizing Radiation 3 Somatic effects 3 Genetic effects 3 Radiation Protection 3 Upper Limbs 4 Shoulder girdle 4 Imaging Technique 4 Hand 4 PA and oblique 4 Oblique 4 Ball catching PA oblique 5

Hand Oblique Projection 5 Fingers 5 Thumb 6 Index and middle finger 6 Ring and 5 th fingers 6 Wrist joint 6 Scaphoid views 7 Carpal Tunnel 7 Forearm 8 Elbow joint 8 Ulnar groove 8 Transthoracic 8 Humerus 8 Lower Limb 9 Foot 9 Toes 9 Ankle joint 9 Tibia and fibula 10 Knee 10 Patella 11 Femur 11 Shoulder Girdle 11 Shoulder joint 11 Scapula 12 Acromio-clavicular joints and clavicle 12 Clavicle 12 Pelvic girdle 12 Pelvis 12 Hip joint 12 Vertebral Column 14 Cervical 14 Thoracic vertebrae 14 Lumbar vertebrae 14 Sacro – Iliac Joints 15 Chest 15

vi Acute Abdomen 17 AP supine 17 Dorsal decubitus 18

Chapter 2 Medical Imaging Techniques and Procedures of Skull, Teeth, FBs and High Kilovoltage Technique 19 Objectives 19 Skull Imaging 19 Radiographic base line (RBL) 19 Anthropological line 20 Coronal 20 Interpupilary line 20 Equipment 20 Patient preparation 20 Indications 20 Cranium 20 Basic views 20 Supplementary views 20 Base of skull 22 Pituitary fossa 22 Jugular foramina 22 Facial bones 22 Occipito-mental (OM) 22 Mandible 23 Dental Imaging 24 WHO dental formulae 24 Types of dentistry imaging 25 Orthopantomography (OPG) 25 Land marks 25 Equipment 25 Patient preparation and indications 25 Centring points 26 Occlusal views 26 Bite wing views 26

Orthopantomography (OPG) 27 Radiation protection 27 High Kilovoltage (KV) Imaging 28 Objectives 28 Advantages 28 Disadvantages 28 Applications 28 Foreign bodies-FBs 29 Types of FBs 29 Imaging procedure 29 Sinuses and Fistulae 30 Sinus 30 Fistula 30 Fistulography 30 Faecal fistula 30 Pediatric Imaging 31

Chapter 3 Medical Imaging Techniques and Procedures Using Contrast Media and Mobile Examinations or Portable 33 Contrast Examinations 33 Alimentary Tract Examinations 34 Barium studies 34 Examinations of GIT 34 Responsibilities and duties of radiographer 34 Barium swallow 35 Barium meal 36 Barium follow through 37 Barium enema 38 Contrast medium 39 Small bowel enema 43 Urinary System 47 Patient preparation 47 Indications for IVU 47 Equipment and accessories 47 Retrograde pyelography or ascending pyelography 48

Reproductive System 49 Nervous System 50 Myelography 50 Circulatory System 51 Interventional radiology 51

Chapter 4 Medical Imaging Techniques and Procedures – Modern Modalities 53 Objectives 53 Ultrasound 53 Transducer 54 Ultrasound Terms 54 Production of ultrasound 54 Transducers 55 Display Modes 55 Types of transducers 55 Knobology 55 Major Examinations 56 Abdomen 56 Small parts 57 Indications 57 Gynaecological 57 Obstetric indications 57 Computerized Tomography – CT 58 Objectives 58 Computerized tomography 58 CT terms 58 CT equipment 59 CT generations 60 Scanning procedure 60 Display/archive 61 CT image formation 61 Image quality 62 Advantages 62 Computed Radiography (CR) 62 Principles of computed radiography 62

Advantages of CR 63 Disadvantages of CR 63 Digital Radiography (DR) 63 CR verses DR 64 Benefits of CR and DR 64 Medical applications of CR and DR 64 Industrial applications 64 Photostimulable phosphor (PSP) 65 Image contrast 65 Nuclear Medicine 65 Objectives 65 Definition 66 Classification 66 Radiotherapy 68 Objectives 68 Definition 68 Reasons for therapy 68 Branch therapy 68 Teletherapy 68 Applications 69 Magnetic Resonance Imaging (MRI) 69 Objectives 69 Definition 69 Equipment 69 Applications 70 Operation 70 Images 70 Contrast media 71 MRI coils 71 Hardware 71 Magnets for MRI 71 Quench 72 Advantages of superconducting magnets 72

References 73 Forward

This book is intended to fill a gap in the lack of books and more so local ones for the training and reading in Medical Imaging Sciences especially in medical imaging techniques and procedures. The subject in medical imaging called Imaging and Therapeutic Modalities (ITM) is more deserving. This is a core subject in which students and radiographers gain knowledge, skills and attitude in imaging and therapeutic procedures to assist them carry out diagnostic and therapeutic procedures for patients needing these examinations in the hospitals.

The book will be of more value to all students undertaking training in Medical Imaging, Radiographers and any other medical professional with an interest in medical imaging.

This book covers the wealth of experience of the author; who has been teaching in the department of Medical Imaging Sciences (MIS) in Kenya Med- ical Training College (KMTC) for the last thirty one years with ITM as one of the main subjects. Notes have been compiled for a long time but the last two years have been dedicated to the writing of this very vital book to assist the users. Chapter 1 Medical Imaging Techniques and Procedures

 Objectives • Topical outline • Imaging • Modalities • Branches • Considerations • Ethics • Radiation protection • Image quality • Upper limbs • Lower limbs • Shoulder girdle • Pelvic girdle • Spine • Chest • Abdomen.

 Medical Imaging The science of taking images for diagnostic purposes – The old name is Radi- ography which does not embrace all the imaging modalities. This meant that X-rays were used to produce images on the film which was finally called radiograph and no other energies like Ultrasound, Magnetism (MRI) and radioisotopes could be used.

 Medical Imaging Modalities The modalities are six, namely:

1. Conventional imaging using X-rays 2. Ultrasonography using sound waves 3. Computerized Tomography uses X-rays 4. Magnetic Resonance Imaging using magnetism 5. Nuclear Medicine using radio nuclides and 6. Radiotherapy using gamma rays and X-rays which is a therapeutic procedure.

 Branches in Imaging 1. Medical 2. Veterinary and 3. Industrial Imaging.

 Considerations in Imaging • Patient identity • Waiting time • Preparation: Psychologically, physically and physiologically • Privacy • Comfort, Hygiene • Immobilization • Care – before, during and after the exam • Consent • Procedure explanation • Equipment – sound.

 Ethics The dos’ and don’ts’ when dealing with a patient are: • No request form no imaging • No consent when needed no imaging • No imaging under intoxication

• No abuse or confrontation with patient • Radiation protection • Privacy of patient • Prior patient preparation • Records kept • Integrity • Prevent cross infection • Explain procedure.

 Effects of Ionizing Radiation Ionizing radiation has harmful effects. The only modalities without ionizing radiation effects are MRI and ultrasound although the latter may have thermal effects on an un born child. These effects are Somatic and Genetic.

Somatic effects These affect the person who is irradiated and include: hair loss, eye cataract, erythema, still birth, abortion, nausea, vomiting, cell death and leukemia among others.

Genetic effects They manifest in the offspring and entail body deformities due to gonad cells damage of the parent. The deformities and mutations may involve loss of body parts like limbs.

 Radiation Protection This is done by practicing the following: • Beam collimation • Fast screens and films-high speed • Meticulous technique • Proper instructions • Patient identification • Short exposures • Inverse square law • Doors closed • Few people in the room • Do not use faulty equipment • Use of protective materials • Minimize use of ionizing radiation • All this is for self, staff, patient and the public at large.

 Upper Limbs The upper limb:

Shoulder girdle Consists of Scapula, clavicle and the arm consisting of humerus, forearm (radius and ulna), 8 carpal bones, 5 metacarpals and 14 phalanges. The joints are shoulder, elbow, wrist, carpo-metacarpal, metacarpo-phalangeal and inter-phalangeal.

 Imaging Technique There are mandatory views or projections thus: • Basic views antero-posterior and lateral • Supplementary or additional views • Alternative views when the basic projections are impossible example the chest AP instead of PA for very sick patients, children or in theatre or the ward.

 Hand PA and oblique Hand is for grasping and formed by phalanges and carpals. On a 24×18 cm, hand in pronation. Fingers extended. Centre to the head of 3rd metacarpal. Collimate beam and FFD is 100 cm.

Oblique Hand 45 degrees from pronation, fingers curved and supported on foam pad. Centre to the head of 3rd metacarpal and FFD 100 cm. Lateral may be done for bone displacement and same film used. Ball catching PA oblique

Figure 1.1 This demonstrates rheumatoid arthritis.

 Hand Oblique Projection Fingers Are formed by the 14 phalanges each digit with three phalanges except the thumb which has two and the projections are PA and Lateral.

Postero-anterior (PA) The hand lies on a cassette with extended fingers and hand in pronation. 24×18 cm cassette/film used. Focus Film Distance FFD is 100 cm. Centre over the head of proximal phalanx of 3rd finger and collimate beam to the area of interest.

Lateral Hand and forearm rotated 90 degrees, thumb rests on a foam pad. Centre over the head of 1st phalanx or proximal of index finger. FFD is 100 cm, film 24×18 cm and beam collimated. To show bone displacement if fracture present. Thumb Postero-Anterior: Hand in lateral 90 degrees from pronation, thumb rests on a foam pad. 24×18 cm cassette used FFD 100 cm. Centre to the metacarpo-phalangeal joint.

Lateral Hand in pronation, palm slightly raised on foam pad. Centre to the metacarpo-phalangeal joint.

Alternative Latero-medial thumb perpendicular to film for lateral and AP inward and outward posterior part on film.

Index and middle finger Lateral Hand rotated inward until lateral of index in contact with the film, the rest of fingers flexed. Centre over the head of 1st phalanx of index finger. Film 24×18 cm and FFD 100 cm. The other portion of film used for the PA which is same as hand with restriction to the two digits.

Ring and 5th fingers Latero – Medial aspect of the fingers in contact with 24×18 cm cassette, rest flexed and thumb on foam pads. Centre to the head of 1 st phalanx of ring finger. PA as of hand with beam restricted to the fingers and same film.

Wrist joint Formed by scaphoid, lunate, triquetral, radius and ulna. Ulna isolated by a fibro-cartilage. Wrist bones medio-lateral are Pisiform, Triquetral, Lunate and scaphoid proximally. Distally latero-medial is Trapezium, Trapezoid, Capitate and Hamate. Capitate is the largest and first to ossify, lunate half moon and likely to be dislocated. Scaphoid is the most frequently fractured. Views are PA and Lateral.

Postero-anterior Wrist on a 24×18 cm cassette in pronation, patient besides the X-ray couch, elbow flexed. Centre between the styloid processes of radius and ulna. Lateral Elbow flexed and wrist at 90 degrees. Centre to lateral styloid process. For Colles fracture and displaced epiphyses-ulnar deviation. Colles fracture is a fracture of the distal radius which may be difficult to heal hence calling for fixation of metal plates or nailing.

Scaphoid views Four views used: • PA as normal wrist • Lateral as wrist • PA ulnar deviation as PA but hand rotated outward or laterally • PA or AP oblique.

 Carpal Tunnel Formed by depression of carpal bones. Nerves, vessels and ligaments pass here and carpal tunnel syndrome occurs which is neurological. An axial view is done with patient sitting backwards fingers on the film.

