07/10/2014

 Radiology basics  Making X-rays  Digital Imaging  Radiation Safety James Montgomery, DVM, DACVR  Image Quality  Goldilocks histories  Teleradiology services

 Know about different types of digital imaging systems  Have a refreshed knowledge of radiation safety and radiographic technique  Understand why improved quality control at image acquisition can improve report quality and turnaround time  Know the benefits that teleradiology can provide to your practice

1 07/10/2014

 A little simplified, but for our purposes:  mAs  Higher mA = MORE x-rays  Longer exposure time –  Higher radiation dose, greater risk of motion  kVp  Higher kVp = more POWERFUL x-rays  Penetrates tissue better

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 Very important to have good quality radiographs  Radiology is hard enough with good images…  Bad images just make all of our lives harder!  Less confident in your diagnosis  Decreased utility of images as a diagnostic tool  Waste of money  Waste of time  Wasted x-ray photons!

 General Practice X-Rays Sound Waves  Radiography • Radiography • Ultrasound • Fluoroscopy  Ultrasound - becoming more common • Computed Tomography (CT) Electromagnetic Radiation Gamma (mostly) Radiation  Larger private/Academic • Magnetic Resonance Imaging (MRI) • Nuclear Scintigraphy  Computed Tomography (CT) • PET-CT/PET-MRI  Magnetic Resonance Imaging (MRI): larger private/academic  Nuclear Scintigraphy  Fluoroscopy

 PET-CT/PET-MRI: Mainly academic/research

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 Radiographs  opacities: radiopaque, radiolucent  A good general diagnostic tool

 CT  attenuation: hyperattenuating, hypoattenuating  Good for assessing bony structures

 Ultrasound  echogenicity, echotexture  Some soft tissue detail – depends on relative opacities of adjacent structures

 MRI  signal intensity Gas – fat – soft tissue – mineral – metal

 Nuclear medicine  increased uptake/activity

 Film-screen technology  Ability to manipulate the image  In its twilight…  Digital  Multiple people can view same study in multiple areas  More and more practices are joining the digital age  Less spatial resolution than film-screen, but better  No physical file to store/locate contrast resolution  Slight loss of spatial resolution compensated for by being able to manipulate the image on the screen  Ease of sharing information/consulting  Magnify, pan, change contrast

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 Increased workflow  Depending on system…  Initial expense  No need for a darkroom  decreased operating cost  Increased IT needs  Generally higher quality images than film  Need robust backup system  More tolerant of imprecise exposure settings  Should have off-site backup storage  Need to stay current with software updates  Improves image with public/clients

 Picture Archiving and Communication System  Digital Imaging Communications in Medicine  Includes:  File format just like .jpg, .tif, .png, .pdf  Device(s) acquiring the images: radiography unit, ultrasound, etc.  Must have DICOM viewing software to view images  Local image storage server  eFilm, Clear Canvas, Osirix, vendor specific viewers, other free viewers are available  Workstations that can view the images stored on the server  Any computer can be set up as a workstation   Local area network Standardized for medical imaging so that a Canon DR plate, a Toshiba ultrasound, an eFilm workstation and a Philips PACS  Off site backup image storage will all use the same image format and same communication  The DICOM image communication protocol (DICOM compliance) protocol via the internet.

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 Need three components:  Made up of pixels (Picture Elements)  AE