Figure 1.2 Wrist joint showing Colles fracture PA and Lateral. Forearm Antero-posterior Forearm on supination and elbow extended. 24×30 cm cassette used. Centre to middle of forearm. FFD 100 cm and beam collimated.

Lateral From supination 90 degrees rotation. Elbow is flexed. Centre to the middle of forearm.

Elbow joint Formed by Trochlea and Capitellum of humerus linking with Trochlear notch of ulna and head of radius.

Antero-posterior Forearm and arm supinated, joints extended-Centre 2.5 cm below midpoint of epicondyles using FFD 100 cm and 24×30 cm cassette.

Lateral Elbow 90 degrees flexion, arm and forearm same plane. Joint 90 degrees from supination. Centre to the lateral epicondyle.

Ulnar groove This is a groove to medial humeral epicondyle. Passage of ulnar nerve. Ulnar called funny bone because of the sensations from the nerve. Patient sits backwards, elbow 45 degree flexion. Centre to lateral part of medial epicondyle. FFD 100 cm, 24×18 cm cassette and beam collimated.

Transthoracic Elbow strapped on chest – Centre through the chest. Avoided because of high radiation dose to the patient.

Humerus Antero-posterior Patient lies on the X-ray couch. Arm abducted and elbow extended. 40×15 cm cassette used. FFD 100 cm, beam collimated. Centre between the joints or middle of cassette. Both joints included or one near the injury not to miss a fracture or dislocation. The upper arm is the humerus and lower is the forearm or radius and ulna.

Lateral From supination, the humerus is rotated 90 degrees with flexed elbow. Centre as for AP.

 Lower Limb Has lower and upper part. Consists of femur, patella, tibia, fibula, tarsals (7), metatarsals (5) and 14 phalanges. Called leg with upper and lower leg.

Foot Made of tarsals, metatarsals and phalanges.

Dorsi-plantar oblique Patient steps on a 30×24 cassette, foot rotated 45 degrees medially. Centre through cuboid-navicular area. FFD 100 cm and beam collimated to area of interest.

Dorsi-plantar Patient sits on the couch, foot on cassette, knee medial rotation. Centre through cuboid – navicular region. Lateral can be done for foreign body (FB), Flat foot weight bearing. This condition is called Pes Planus. Calcaneal spur is a bone growth on the calcaneus which is very painful – lateral view in weight bearing done for both calcani for comparison.

Toes Dorsi-plantar, dorsi plantar oblique and lateral as for the foot but centering to the toe of interest. Sub-talar joints also the same. March fracture may occur along the metatarsals common with marching soldiers.

Ankle joint Hinge synovial joint formed by talus and distal tibia and fibula. Antero-posterior (AP) Patient sits on the X-ray couch; leg extended and foot medial rotation to make malleoli equidistant from the cassette. FFD 100 cm, 24×30 cm cassette used. Foot is vertical. Centre between the malleoli.

Lateral Patient is rotated to injured side. Ankle joint and knee in contact with cassette. Malleoli superimposed. Centre to medial malleolus. Stress views could be done. This is applied by the surgeon. Potts fracture may occur along distal tibia.

Tibia and fibula Normally called lower leg. AP and lateral done. AP – Patient sits on the couch, knee extended, malleoli equidistant, 30×40 cassette used. Centre to middle of leg and include joint near point of injury if not all joints.

Lateral Patient (Pt) is rotated to injured side, knee flexed, malleoli superimposed. Centre to middle leg. Horizontal beam used on patients on traction. FFD 100 cm and same cassette used as in AP projection.

Knee Synovial hinge joint formed by femoral condyles, tibia and posterior aspect of patella.

Antero-posterior Patient sits on the X-ray couch, knee extended, foot vertical and condyles equidistant from cassette, 24×18 cassette used, FFD 100 cm. Centre through the joint or 1 cm below apex of patella.

Lateral Patient rotated to injured side, Condyles superimposed, heel supported. Centre to medial condyle and collimate beam to area of interest. FFD 100 cm and cassette 24×18 cm. Patella A sesamoid bone from ligaments. Skyline view or infero-superior view done and lateral. Patient lies prone and knee at 90 degrees. Centre to inferior surface, tube angled 15 degrees cephalad that is beam towards the head. Tibial tubercle in Os Good Schlatters disease a lateral is done. This is degeneration of tibial tubercle. PA done prone. Intercondylar view for loose bodies in knee joint.

Femur Longest and strongest bone of the leg to bear the body weight.

Antero-posterior Patient lies supine, knee and hip extended, foot vertical and medial rotation to avoid neck foreshortening. FFD 100 cm, 15×40 cm cassette. Centre to middle of cassette and include all joints if not one near point of injury.

Lateral Patient is rotated to the affected side, condyles superimposed, centre to middle of femur or cassette. Sometimes horizontal beam is used when patient on traction or on weights.

 Shoulder Girdle Formed by 2 scapulae and 2 clavicles.

Shoulder joint Freely movable joint formed by glenoid cavity and humeral head. AP – Pt lies supine on the X-ray couch, elbow extended and scapula parallel to film, 24×30 cm cassette used FFD 100 cm. Centre to coracoid process or through the joint.

Axial view (Supero-Inferior) Patient sits beside X-ray couch, joint flat as possible. Curved cassette used if available (24×30 cm). Centre through the joint. Muscle calcifications AP done in external and internal rotation of arm. Stryker’s view This projection is to demonstrate recurrent subluxation of the shoulder joint. The hand is over the head. Centre through the coracoid process or the joint.

Scapula AP-Pt lies supine and rotated until scapula parallel to 24×30 cm cassette. Centre to humeral head. FFD 100 cm.

Lateral Pt prone and rotated 60–75 degrees. Centre to medial border of the scapula.

Acromio-clavicular joints and clavicle For children both joints done for comparison. Centre between the joints. Cassete 24×18 cm.

Clavicle AP done centring to middle of clavicle. FFD 100 cm and cassette 24×18 cm.

Pelvic girdle Attachment for lower limbs. Has 2 innominate bones. 3 bones Ischium, Ilium and Pubic bones to form acetabulum which receives head of femur to form hip joint.

Pelvis Formed by innominate bones. Posterior is coccyx and sacrum. AP done. Pt supine and pelvis symmentical A.S.I.S (Anterior Superior Iliac Spine) equidistant from the cassette. FFD 100 cm and 35×43 cm cassette used. Centre to midline 5 cm below A.S.I.S or 5 cm above upper border of symphysis pubis. Erect for weight bearing in subluxation weight on each leg. Symphysis pubis small aperture AP.

Hip joint Synovial joint of lower limb formed by head of femur and acetabulum of the pelvic bones. AP Pt supine, legs medial rotation. Pelvis symetrical. Centre to midline 2.5 cm above symphysis pubis. One hip centre to femoral pulse. FFD 100 cm and cassette 24×30 cm for one hip.

Lateral Pt is rotated to injured side knee and hip flexed. FFD 100 cm, cassette 24×30 cm, beam collimated. Centre to femoral pulse. Femoral neck true lateral is done using a horizontal beam.

Figure 1.3 Hip joint AP showing fractured neck of femur.

Von Rosen view This is for congenital hip dislocation or dysplasia. Hips rotated 45 degrees each. Centre to the midline at the level of femoral pulse. Occurs mostly in children. FFD 100 cm and cassette 24×30 cm. Frog position Pelvis symmetrical, hips, knees flexed and rotated externally. Centre as for Von Rosen view. This shows epiphyses. FFD 100 cm and cassette 24×30 cm.

 Vertebral Column Consists of 33 irregular bones as follows: Cervical 7, Thoracic 12, Lumbar 5, Sacral 5 and Coccygeal 4.

Cervical Difficult to demonstrate because of mandible and shoulders which obscure the vertebrae. AP – chin raised. Centre to sternal notch. Open mouth for 1–3. Lateral FFD 150 cm. Centre 2.5 cm below angle of mandible. Obligues for intervertebral foramina. Posterior show opposite side. Swimmers view for cervico-thoracic junction.

Thoracic vertebrae AP and Lateral. AP-Pt supine and pelvis symmetrical, knees and hips flexed. FFd 100 cm, cassette 15×43 cm. Centre to middle of cassette with beam collimation.

Lateral Pt rotated 90 degrees from supine, legs and hips flexed, foam pad under the spine to reduce lordosis. Centre to middle of cassette. Scoliosis (lateral spine curvature) and kyphosis (antero-lateral curvature) a larger film is used.

Lumbar vertebrae AP Patient supine, knees and hips extended, pelvis symmetrical, FFD 100 cm, film 24×30 cm. Centre to the midline at the level of lower costal margin.

Lateral Patient rotated 90 degrees from supine, joints flexed, Centre 2.5 cm anterior to the body of lumbar vertebra (L 3). FFD 100 cm, cassette 24×30 cm, foam pad under spine to reduce lumbar lodosis and beam collimated. Figure 1.5

Figure 1.4 AP and lateral lumbar spine. Lumbar vertebrae lateral projection.

Coned view For L5 S1. This is as lateral lumbar but centre to joint and cassette size 18×24 cm. It should be noted that lumbar vertebrae there are three basic views as described. Coccyx and Sacrum as for pelvis and beam collimated.

 Sacro – Iliac Joints S – Shaped joints difficult to demonstrate. Prone projection done and that is enough. Sometimes obliques are done for both sides. Ankylosing spondilitis is arthritis of the joints which fuse and cause a lot of pain. These views done for various traumatic and pathological reasons.

Chest This is the area from root of the neck to the diaphragm. AP and Lateral done for various infections. PA The patient stands facing a pedestal bucky, Chin raised, palms on the hips and shoulders down ward. FFD 150 cm, 43×35 cm cassette or 35×35 cm for women and other men. Centre to the midline at the level of midpoint of medial borders of scapulae-T4level of sternal angle. Exposure made on arrested inspiration. Lateral – Pt rotated 90 degrees from PA. Spine paral lel to cassette. FFD 150 cm, cassete 40×30 cm. Chin raised and arms over the head. Centre through the axilla at the level of T4 or to middle of cassette. Exposure is made on arrested inspiration. AP done as alternative and oblique additional. Posterior oblique shows ribs near cassette and anterior opposite ribs. Post Nasal Space (PNS) lateral neck cassette level of pinna. Valsalva manoevre used. Thoracic inlet for goitre also done. Trachea and larynx with “E” phonation. Lordotic view done for interlober effusion or collapse of right middle lobe. PA – Pt faces cassette and leans backwards 45 degrees. Centre to the middle of the cassette.

Apical view For apices-Tube 30 degrees cephalad, – reverse Lordotic or leans backwards.

Figure 1.6 PA chest. Bronchography An imaging investigation of the bronchial tree. Water soluble contrast medium is used but presently it is not common for it has been replaced by the other medical imaging modalities. The bronchi and their branches in the lungs are visualized to detect any lesions in the airway. Mostly done to check for bronchiectasis which is dilatation of the bronchi and masses of the lungs. It is done under aseptic procedure and local anaesthetics. A sterile trolley is necessary. It is quite an invasive procedure.

Figure 1.7 Bronchography images.

 Acute Abdomen Severe sudden abdominal pain or colic which calls for immediate attention. The indications are: Renal calculi, Biliary calculi, Trauma, Bleeding DU, Peritonitis, Food poi- soning, Chest infection, Typhoid, Intestinal obstruction, Ruptured viscera, Tension pneumonia and internal bleeding. The basic views are AP abdomen supine, AP erect and chest. Supple- mentary – Dorsal decubitus and Lateral decubitus using horizontal beam to show fluid levels.

AP supine Patient lies supine, spine straight and pelvis symmetrical. Centre to the midline at the level of lower costal margin. Exposure is made on arrested expiration to avoid motional blur – Shows distension and gas distribution. AP erect as for AP supine but patient is standing. This shows fluid levels. FFD 100 cm and cassette 43×35 cm. Dorsal decubitus Pt lies supine; one arm over the head and the other supports the cassette by the side. FFD 100 cm, cassette size 30×40 cm, beam horizontal and exposure on arrested expiration. Centre to middle of cassette. For fluid levels when erect impossible. Lateral decubitus AP or PA as for supine but horizontal beam used – for fluid levels. Kidney, Ureters and Bladder-KUB. This will show the abdomen and more so the urinary system for stones or pathology. AP supine done making sure the upper poles of kidneys are shown and no folding of clothes or skin. FFD 100 cm, cassette 43×35 cm and exposure on arrested expiration.

Figure 1.8 AP abdomen.

Chapter 2 Medical Imaging Techniques and Procedures of Skull, Teeth, FBs and High Kilovoltage Technique

 Objectives • Describe the imaging technique for cranial and facial bones • Explain the WHO dental formula • Discuss the imaging technique for the teeth • Explain pediatric imaging • State High kilovoltage and soft tissue imaging • Discuss foreign body imaging.

 Skull Imaging Skull has 14 facial and 8 cranial bones. Cranial bones make the cranium with the vault and base. Facial bones make the face. Skull is very difficult to image because of the shape and bone position. The land marks include:

Radiographic base line (RBL) A line from E.A.M to the outer canthus of the eye. Anthropological line From EAM to the infra orbital line. Median sagittal plane through middle of the head and body (AP).

Coronal Anterior to posterior plane

Interpupilary line Between eyes (pupils).

Equipment General X-ray machine, H.T generator, Cassettes of various sizes and positioning pads.

Patient preparation Remove all radio-opacities and reassure the patient.

Indications Brain pathology, Trauma leading to fractures, dislocations and displacement of bones. Grids are used when necessary for the thick body parts.

 Cranium Basic views • Postero-anterior or Occipito-frontal • Townes view – 30 degrees fronto-occipital • Lateral view.

Supplementary views • SMV – Submento – Vertical view for skull base. • SMV under tilted for jugular foramina. • Coned lateral view for pituitary fossa with horizontal beam as for lateral skull. • Tangential view for lesions. Occipito-frontal Patient lies prone on the X-ray couch, hands clasped under the chest, the body straight, median sagittal plane and RBL perpendicular to the film. Interpupilary line parallel to film. Centre in the midline 5 cm below RBL, FFD 100 cm, cassette 24×30 cm. This view shows petrous portion of temporal bones within the orbits. To throw the bones from orbits angle the tube 20 degrees caudad and 5–10 degrees petrous in infraorbital line centering at the glabella.

Fronto-occipital This can be done when the injury is posterior, for children and severe injuries. AP patient lies supine, RBL and median sagittal plane perpendicular to the film, 24×30 cm cassette used, FFD 100 cm. Centre 2.5 cm above the Glabella.

Townes view 30 degrees Fronto-occipital. Positioning same as fronto-occipital with tube angled 30 degrees caudad.

Lateral air, aero- coele in frontal bone and free air Patient lies prone, head in the sphenoid bone. rotated with injured side in contact with couch, interpupilary line perpendicular to film and median sagittal plane parallel to film. The arm of injured side along the trunk and the other arm folded hand in front of face. FFD 100 cm, cassette 24×30 cm and grid used. Centre between glabella and EAM or 2.5 cm above EAM. In all cases of trauma, horizontal beam used to show ventricular Figure 2.1 Lateral skull projection of a child. Base of skull Sub mento-vertical view (SMV) Patient seated or supine is maneuvered such that the RBL is parallel to the film and angles of the mandible equidistant from the film with neck extended. FFD 100 cm, cassette 24×30 cm. Centre between angles of the mandible with tube angled 5 degrees cephalad-to face. Pillows used.

Pituitary fossa Coned lateral view done with horizontal beam. Centre 2.5 cm above and in front of EAM. PA and Townes are also recommended when necessary. 24×18 cm cassette, FFD 100 cm and grid applied.

Jugular foramina Lie along petro-occipital suture and transmit internal jugular veins, accessory and glossopharyngeal nerves. SMV is done with tube angulation of 20 degrees caudad. Shown between transverse processes of atlas. FFD 100 cm, 24×18 cm cassette and grid used. For localized lesions and depressed fractures, tangential views done. Centre to the lesion in profile (aligned).

Facial bones Fourteen facial bones and very difficult to image because of the bone arrangement. Indications and requirements basically the same as those of cranial bones. The basic views are: Occipito-Mental, 30 degrees Occipito – Mental and Lateral. Supplementary views are Fronto-Occipital for zygoma, Lateral coned for nasal bones or Occipito-Mental and Supero-Inferior. Orbits – 20 degrees Occipito – Frontal, Occipito-Mental and lateral. Optic foramina – Obliques 35/35 degrees both sides.

Occipito-mental (OM) Referred to as Walters view. Patient is seated or lying prone on the couch with hands under the chest. Median sagittal plane perpendicular to the film, orbito-meatal line 45 degrees to the film, FFD 100 cm, grid, 24×30 cm cassette, chin on couch. Centre to the nasion with central ray passing through superior orbital margin. 30 degrees Occipito-Mental (OM). As for OM but centre to the midline at the level of lower orbital margins with the tube angled 30 degrees caudad. Shows more of zygoma and maxillae and if over tilted can show Odontoid peg of the Axis which is the second servical vertebra. Severe injuries supine done as Mento-Occipital with 45 degrees tube angulation and horizontal beam seated or erect for fluid in maxillary antrium.

Lateral As for cranium with patient prone, interpupilary line perpendicular to film and median sagittal parallel, arm near injured side along trunk and the other in front of face, 24×30 cm cassette, FFD 100 cm centre to the zygoma. For black eye erect or supine done to show orbital empysema which is associated with air in the ethmoidal sinus. These cthree projections for facial bones are also used for para nasal sinuses in times of sinusitis and in sitting position to show fluid levels.

Mandible This is the only movable bone of the skull. In PA obscured by the cervical and lateral superimposed. Fractures common and dislocations. Orthopantomog- raphy (OPG) can be done to show the whole of the bone. Basic views are PA and lateral oblique.

PA The patient lies prone, chin tucked in RBL and median sagittal plane perpendicular to the film, hands under the chest. FFD 100 cm, film 18×24 cm and centre in the midline at the level of angle of mandible. Figure 2.2 Mandible PA with fracture right body. Lateral oblique Patient half prone with shoulder remote from injured side supported on pillows or foam pads and hand in front of face. FFD 100 cm, cassette 18×24 cm, RBL and sagittal plane parallel to film. Centre 5 cm below the angle of the mandible remote from the film with the tube angled 20 degrees cephalad to separate the two sides of the mandible.

Temporo – mandibular joint (TMJ) A sliding synovial joint demonstrated by 35 degrees Fronto-occipital and lateral obliques 25 degrees both sides. TMJ – Both sides as in mandible and in closed and open mouth to see the extend of movements of the joints.

Para nasal sinuses (PNS) Frontal, Maxillary, Sphenoidal, Ethemoidal and mastoid air cells. OM, OF 15 degrees caudad and patient steady. Lateral with beam collimation done. FFD 100 cm, Grid and cassette 24×18 cm.

 Dental Imaging Adult human being has 32 teeth. Two types of teeth-temporary or deciduous and permanent. These are Incisors, Canines, Premolars and Molars. A child has 20 teeth referred as milky teeth. Erupt at 6 months to 2 years. The child has 4 incisors, 2 canines and 4 molars in each jaw. The teeth are attached to the socket by cement and periodontal. Adult 4, 2, 4 and 6 each jaw. Have crown, neck and root.

WHO dental formulae In adult 18 17 16 15 14 13 12 11//21 22 23 24 25 26 27 28 – Upper jaw right to left each two digits a tooth by name. 48 47 46 45 44 43 42 41//31 32 33 34 35 36 37 38 – Lower jaw right to left each two digits a tooth by name.

Child formula 55 54 53 52 51//61 62 63 64 65 – Upper jaw right to left each two digits a tooth by name. 85 84 83 82 81//71 72 73 74 75 – Lower jaw right to left each two digits a tooth by name. Mesial are the arches anterior towards incisors, distal posterior towards molars, labial or buccal cheek side of the jaw and lingual or palatal inner jaw side.

Types of dentistry imaging Two types thus Intra oral and extra oral. Films occlusal denoting upper and lower jaws. Panoramic tube operates from inside the mouth.

Orthopantomography (OPG) Specialized equipment to show both dental arches and good for fractures and rami of the mandible.

Land marks a) Upper positioning line Extends from tragus of the ear to the ala of the nose – 3–7.5 cm above upper occlusal plane. b) Lower positioning line Line from tragus of the ear to the angle of the mouth. 2 cm above lower occlusal plane with open mouth.

Equipment Include a special dental machine, dental chair, hangers, films 1.1/4×1.5/8 adults and children smaller 1×1.1/4 inches. Occlusal larger with lead foil to absorb scatter. Film Identification is quite difficult. The hanger should show upper and lower teeth locations which represent the various teeth. Emboss- ment should face the operator and biting surfaces. Flip to check tightness so that they do not fall. Clip should not coincide with the embossment and inscribe name on a tabloid or tang on the hanger.

Patient preparation and indications Win patient confidence, identify with form, remove dentures and FBS from face. Infections like dental caries, un erupted teeth, embedded teeth, eden- tulous patients and retained roots. Patient is usually in sitting or lying on a dental chair or stool. Always the occlusal planes are horizontal and median sagittal plane vertical. This is achieved by moving the head and tucking the chin in. Patient should relax and made comfortable. Head moved and foam pads used for supporting the patient. For canines and incisors, the film is placed vertically and premolars and molars it is placed transversely in the mouth. Tube is directed at right angle to the film. This may not be possible due to the curves but a compromise is reached. Scissors, finger or any other improvisation is used to support the film and the patient must be at rest. The average tube angulations are as follows:

Upper jaw Incisors + 55 degrees, Canines and Premolars + 45, Molars + 35 and Occlusal + 85.

Lower jaw Incisors – 20, Canines and Premolars – 10, Molars – 50, Occlusal – 90.

Centring points Upper jaw Incisors – Tip of the nose, Canines – Ala of the nose, Premolars – just below midpoint of the orbit and Molars – outer canthus of the eye.

Lower jaw Incisors – Symphysis menti, Premolars – In line with midpoint of orbit on the body and Molars – In line with outer canthus of the eye on the body.

Occlusal views Taken using occlusal films to demonstrate cysts, alveolar pathology and get plan view of the mouth. The occlusal film is placed between the teeth and for upper incisors; the tube is directed at Nose Bridge at 65 degrees. Plan view tube at vertex at 90 degrees to the film. Lower incisors SMV tube at 40 degrees and plan view centre to menti.

Bite wing views These demonstrate upper and lower crowns for dental caries. Film is placed horizontally and one bites on a bite block. Tube is centred at the occlusal plane at right angles to the film. Edentulus patients i.e. patients with no teeth, increase angulation for root and gum, decrease exposure gum less dense and include the whole root.

Orthopantomography (OPG) Technique used to obtain the whole of the dental arches tomograms using a special machine called OPG – Orthopantomogram. This is used for: Check jaws at first orthodontic visit, mandibular fractures, TMJs, show changes in gross pathology of maxilla, nose and ear. The machine has X-ray tube, slit diaphragm linked to a curved cassette, film holder and control desk. The tube and film move in opposite direction, patient is stationary. Due to the curves, the change of direction is twice to remain at right angles with the arches. The slit beam transverses the whole arches making exposure. In patient positioning, the head is adjusted and held in a Cranio-Stat. Upper and lower arches are at focus.

Radiation protection High dose imaging procedure because of the low exposures and difficult due to: a) Only low Kv is used in most dental units 55–60 kv b) Short FFD used c) No additional filtration d) Multiple exposures needed e) No lead lined cones f) General equipment can be used but hard to move. Pt should wear a lead rubber gown, beam away from body, hold film by finger not staff or radiographer and use meticulous technique.

Exposure factors Dental unit: FFD 23 cm, Time 0.25–1 second, MA 10 and Kv 45–60. General unit: FFD 50–62 cm, MA 50, Time 0.25–1 second and Kv 75. Fine focus is used for details. Films are processed in a special dental processing unit. Make sure films are not mixed even with the general ones. Good temperature 68 degrees, 4 minutes, proper mixing of chemicals and washing.  High Kilovoltage (KV) Imaging Objectives • Explain high Kv imaging • Name high Kv applications • Explain the advantages of this technique • State the disadvantages of high Kv imaging. In imaging, high Kv means carrying out examinations using high range kilovoltage – range 100–150 kv. At 50 kv low energy high contrast – photon electric absorption (attenuation) i.e. 50% Compton scatter. At 100 kv high penetration, less scatter and absorption hence leveled densities. Scatter is reduced by use of cones, grids, light beam diaphragm (LBD) and compression of the region-less volume – less kv high skin dose high kv equal densities. High kilovoltage is not common now because of the many modalities in use and automated programmed machines with no exposure selection manually.

Advantages 1. A wide range of tissue density can be visualized in a single film 2. Reduced MAS – reduced chance of motional blur on the film 3. High anode heating reduced – less time 4. Greater range of exposure latitude 5. Low MAS fine focus fine details 6. Radiation dose to patient reduced.

Disadvantages 1. Special equipment with high Kv needed 2. Loss of details and poor contrast in the soft tissues 3. High grid ratio due to scatter 4. Gonad dose high in chest imaging 5. Risk of over penetration unless using APR (Automatic Programmed Radiography) 6. Poor detail in skeletal work and poor contrast in tomography.

Applications 1. Hysterosalphigogaphy (HSG) – reduced gonadal dose 2. Barium examinations – rapid serials hence less heating 3. Pelvis – iliac regions 4. Cervical and thoracic spine 5. Lateral views of lumbo-sacral region.

Foreign bodies-FBs These are strange objects or materials in the body which are not supposed to be in the body. They are introduced through natural orifices or penetrating wound. The aim is to:

1. Establish presence and identity of the FB 2. Show the position in relation to other body structures 3. Locate position if required 4. Assess secondary or associated damage to the body. Ensure no artifacts to confuse with FB, clean cassettes, bucky and remove clothes. Two views at right angles and no movement. Follow up to be sure and do tangential views to establish whether tissue embedded. Cover large area not to miss and localize before incision or removal.

Types of FBs Four types for both adults and children thus: 1. Ingested through mouth by swallowing e.g. fish bones, meat bones, dentures, teeth, coins, pins, screws and toys and can be in the pharynx, oesophagus downward. 2. In haled FBs – go to the lungs and can cause lung collapse – dentures, corns, peanuts, beans and clips. 3. Inserted FBs – to the orifices thus mouth, urethra, rectum, EAM and vagina. 4. Embedded FBs – lodged in the tissues – glass, lead shots, bullet shrap- nels (bullet pellets), arrows, scissors and knives – immediate attention. Equipment depends on the type and patient preparation is assurance, procedure, cloth removal and ask for how long FB in situ.

Imaging procedure 1. Ingested FBs for children AP alimentary tract cover lower neck and symphysis pubis. Short exposure factors, cassette 43×30 cm. Adult films in order – lateral neck, chest posterior oblique and AP abdomen. Position- ing as in conventional imaging. 2. Inhaled FBs – PA chest as for routine imaging. Lateral or oblique may be done. 3. Inserted FBs: Nose-Routine Occipito-Mental and a lateral. Ear–basic views of the skull and tangential views may be necessary. Contrast may be used to coat the FB if radiolucent. Urethra, vagina and rectum – AP pelvis and endoscopy may be done. 4. Embedded FBs – Can be in the limbs, abdomen, skull and chest – AP done. 5. Eye FBs – Intra – Ocular – OM and lateral – Another may be taken, 2 exposures looking straight up and down.

 Sinuses and Fistulae Sinus Its a cavity within the tissues. This can involve muscles and bones. It leads from surface to inside or vice versa from abscess or drainage tube. Sinogra- phy may be done using contrast. This will show source, extend and ramifica- tions or channels. Patient reassured and dressed. Pressure is applied on the sinus if bleeding occurs.

Fistula Abnormal passage connecting a cavity to another or surface to body e.g.: Fis- tula in Ano – Ischial rectal from to skin, Biliary fistula – there is bile leakage from gall bladder or ducts after surgery. Blind fistula opens at one end only.

Fistulography Radiographic examination of a fistula using contrast medium. Done using contrast medium. If in colon, water soluble contrast used. Patients with radioactive implants attended in minimal time.

Faecal fistula Follows intestinal operation and there is sepsis.

Vesco-vaginal fistula (VVF) An opening from urinary bladder to vagina. This can be due to surgical error, delivery or ulceration due to carcinoma. Recto-vaginal fistula Due to peritoneal tear or in delivery. Faecal matter in vagina.

Macroradiography Can also be done which involves magnified images of the body part in question.

 Pediatric Imaging This is very difficult because of the nature of the patients. It needs a lot of cau- tion and patience to avoid repeats which add more ionizing radiation to the patient. Projections may change hence one will be doing alternative views e.g. AP of chest. Proper identification of patients and films is very important. Use meticulous technique to eliminate repeats which will add more ionizing radiation to the child hence more danger of radiation hazards.

Chapter 3 Medical Imaging Techniques and Procedures Using Contrast Media and Mobile Examinations or Portable

1. This will include contrast media examinations of body systems. 2. Mobile and Portable examinations. These are – Ward Imaging, Operating theatre Imaging, Home based Imaging and Forensic Imaging. 3. Most of the contrast examinations have been replaced by the modern technology thus CT, MRI and Ultrasound.

 Contrast Examinations These will include: Alimentary tract, Biliary tract, Urinary system, Reproduc- tive system, Central nervous system, Circulatory system and Interventional radiology. The sequence is as follows:

1. Definition of the examination 2. Patient preparation 3. Contrast medium used and dosage 4. Indications and contra-indications 5. Role of the radiographer 6. Equipment and projections or technique.  Alimentary Tract Examinations Barium studies Organs of the gastro intestinal tract (GIT) These organs are the mouth, pharynx, oesophagus, stomach, small intestines and large intestines or colon. Accessory organs are pancreas, biliary tract or tree, salivary glands, liver, tongue and teeth.

Examinations of GIT The following examinations are carried out in the investigation of GIT thus: Barium swallow, Barium meal, Barium follow through and Barium enema.

Contrast media Barium sulphate in form of suspension or paste. This opacifies the organ in question such that the soft tissues can be seen. Gastrografin with iodine where barium sulphate is contra-indicated e.g. in partial or complete stenosis, bleeding DU, acute illness or fistula. Air in double contrast barium enema.

Equipment X-ray set with fluoroscopic facilities. Preferably with image intensifier and television monitor, Tilting couch with floating table top, Foot rest, Adequate output preferably 300 MA, under couch and over couch X-ray tubes.

Accessories Loaded cassettes (all sizes), 43×35 cm, 40×30 cm, 24×30 cm, 18×24 cm, barium cups, feeding cups and mixers, Pillow, lead rubber aprons, gloves, clean no-opaque gowns, swabs for wiping mouth (vomitus), bowl and recep- tacle for solid materials.

Responsibilities and duties of radiographer Before examination 1. Clean or tidy the equipment. 2. Switch on the equipment and make sure it is in good working condition. 3. Place the table in the required position, ascertain required lighting as necessary. 4. Have adequate clean cassettes of appropriate sizes. 5. Place the cassettes appropriately; they should not be mixed up-the exposed and unexposed. 6. Select the required type speed, fast or slow screen cassettes or films. 7. Check for tight closure of cassettes to avoid film fogging and 8. Prepare the barium sulphate suspension.

Care to patient 1. Receive and identify the patient 2. Change the patient and explain the procedure 3. Check for instructions if followed 4. Escort patient to examination room.

During examination a) Administer barium sulphate to the patient b) Help radiologist communicate with the pt c) observe the pt and report any incident d) Ascertain pt’s comfort e) Change the films after exposure f) Adjust exposure factors (new equipment does not need this) g) Protection from radiation to all people in the room.

After examination a) Help the patient from the couch b) Have the pt clean the mouth c) Ask patient to change back into his clothes d) Escort the pt to waiting area e) Inform of any follow-up films f) Clean the room and prepare for next examination g) Process the exposed films h) Remind pt of next appointment and discharge pt if fit, from the department and i) Inform of any change of colour of faeces.

Barium swallow This is a radiological examination of the pharynx and the oesophagus by use of contrast medium. Contrast medium used is barium sulphate in paste form and is best done under screen control. Radiographers can also do it without screening.

Indications for barium swallow Foreign body, carcinoma, oesophageal varices, strictures, stenosis and fistulae. Investigation of heart diseases and gastroesophageal reflux disease (GERD).

Patient preparation a) Patient is given a written appointment indicating clearly date, day and time of examination, not to eat or smoke after midnight before the exam. b) Wear a hospital gown and remove all jewellery including body jewellery such as nipple and belly-button rings, dentures, hair clips, or other objects that might show up on an X-ray film. c) Patient is put on the couch mostly in vertical position, given thick paste of barium sulphate which serves as a bolus. d) Position the patient behind the image intensifier and instruct the patient to swallow. e) Then follow the bolus image on the screen and take the films periodically as required. f) Posterior-anterior and lateral views taken of the chest are done with obliques. Exposure on arrested expiration and beam collimated. In absence of screening facilities, blind radiography is employed.

Barium meal This is an examination of the stomach and duodenum with the aid of barium sulphate suspension as the contrast medium. The lower portion of oesophagus is also examined.

Indications Peptic Ulcers (PU), neoplasm, pyloric stenosis, foreign bodies and hiatus hernia.

Technique 1. Patient is initially in erect position. 2. Patient is put in the right anterior oblique position. 3. Small glass of barium is given to the patient to drink. This is observed closely on the screen as it passes down the oesophagus to the stomach. 4. The patient rolls on the table twice for even coating of the stomach walls. Take posterio-anterior and right anterior oblique views. 5. Patient is given more barium suspension to drink if necessary. Right and left anterior oblique views are taken to show posterior and anterior aspect of lesser curvature. 6. Patient placed in supine position to demonstrate the fundus of the stomach. 7. Patient is examined in Trendelenberg position to demonstrate any hiatus hernia. 8. Serial of films are taken to demonstrate the duodenum. Split films are taken to demonstrate part of the duodenum (caps) which may be taken at short interval speed. Any technique employed should produce radiographs with all the phases of movement of the cap. When there is a delay at the pylorus of the stomach, the duodenal cap does not fill immediately; the patient is made to lie prone with the left side raised and a pillow placed beneath the ribs of the left side.

Barium follow through Radiological examination of the whole small bowel from duodenum, jejunum to ileo-caecal valve following introduction of contrast medium. Combination of fluoroscopy and overcouch is usually employed. This is performed when a lesion at the distal end of the ileum, appendix, caecum or the proximal part of the ascending colon is suspected. After giving barium meal fluoroscopic examination of stomach and duodenum is performed. Then films are taken after 2, 3 and 4 hrs. This is helpful in diagnosis of the appendicitis, ileo-caecal tuberculo- sis, Crohn’s disease and carcinoma of caecum. Patient preparation as for barium meal.

Technique 1. After contrast introduction, patient lies prone or on the right side until barium has left the stomach. 2. Over couch radiographs taken in prone till contrast reaches the terminal ileum at 15 mins interval, then half-hourly. 3. Once stomach is empty, pt can take food to accelerate transit of barium through the small bowel. High kv (120 kv) with short exposure time used.

Prone view a) Pt lies in the mid-line of the x-ray table. 35×35 cm cassette used, centre to the mid-line of cassette. b) When stomach is full, lower boarder of cassette placed at the level of posterior iliac spine. c) When empty, lower boarder is placed at the lower margin of symphysis pubis.

Erect view Shows fluid levels in presence of jejunal diverticulosis.

a) Lower border of 35×35 cm placed at the level of symphysis pubis. b) Centre to the midline at the level of lower costal margin. Use high KV technique.

Barium enema This is a radiological examination of the colon by retrograde infusion of contrast medium. Double contrast used because it involves radio paque and radio luscent contrast media, (air and barium sulphate). Consider possibility of pregnancy in women of reproductive age.

Indications Bowel polyps, Ulcerative colitis, Acute appendicitis, Twisted bowel loops, Cancer, Colitis, persistent diarrhoea, megacolon, Intussusception, Hirschsprungs disease, Congenital abnormality and Diverticuli.

Patient preparation • Low residue diet 4 days prior to exam. • Empty the colon before examination, either by use of aperients 2–3 days or colonic washout before examination. • Nil by mouth 4–6 hours before examination. • Pt undresses completely and wears an open – back gown. • No pre-medication required. In some cases, buscopan is given to relax the smooth muscle and reduce bowel peristalsis. • Patient to take 2 tablets of dulcolax at least 2 days prior to examination. • Light meals a day before exam. • Patient to place dulcolax suppository in the rectum half an hour before exam.

Contrast medium Barium sulphate about 500-600 mls introduced rectally. More required in case of megacolon. Luke warm water for burium suspension.

Trolley set up • Enema container with suitable tubing length. • Enema drip which is adjustable in height … 100 cm. • Polythene connection between tubing and catheter. • Catheters, disposable enema set preferred. • Barium sulphate suspension at correct temp. 38 degrees. • Gause swabs, lubricating jelly, Dressing towels, bowl receivers, Bed- pan readily available and cover and shringes.

Equipment As for barium meal.

Technique 1. Explain exactly what will be done to the patient. 2. Position the patient on his side with knees flexed. 3. Lubricated catheter inserted approximately 10 cm into the rectum and secured in place by tape. 4. Balloon is then inflated by means of disposable syringe. Height of enema bag about 100 cm above the table. 5. With patient prone, the table is tilted 10 degrees head downwards. 6. Little barium is run through the tube to confirm no blockage. 7. Patient asked to turn over on his back. 8. Barium is run slowly until it reaches the splenic flexure. 9. Air is gently pumped forcing the column of barium along the colon creating double contrast. 10. When the filling is right, undercouch films are taken. These are PA oblique and Lateral. • Over couch films include AP. Patient rotated on the left side and then into the right anterior oblique to coat the internal mucosa. • Under couch views are taken with the patient in lateral, oblique and erect positions.

Antero-posterior Patient lies; supine lower border of cassette is placed at the level of the symphysis pubis. Centre in the midline at the level of lower costal margin.

Figure 3.1 Postero anterior (PA) Enema projection.

Left lateral decubitus • Patient lies on the left with his arms on the pillow above the head. • Grid cassette supported vertically or posterior to the patient. • Horizontal beam used and centre at mid-line at the level of lower costal margin. • Right lateral decubitus patient lies on the right side and procedure as for left lateral decubitus.

Post evacuation projection AP abdomen done when immediate examination is complete and after evacuation positioning as for AP abdomen.

Ileostomy and colostomy patients Examination of the colon distal to the site of colostomy is usually performed by infusing barium via the rectum until it reaches the site of colostomy. Con- trast medium e.g. urografin 150 or hypaque 25% may be used instead of barium. This is to avoid barium leaking from the anastomosis site and pool- ing outside the lumen of the bowel.

Intussusception This is a condition in which one part of the alimentary tract becomes pushed or invaginated into another part below. Common with the terminal ileum being pushed into the first part of the colon. Mostly common in infants between 4 months and 2 yrs. If diagnosis is uncertain, barium enema may be used to confirm producing a typical cup-like appearance at the head of the enema (where it is entering).

Hirschsprungs disease Condition in which the rectum is normal, narrowed section of the sigmoid colon and grossly enlarged colon above this. Occurs due to congenital anom- alies and is idiopathic (unknown origin). Ba-enema may be used to confirm this condition. Colonic washout used and enama wash-out enema recommended after exam.

Patient after care • Patient leaves the department when fine. • Warn the patient of colour change in the faecal matter. • Take plenty of water to minimize faecal impaction. Complications of barium enema Barium impaction is a blockage of the colon caused by the barium. This is a rare event. Dehydration due to taking enemas and laxatives before the procedure. Puncture of the colon. Small risk of cancer due to radiation exposure.

Double contrast • Double contrast technique is done after infusion of barium sulphate has been completed and colon has been partially evacuated. • Colon is distended with air. • Small defects that may have been previously obscured by barium may become visible with double contrast. Also demonstrates polyps. • Air is pumped in gently by means of a syringe. • Rotate the patient to manoeuvre the air round the colon. • Under-couch radiographs are taken using KV 10 less than for filled colon. • At the end of exam, remove the catheter and direct the patient to lavatory to get rid of air. Figure 3.2 Barium enema showing CA colon Small bowel enema • This is an examination of the small bowel. • Contrast injected via a catheter to the area of interest. • In barium enema, catheter is put through the rectum. Catheter to stomach and duodenal area then followed to the end.

Diabetic pts for colon examination Diabetic pts present special problems as it is essential to starve before examination. Diabetic pts rely on properly controlled diet. Patients who receive insulin are asked to omit the morning dose and carry them with their normal breakfast to the dept; alternatively a meal can be arranged with the hospital. Given 1st priority in the hospital and department.

Biliary examinations Oral cholecystography, Intravenous choledochography, Endoscopic retrograde choledocho-pancreatography (ERCP), percutaneous transhepatic choledochography and Operative choledochography. Post operative T-tube choledochography radiographic examination of the biliary tracts is usually required to assess the function and demonstrate anatomical abnormalities. Contrast medium is therefore needed to demonstrate the biliary tract. Contrast medium may be given orally, intravenously or by retrograde cannu- lation of the ampulla of vater, percutaneously into the hepatic ducts, direct injection at operation and through a drainage tube after operation. Biliary tract may also be examined by CT and ultrasound. Oral contrast medium is excreted by the liver and enters the gall-bladder where it is concentrated.

Oral cholecystography An iodine-based oral contrast medium is ingested the evening before the examination. Films of the right upper quadrant the following day demonstrate an opacified gallbladder. It does not opacify if there is cystic duct obstruction or the patient is jaundiced. Calculi are seen as filling defects. A film after a fatty meal shows the extent of gall-bladder contraction. Figure 3.3 Ap abdomen showing full gall bladder.

Operative cholangiogram This investigation is performed at cholecystectomy when the cystic duct is cannulated and contrast injected to outline the common bile duct.

T-tube chlangiogram This examination may be carried out approximately 10 days after surgery to identify any remaining calculi in the common bile duct. Contrast is injected into the T-tube under fluoroscopic control to exclude residual calculi. Figure 3.4 A normal T-Tube cholangiogram. Transhepatic cholangiogram A fine needle is inserted directly into a bile duct in the liver under local anaesthetic. Contrast is injected to visualize the entire biliary system and thus try and elucidate a cause for obstructive jaundice.

Endoscopic retrograde choledocho-pancreatography (ERCP) After the patient is sedated and the pharynx anaesthetized, an endoscope is introduced and advanced through the mouth into the duodenum. Contrast injection is directed into the ampulla of Vater, to demonstrate both the bile ducts and the pancreatic duct. Common bile duct stones can be removed through the endoscope by insertion of a catheter with a balloon. Malignant common bile duct strictures can also be stented.

Figure 3.5 ERCP Examination.

Ultrasound is the initial investigation of choice in a patient with jaundice. This may demonstrate a dilated common bile duct down to the level of the stricture. ERCP will show abnormalities of the upper gastrointestinal tract and the pancreas, in addition to the common bile duct stricture. Transhe- patic cholangiography may be required if ERCP is unsuccessful. Percuteneous transhepatic choledochography (PTHC) This is the radiographic examination of the biliary tree following direct injection of contrast medium into the liver tissue. Indications Jaundice, thought to be of obstructive origin, differential diagnosis between intrahepatic and extrahepatic obstruction (Cholecystitis), demonstration of dilated intrahepatic ducts (dilated intrahepatic ducts are usually confirmed by ultrasound before this examination is done).

Technique 1. The bile ducts are dilated; bile is aspirated before contrast medium injection and send for microbiological examination. 2. If a bile duct has not been entered during the first withdrawal, this may be attempted up to 10 times. 3. After which the examination is abandoned with assumption that bile ducts are not dilated. 4. If the examination reveals obstruction or dilated intra hepatic ducts, the patient goes to theatre for laparatomy. Postero-Anterior (P.A), 45 degrees Right Posterior Oblique, Right Lateral, Trendelenburg Position (Supine Postero-Anterior P.A).

Figure 3.6 Ultrasound image showing GB calculus.  Urinary System Excretion system of the body consisting of two kidneys, two ureters, urinary bladder and urethra. Examinations of this system are plain abdomen, Intravenous urography (IVU), retrograde pylography, cystography, cysto- urethrography, renal puncture and renal arteriography.

Patient preparation • Abdominal preparation for removal of gas and faecal matter as for barium meal • Laxatives can be given for two days before examination or a day depend- ing on the departmental routine. • A series of films are taken for intravenous urography. One AP abdomen as a control or scout to check preparation, positioning, exposures and reveal any renal culculi. This examination (IVU) demonstrates the whole urinary system thus kidneys, ureters and urinary bladder. • After injection of contrast medium conray 280 or urografin 60% 20–40 mls films are taken thus nephrogram immediately, 5 minutes, 15 and 25 mins full length. The rest are focused on the renal area. • Post micturation film is taken of the pelvic region to show bladder empt- ing capacity. This examination is being replaced by other modalities like CT and ultrasound although in ultrasound there is limitation when one is looking for the physiology of the kidneys.

Indications for IVU Renal failure, hydronephrosis, renal mass, hypertension, ectopic kidneys, pyelonephritis, ruptured kidneys, renal calculi and renal TB.

Equipment and accessories • General X-ray unit with adequate output, • Potter bucky • Films • protective devices • Gowns and compression bands. • After AP abdomen, supplementary films may be taken thus erect AP abdomen for gall calculi differentiation, prone also calculi movement and obligues. • Delayed films can be taken for delayed excretion. A surgical trolley will be prepared with the following: Upper shelf 20 or 50 ml syringes, 2 ml syringe, IV needles, kidney dish, drawing up cannula, dressing bawl, a pair of dissecting forceps, towels and swabs. Lower shelf will hold ampoules of contrast medium in warm water, file, sphygmomanometer or tourniquet, skin cleanser, vomit bowel, sand bag, oxygen cylinder and resuscitation drugs.

Figure 3.7 IVU image.

Retrograde pyelography or ascending pyelography Not an examination of choice and not common presently. It demonstrates the pelvicalyceal area and the ureters. Catheters inserted in theatre. Equip- ment and technique as for IVU. Other modalities have replaced this examination. Cystography and urethography involve passage of a catheter through the urethra to fill the bladder with contrast medium then films taken of the bladder and urethra. Urethra as one is passing urine to outline the urethra with contrast medium. Renal puncture or taking of biopsy is currently done with aid of ultrasound, CT or II.  Reproductive System Male and female reproduction system for life continuity in terms of future generation. The female has internal and external organs. The examinations are grouped into two parts:

1. Obstetrics for gravid uterus and 2. Gynaecological for non gravid uterus. Gynaecological examinations are two: a) Plain pelvic examination to show uterine lesions or masses and b) Contrast media examinations. The most common contrast medium examination is hystero salpin- gography (HSG) to show cause of infertility. Ultrasound has taken over the female examinations to avoid irradiating the foetus and the mother. HSG is being carried out at the moment. Hysterosalpingography demonstrates the uterine cavity and uterine tubes to determine patency of the tubes. • This examination may be done using general equipment or by fluoroscopy or screening. Equipment for general work and screening equipment needed. • A trolley with upper sterile part and lower unsterile is needed. Contrast medium can be conray or urografin 60% or non ionic contrast medium in the market. • Patient preparation is needed to avoid gas and appointment given a day or so. • Privacy paramount for it is a very embarrassing examination. A series of projections of pelvis done AP during and after the injection of the 20 mls contrast medium. Patient is reassured and when stable discharged. • Trolley items will include: Upper shelf vulsellum forceps, vaginal spec- ulum, uterine sound, uterine cannula, sponge holding forceps, tissue forceps, 10–20 mls syringe, lotion bowl, gallipots, towels, gauze swabs and gloves, gowns and masks. Lower shelf – cleansing lotion bradosol or other but not spirit, contrast medium, file, receiver, pad and bandage, emergency try and small mackintosh towel. Figure 3.8 HSG AP pelvis showing peritoneal spill.

 Nervous System This comprises of central and autonomic nervous system. Central has spinal cord and the brain which has cerebellum, cerebrum, mind brain, Pons varolii and medulla oblongata. Inside is the vetricular system of the brain. The examinations are: Plain radiography, Ultrasound-cranials, CT, MRI, Myelography, and Ventriculography, air encephalography, cerebral angiography, discography and radiculography.

Myelography A contrast examination of the spinal cord and nerve roots by use of contrast medium injected through the subarachnoid space. The injection is given via a lumbar puncture at L2 L3 and L4 L5 levels to avoid injuring the spinal cord. This is done to check for blockage of spinal cord by tumours or enchroach- ment into the canal by prolapsed intervertebral discs. An invasive examination now replaced my other imaging modalities especially CT where CT myelography is carried out. A sterile trolley is required for this procedure and equipment with screening facilities and high output generator. Figure 3.9 Myelography images.

 Circulatory System Consists of heart, blood vessels and blood. Examinations are – plain radiography, barium swallow, arteriography, venography, CT, MRI and ultrasound. Digital subtraction angiography obsolete. Indications – CCF, stenosis, aneu- rism, strictures, varices and clots. Sterile trolley used with upper and lower shelves. Angio limited to area of interest e.g. femoral

Sailography Contrast examination of the salivary glands by use of a water soluble contrast medium. Salivary glands are three pairs situated along the mandible with sublingual being under the tongue behind symphysis menti, submandibular below and medial to the body of mandible and parotid the largest from zygoma to the angle of the mandible. After introduction of contrast medium, the technique is lateral and infero- superior, for the first two pairs and AP and lateral oblique for the parotid glands. Contras is injected in aseptic technique. This examination is no longer done. Angiography This examination is for the arteries after injection of contrast medium through direct puncture or catheterization. This done in several way and referred according to the area being investigated. Can include carotid angiography, femoral arteriography, brachial, aortography and four vessel among others. The indications are aneurysms, clots, angiomas and stenosis of the arteries. Venography A contrast examination of the veins using contrast medium. It will depend on the region being examined. It is done under aseptic technique. Indications are clots, strictures, varicoses and space occupying lesions. Ventirculography This is a contrast examination of the ventricular system of the brain done after injection of contrast medium. Brain ventricles are four thus lateral two, 3rd and 4th ventricles. These are examined to check for blockage, masses and stricture.

Interventional radiology This is done as need arises and to specific areas. Some examples include renal cyst drainage, abscess, peritoneal drainage, specimen and many others. Remember patients are booked and starved accordingly in most of the contrast examinations for physiological preparation.

Chapter 4 Medical Imaging Techniques and Procedures – Modern Modalities

This module consists of: Ultrasonography – US, Computerized Tomography – CT, Nuclear Medicine – N/M, Radiotherapy and Magnetic Resonance Imaging – MRI.

 Objectives • Define ultrasound • Explain Ultrasound physics and key terms • State the modes used in ultrasound • State the types of transducers • Explain the applications of ultrasound.

 Ultrasound Sound beyond hearing. This is caused by mechanical vibrations. Ranges from 2 megahertzs to 15 Mhtzs. Hearing range 20 htzs to 20 Khtzs. Hertz is one cycle per second and it is the unit of measurement for ultrasound energy. Ultrasonography is the technique of producing images using a transducer. Transducer is an instrument capable of transforming one form of energy to another. Transducer Produces and receives or detect energy. Mechanical energy converted to electrical. Air and fat reflect back almost all the energy in wave form. Sonic energy used to detect approaching marines. Also bats use this energy – sonus – sound and Graphic – write. Higher frequencies have shorter wavelength and demonstrate superficial structures with good resolution – 7 mhtz, 8–15. Lower frequencies long wavelength and penetrate deep structures and resolution is lower – 3 mhts – 5. Propagation speed depends on the medium. This is faster in solids, tissue and fluid. Artefacts also occur as scanning is taking place and they may be shadowing, rever- beration, mirror and ghost.

 Ultrasound Terms Frequency Number of vibrations per second. Measured in hertz – one cycle.

Amplitude Distance moved by the vibrating molecules from the neutral position. This is loudness in the audible range.

Wavelength Distance between two peaks of the cycles.

Velocity Rate of wave movement, rigidity or compressibility.

Production of ultrasound Sound is produced by thin crystals/ceramic activated by electromagnetic waves of a specific frequency. The crystals are called Piezo electric crystals. Signal/wave is send and received back after a short while. Back wave carry information about the structure and can be displayed on an oscil- loscope as an image. Cathode ray tube displays the images. Medium can be compressed or stretched releasing energy – Transducer has ability to send and receive energy – pressure electricity. Sound waves returned as echoes. Transducers These are the devices capable of producing and receiving sound waves. Con- tain piezo electric crystals. They are of higher and lower frequencies 2.5 mhtz– 15 mhtz. The higher the frequency the shorter the wavelength and demonstrate superficial structures and good resolution and vice versa. Transducer has a plastic housing, acoustic insulator to damp the oscillations, crystal elements, insulating cover, electrodes and a cable for power supply. Transducer surface must be smooth. Aquesonic gel applied for good skin contact, lubrication and air removal. Air is a bad reflector for it will reflect back almost all the waves.

 Display Modes This is what is seen as image but due to the speed; one may not see the form of display like dots. The major display modes are:

1) A-mode – this is amplitude mode. Displayed in form of spikes, linear, straight and one dimension. 2) B-mode or brightness mode displayed as dots and in two dimensions thus horizontal and depth in form of dots. 3) Motion mode – display in form of dots. For moving parts like fluid, blood and heart. Mixture of A and B. Doppler Effect by Andrea Doppler a German mathematician is also motion. Car approaching, moving away.

Types of transducers These can be linear or sector. Linear can be curved or curvilinear. Sector rectangular. Special type for intercostal spaces and cavities – TVS, TRUS and for orbits. Sector has one crystal which swings and are 2 broad types thus mechanical and electrical.

Knobology The radiographer has to understand the machine very well in terms of how it functions. The major knobs/keys are: TGC – Time Gain Compensation – to compensate for the time lost in the deep structures for the echo to come back. Gains – different gain through all structures. Depth – How far a reflector is. Focus – level of organ – capture. Freeze – stop the image from moving on the screen. Markers and print buttons.

 Major Examinations • Abdomen • Obstetrics • Gynaecology • Small parts and • Interventional.

Abdomen Extends from the diaphragm to the lower border of symphysis pubis. The organs are liver, kidneys, pancreas, spleen, peritoneum, uterus, urinary bladder, gall bladder, ovaries, intestines and vessels. Any organ which sends echoes is echoic if not anechoic or echo free. Some cast posterior enhancement or shadowing. Urinary bladder is bright thus enhancement and stones dark thus shadow. Spleen echoes brighter than kidneys. Kidney cortex hypo echoic compared to medulla which is hyper echoic due to the tubules, fat, vessels and calyces. Pancreas on top of three vessels SMA bright, Aorta below SMA and splenic vein. Pregnant mother explore and state foetal well being thus cardiac activity, liquor, head, limbs, spine, placenta and take measurements.

Measurements 1. BPD – Bi parietal Diameter – along the parietal bones. Inner to outer. Masai shield with an arrow. 2. FL – Femoral Length – single bone end to end. 3. AC – Abdominal Circumference – check spine, stomach and umbilical vein. 4. CRL – Crown Rump Length. 5. HC – Head circumference.

Trimesters These are three stages in foetal growth: • 1st trimester 1–12 weeks, • 2nd 13–26 and • 3rd 27–36 or term. All the stages have their own abnormalities – Full bladder. Gynaecologi- cal ultrasound for non gravid uterus to check for masses or other abnormalities. The bladder should be full of urine.

Small parts These are the organs which are superficial and include: Mammary glands, Testes, Thyroid gland, Prostate gland and eyes. Breast has 6 parts: Areola, Axillary, UIQ, LIQ, OUQ and OLQ. Examine seated slowly sagittal, coronal and transverse planes.

Indications Abdomen Reasons for U/S are: Hydatid cyst, splenomegally, portal hypertension, hepatomegally, jaundice, abdominal masses, peritonitis, ascites, gall stones, renal stones, intestinal obstruction, renal failure, hydronephrosis, nephritis, abcesses, FB, ruptured viscera and hernia Moghania and Bodalek. Sliding when fundus up gastro-oesophagus and rolling.

Gynaecological Gynaecological indications are fibroids, masses, haemorrhage, IUCD, bi-cornate uterus, retained products, PID and cystitis.

Obstetric indications These are gestational sac, blighted ovum, implanta- tion, placental site, hyda- tidiform mole, ectopic pregnancy, multiple pregnancy, maturity, abnormality, dermoid cyst, threatened abortion, incomplete abortion, spoting and dating. Figure 4.1 Gravid uterus. Cranials for kids for trauma, coma, biopsy and defects. Made easy by anterior and posterior fontanelles.

Patient preparation • These include 6–8 hours starvation for abdominal organ. • Physical, sociological and physiologically. • Full bladder. • All scanning protocols to be observed as departmental routine and this are done in coronal, sagittal and transverse. • Identify caudad and cephalad.

 Computerized Tomography – CT Objectives • Explain the concept of CT • Explain the key terms used in CT • List the equipment for CT • Describe the scanning procedure • Explain image quality in CT • Explain radiation protection in CT.

Computerized tomography This is a diagnostic modality which uses the principle of tomography to produce body images. A series of images are produced in form of slices while in tomography the layers lie on each other. X-ray machine, detectors and computer used. (Developed by Hounsfield and his team in 1967–1972.) Medical use com- menced in 1972 and thin layers obtained with no overlap to pick tiny lesions.

CT terms Hounsfield (N) The unit of measurement of attenuation. This measurement determines the attenuation of X-rays through the body, water 0, bone + 3500 ad air – 1000.

Voxels Volume elements are small blocks of tissue calculated by a data processor in the gantry. Pixels Picture elements thus final image.

Matrix Number of volume elements per slice. Final image 320×320, 512×512, 1024×1024.

Window level/width Grayness of displayed image and differ in bone, chest soft tissue, head and mediastinum.

CT equipment Gantry Houses tube, detectors, coolers, circuit breakers and interlocks.

Patient couch Offers vertical and horizontal movements and has a cradle to move the patient.

Computer system Collects data and records it in form of images – Operator console, viewing system – Screen, data storage and print • BMD – bone mineral densitometry • PDU – power distribution unit. Figure 4.2 CT machine setup. CT generations 1st generation Was too massive and used long exposure time – 5 minutes, translate rotate configuration, pencil beam and single detector – head only.

2nd generation Translate rotate, fan beam, detector array and short time – 30 secs. Could scan head and body.

3rd generation Rotate, fan beam, shorter time – 1 second and detector array. Could produce ring artefacts.

4th generation Rotate stationary configuration, fan beam, detector array, shorter time 1 sec.

5th generation Rotate mutate scanners with electron beam. Have brushes and multislice 4, 16, 32, 64…

Scanning procedure Consists of three stages thus: Measurement, Reconstruction and Archiving/ display.

Measurement Determines attenuation of X-rays along multiple narrow paths or columns of tissue. Measured in Hounsfields and gantry height determines this measurement. Voxel is the volume and pixel is the picture element while matrix is the final image. Numbers according to attenuation. Water 0, air –1 and bone +1. Image reconstruction. Process of creating images from scan data. This involves: a) Pre-processing of data including re-ordering of the data and is done by programmable array processor – Prospective reconstruction. b) Retrospective construction in which after the re-ordering, the images can further be cut into small slices like from 5 to 2.5 as in joints and in helical and spiral mode. This is done after examination is over. Display/archive This is the displaying of images on the monitor. The images are also stored in discs, files and can also be printed to have hard copies. The hardware for this is in the operator’s console. There are other interesting abilities of the console like field of view.

CT image formation X-ray source is collimated to fan beam which transverses the patient and coupled to radiation detector made of gas-Xenon. A reading is made each time tube moves per degree to 360 degrees and at the end the several read- ings are recorded for computer processing. Small blocks of tissue (Voxels) absorb radiation and this determines the final image (Pixel) and the number of voxels per slice is called matrix and the larger the better the resolution 320×320, 512×512, 1024×1024.

Figure 4.3 CT image showing subdural heamorrhage with midline shift Image quality The final image quality depends on: • The technical excellence of the radiographer. • Machine reliability and efficiency-resolution and sensitivity – ability to differentiate small densities. • Patient co-operation. • Processing of the films. • Radiation protection should be upheld by observing all the necessary measures like ALARA principal and inverse square law.

Advantages • Thin slices with detailed images • Small lesions picked up • eliminates the need for invasive procedures • No superimposition of structures • Very fast/quick • Archiving in several ways • Applied in the whole body.

 Computed Radiography (CR) Principles of computed radiography Computed radiography (CR) can use same equipment as the conventional imaging except there is no film instead is a plate called photo stimulable phosphor (PSP). This is a cassette with screen like material. There is no need of a processing machine either manual or automatic. Laser scanner or reader used – CR reader. The plate carries the latent image which is digitized and can be read after feeding into a computer. The digital image can be viewed and enhanced using software that has functions similar to other digital image processing software as in digital imaging (DR). CR and DR can produce an image in a matter of seconds hence shortens patient stay in the hospital.

Imaging plate CR imaging plate (IP) contains a photostimulable storage layer 0.1–0.3 mm thick and it stores the radiation dose as a latent image within the layer as electron energy. The reader reads this latent image using photomultiplier tube. Imaging plates can be used several times unlike X-ray films and also are reusable.

Advantages of CR • CR can be incorporated into the existing imaging department without a lot of financial implications. • High resolution giving more detailed images. • No need for processing laboratory manual or automatic hence no chemical handling. • Filmless hence no need for intensifying screen and films. • Saves time for it is very fast and not much radiation dose to the patients. • Images can be shared with other institutions for knowledge sharing information. • No extra room as a processing laboratory is not needed. • Repeats avoided with less time in the department, less fatigue to the equipment and the radiographer manning the department.

Disadvantages of CR • Cassette handling that is imaging plate (IP) which is not the case with DR. • Manipulation of image causes geometric unsharpness and low resolution. • Imaging plates are more expensive and can be damaged causing image artifacts and eventually have to be replaced. • Images acquired are subjective because of the ease of manipulation by the radiographer. • Possibility of damaging the PSP.

 Digital Radiography (DR) Digital radiography involves entry of data into the computer as patient identification. The cassette is inserted in the DR reader and image shows on the screen. Image manipulated, marked on the side left or right, density checked and can print or archive in the computer or send to Picture Archiving Com- munication System (PACS).  CR verses DR 1. CR uses a plate while DR uses a detector or flat panel which changes X-ray to electrical energy in form of image which can be manipulated and fed into a screen for viewing and archiving. 2. DR faster and resolution high. 3. DR is expensive than CR. It is important to note that CR uses a laser reader and DR a detector.

Benefits of CR and DR • No wet processing required. • No darkroom hence saves space. • No consumables like chemicals for processing. • No chemical disposal reduces costs and protects the environment. • No film or chemical store, saves space. • No rooms full of films stored. • Reduction of artifacts, improves image quality. • Higher image quality for one is able to manipulate the image. • Share images via email or CD, quicker referral. • Multiple plates of various sizes, flexibility of image capture and saves lots of time. • Reduced repeats which reduces radiation dose to the patient, staff and the radiographer. • Resolution and detail improved hence getting images of good diagnostic value. • No need to repeat images due to loss of films for it is a filmless technique.

Medical applications of CR and DR 1. Mostly used because they have proven reliability. 2. Flexibility to address a variety of clinical use and lower costs. 3. Can convert an existing X-ray room to computed radiography (CR) as what is needed is a laser reader and a photo stimulable plate (PSP) and DR will need a flat panel.

Industrial applications 1. Corrosion surveys on pipes often through installations 2. Examination of valves for erosion 3. Checking for patency in pipes and valves 4. Checking for cracks in pipes and valves 5. Examination of boiler water walls 6. Automotive casting inspection 7. Code work for nuclear installations on all size piping.

Photostimulable phosphor (PSP) Material or photo stimulable phosphor is a material which when exposed to external stimuli or energy like X-radiation emits light or fluorescence and is called a phosphor. It has layers which play different roles just like the film and intensifying screens. These layers are the base, reflective layer, phosphor and overcoat protective layer. Lead backing for scatter absorbing is also present in the PSP.

Image contrast Contrast is the difference between black on a white surface. Densities can be differentiated quite well and this is called good contrast. There is high, low and poor contrast. The clear object will be of good contrast and poor is when the object is not clearly viewed. Exposing a film to produce higher densities increases the radiographic contrast. Contrast in radiography makes the image on an X-ray or other scan visible. Contrast is the difference in image density between two areas. For instance, one area of a scan may be very dark and another very light. Radiog- raphers need contrast in order to spot broken bones or defects on organs. Images can have a high level of contrast or a low level. The difference in the density of two parts of an image is greater in high- contrast images. The higher the contrast, the easier it is to spot problems and abnormalities in a scan. If areas of the subject vary in thickness, the contrast will be greater between those two thicknesses. Additionally, taking an X-ray using low volt- age will create an image with high contrast.

 Nuclear Medicine Objectives • Definition • Principle • Classification • Equipment • Applications.

Definition Radio nuclides or radioisotopes are used in medical field to diagnose and treat. It works on the principle that the injected radionuclide has a tracer which takes it to a target organ. The organ absorbs the substance and radiation is released which can be recorded with organ facts. These details are captured in an image and will give information about the organ.

Figure 4.4 Bone scan in N/M.

Classification Nuclear Medicine is divided into two divisions:

1. SPECT 2. PET. SPECT stands for Single Photon Emission Computerized Tomography. A gamma camera is used and has a sensitive detector able to detect gamma rays during NM investigations. Thallium activated Sodium Iodine is used due to its high sensitivity to gamma radiation. A gamma camera has a head, collimators, detector crystal and an array of photomultiplier tubes, Com- puter interface, Image display system and printing system or archiving/ display system. The gamma rays carrying patient information are fed to the detectors which produce light which is fed to the photomultiplier for enhancement then computer system for image processing and display on the monitor/ print. The energy used is 120–350 kev and the radio isotope is inside the patient’s body or organ.

Positron emission tomography (PET) The radionuclide used decays by emitting positrons which are negatively charged electrons. Very short lived and travel short distances before being stopped. These combine with electron to form two photons with energy of 511 kev and travel perpendicular to each other. SPECT and PET radionuclide inside the patient. Energy ranges differ with SPECT at 120–350 kev and PET 511 kev and the equipment differ slightly in structure and principle. In PET, the part under examination is inside the gantry and surrounded by detectors for image acquisition and archiving. Radio nuclides prepared under aseptic technique in a HOT lab.

Radionuclide SPECT uses Technician 99, Iodine 123 – 3 hours, Iodine 131 8 days, Xenon 133 kev 8 days, Thallium and Indium 111 2–8 days. In PET nuclides are Fluorine 18–110 mins, Oxygen 15–21 mins, Gallium 68 mins, Nitrogen 10 mins, Potassium 38 mins and Copper 62. In the hot laboratory, these are mixed with a molecule or tracer to be specific to the target organ.

NM applications The whole body and in particular the body organs. These are kidneys, liver, thyroid gland, heart, pancreas and lungs. Some nuclides can be taken orally. Radiation protection – very crucial to the public, patients, radiation workers and other patients. Recommendations to be followed like ALARA principle, ICRP and IAEA.  Radiotherapy Objectives • Define radiotherapy • State the types of radiotherapy • Explain the reasons for doing radiotherapy • Identify radiotherapy applications • Explain radiation protection and quality control in radiotherapy.

Definition This is radiation therapy by use of gamma radiation to treat cancer and tumours. Soft radiation also used. Seen as shortening life but it prolongs life and relieves pain and stress. There are two types of treatment apart from chemotherapy and surgery namely: 1. Branch therapy 2. Teletherapy.

Reasons for therapy • To alleviate pain • To stop haemorrhage • Prolong life for a while • Give patient hope • Arrest tumour growth.

Branch therapy The source of radiation is the patient. Radionuclide inserted using aseptic technique and the lesion is the source of radiation. Energies used are to the tune of mega electron volts.

Teletherapy Source is from outside but not within the patient. Linear accelerators used to produce energy of MEV. Simulation is the first step in this kind of treatment. A simulator consists of an X-ray source like CT, MRI or conventional imaging. In simulation, the field size is determined and the target area identified precisely. Dose calculated. Two main concepts used: • Tissue Maximum Ratio (TMR) and • Depth dose.

Applications Radiotherapy is a treatment of choice when surgery and chemotherapy are impossible. It is applied in all body regions like: Head, Neck, Pelvis, Chest, Abdomen and its organs to treat masses of various types. Radiation protection is as for NM. Be aware of disposal procedure for radio nuclide wastes.

 Magnetic Resonance Imaging (MRI) Objectives • Define Magnetic Resonance Imaging • Explain principle of operation in MRI • Define the terms used in MRI • Explain the equipment used • State the coils used in MRI • Explain the types of magnets used in MRI.

Definition This is an imaging modality which uses magnetic field to create images. The body has hydrogen which acts as magnets in the body interact- ing with external radio waves. Longitudinal magnetization occurs when there is equilibrium. Medical use began in 1972. Cooling is done by liquid Helium gas. There is relaxation after excitement. Proton movement called precession or spin.

Equipment The equipment for MRI is similar to CT and includes: Gantry with coolers, detectors, magnet, Magnetic shields for different body parts, Patient table and cradle, Operator console and computer and printer. Applications All body parts as in CT and more sensitive to neurological procedures. These are the spine, brain, chest and abdomen and other body parts. Tesla is the unit of measurement and is equal to 10 kgs. Guess is the smallest unit of measurement. Ranges are 0.3 tesla to 3 tesla hence have 0.3, 0.5, 1, 1.5 and 3.

Operation The higher the magnetic field the higher the precession. Radio frequency make the protons precess in synch (in phase) and opposite ones cancel. RF switched off longitudinal magnetization increase again and this is called longitudinal relaxation (back to normal state) and is defined by a time constant T1. Transversal magnetization decreases and disappear and is called time constant T2. Liquids long relaxation time, T1 long. T1 darker fluids in image and T2 bright – World War 2 – water white.

Images • T1 darker images • T2 white images of fluid • Proton density between T1 and T2 • Time to repeat a pulse at 90 and 180 degrees then tissues have relaxed and at the same state. Figure 4.5 A normal MRI myelography lateral projection Contrast media This increases lesion detection and diagnostic accuracy. Gadolinium and magnevist used and blood appear white when no contrast and dark with contrast. Suppression helps to damp fat and other intervening substances within the body which obscure the needed slices hindering diagnosis.

MRI coils These help in different ways some of which are: • Shim coils – for magnetic field homogeneity • Encoding coils – for the slice thickness • Gradient coils – for slice selection (Noise due to anchorage. Part of machine couch) • Surface coils – for signal reception • Volume coils – surround body part-Send and receive the signals.

Hardware The most important part of MRI machine is the magnet. Earth field is one Gauss and this was a German mathematician who measured geomagnetic field and won a Nobel Prize. Electrical and mechanical adjustment to get field homogeneity is called Shiming.

Magnets for MRI They are three: 1. Permanent magnet – Always ready and no need to magnetize. Has low field strength (0.3 T), environmental interference, thermal instability and too much weight about 100 tones. 2. Resistive magnet – Hybrid and uses current. Low energy (0.3 T), electromagnetic, gets too hot, resist current, cooling needed and environmental interference. 3. Superconducting magnet – Mostly used. Special high current. Electric- ity and gas cooling thus helium and nitrogen (liquid –4 to –296 degrees centigrade). At this point the conductor loses its resistance. The liquid gases for cooling are called Cryogens. Quench This is loss of superconductivity of the magnet. It becomes resistant due to high temperatures. Cryogens boil and pass thro quench lines. If switched off, will be rumped (heat high) and quenched to restore the magnetism.

Advantages of superconducting magnets • High magnetic field 0.5 to 3 tesla • No environmental interference • Homogeneous magnetic field • Good images and high resolution. MRI machine installed away from magnetic objects like computers, met- als, cars and Farady cage used for shielding the machine from other magnetic fields. References

Arvaritis, T.N., Parizel, P.M., Degryse, H.R. and Schepper, A.M.A. 1991. A pilot pro- gramme for image management. European Journal of Radiology, Vol. 12, No 2– 3. Bond, N. 1999. Training of staff. Radiography, Vol. 5, pages 1–60. Burns, J.E. 1999. Radiographic exposure slide rules. The British Journal of Radiology, Vol. 72, pages 48–54. Burns, N. and Grove, S.K. 2005. The practice of nursing research, Elsevier, Missouri, USA. Brennan, P.C. and Nash, M. 1998. Increasing FFD an effective dose reduction tool for lateral lumbar spine investigations. Radiography, Vol. 75, No 4, pages 251– 259. Castle, A.D., Adrian, H., Holloway, D.G. and Race, A.J. 1997. Continuing professional development for radiographers. Radiography, Vol. 3, No 4, pages 253–263. Cathcart, J., Bailie, N., Gallagher, G. and Hill, D. 2002. Helical CT scanning of the nose and paranasal sinuses using a low dose protocol: in comparison to conventional CT. Radiography, Vol. 8, pages 79–83. Chapman, S. and Nakielny, R. 2003. Aids to radiological differential diagnosis, Philadelphia, New Yolk, USA. Dawson, B. and Trapp, R.G. 2001. Basic clinical biostatistics. McGraw-Hill Book Co. Singapore. Dhai, A. and Mason, D.M. 2011. Bioethics, human rights and health law, principles and practice, Juta and company, Cape Town, South Africa. Dominic, U. 1999. Clinical effectiveness, how much radiographers know about it. Radiography, Vol. 5, No 2, pages 79–80.

Dunn, M.A. and Rogers, A.T. 1998. X-ray film analysis as a quality indicator. Radiography, Vol. 4, No 1, pages 29–31. Gould, D., Drey, N. and Berridge, E.J. 2007. Nurses experiences of continuing professional development. Nurses’ Education Today, Vol. 27, pages 602–609. Honda, 1998. Manual for middle level manpower training. Hogg P. and Clerk P.A. 1999. Child protection in radiographic practice. Radiography, Vol. 9, pages 127–137. Johnston, D. and Brennan, P.C. 2002. Radiology. British Journal of Radiology, Vol. 4, pages 75–95. Khalifah, K. and Brindhaban, A. 2004. Comparison between conventional radiography and digital radiography for various kvp and mAs settings using a pelvic phantom. Radiography, Vol. 10, No 2, pages 119–125. Kenneth, K.A. 1998. An evaluation of archival quality of radiographs in Nigeria. Journal of the Australian Institute of Radiography, Vol. 45, No 2, pages 71–96. Landini, L., Ripoli, A., Santarelli M.F. and Postano V. 2009. Biological effects of diagnostic cardiac imaging. Radiography, Vol. 10, pages 1034–1039. Lloyd, P.J. 2001. Quality assurance workbook for radiographers and radiological technologists, WHO, Geneva. Mark, A. and Holger, P. 2002. Radiographic anatomy and interpretation of the mus- culoskeletal system, Birmingham, UK. Marshall, G. and Jonker, L. 2011. An introduction to inferential statistics: A review and practical guide. Radiography, Vol. 17, pages e1–e7. Merrill, V. 1999. Radiographic positions and radiologic procedures, Vol. 3, Mosby, St Louis, Missouri, USA. Minnigh, T.R. and Gallet, J. 2009. Maintaining quality control using a radiological digital X-ray. Journal of Digital Imaging, Vol. 22, pages 84–88. Mouton, J. 2001. How to succeed in your Master’s and Doctoral studies: A South African guide and resource book, Van Schaik, Pretoria, South Africa. Munro, L. 2001a. Quality assurance workbook for radiographers, WHO, Geneva. Munro, L. 2001b. Pattern recognition in diagnostic imaging, WHO, Geneva. Nicholas, B. 1999. Training of radiographers. Radiography, Vol. 5, pages 31–60. NIC, F.A., Ghearr, and Brennan, D.C. 1998. Pattern analysis. Radiography, Vol. 4, pages 70–95. Osei, E.K. and Faulkner, K. 2000. Radiation risks from exposure to diagnostic X-rays. Radiography, Vol. 6, pages 131–144. Palmer, P.E.S. 2003. Manual of diagnostic ultrasound, WHO, Geneva. References

Philips Medical Systems, 1994. The British Journal of Radiology, Vol. 67, pages 741–799. Pongnapang, N. 2005. Practical guidelines for radiographers to improve computed radiography image quality. Biomedical Imaging and Intervention Journal, Vol. 2, pages e2–e12. Reid, L.C., Needham, G., Martin, C.J., Darragh, C.L. and Graham, D.T. 1998. Optimising dose reduction in CT scanning of the paranasal sinuses: a randomized control trial of recommended versus lowest achievable dose protocols. Radiography, Vol. 4, pages 261–268. Rao, E.M., Singh, R.P. and Singh T. 2001. Crucial factor affecting film radiography, Hyderabad, India. Relia Soft Corporation, 2007. Instructional manual. Rushton, V.E., Horner, I.K. and Worthington, H.V. 1999. The quality of panoramic radiographs. British Dental Journal, Vol. 86, pages 630–633. Saunders, M., Philip, I. and Adrian T. 2009. Research methods, Pearson, London, UK. Schandorf, C. and Tetteh, G.K. 1998. Equipment design, maintenance and training of radiographers. British Journal of Radiology, Vol. 71, pages 1040–1048. Seibert, J.A. and Boone, J.M. 2005. X-ray imaging physics for nuclear medicine technologists, Lippincott, Baltimore, America. Sheung-Ling L., Anna, S.M., Wing-tat L., Chi-kwok C, and Ka-yin L. 2004. Reject analysis. A comparison of conventional film-screen radiography and computed radiography with PACS. Radiography, Vol. 10, pages 183–187. Siegel, E.L. and Reiner, B.I. 2003. Computerized medical imaging and graphics. Radi- ography, Vol. 27, pages 101–109. Upton, D. 1999. Clinical effectiveness: How much do radiographers know about and what do they think of the concept. Radiography, Vol. 5, No 2, pages 79–80. Warren, H. 2003: Effective use of ionizing radiation. Australian Journal for Radiog- raphers, Radiation Therapists and Sonographers, Vol. 50, No 1, pages 23–24. WHO, 2003. Radiographic Technique and Projections, Geneva. Williamson, K. and Mundy, L.A. 2010. Graduate radiographers’ expectations for role development – The potential impact of misalignment of extension and valence on staff retention and service provision. Radiography, Vol. 16, pages 40–47. Willis, C.E. 2009. Optimizing digital radiography for children. European Journal of Radiology, Vol. 72, pages 266–269. Zewdeneh, D., Teferi, S. and Admassie, D. 2008. X-ray reject analysis in Tikur, Anbessa and Bethzatha Hospitals. Ethiop Journal Health Dev, Vol. 22, pages 63– 67.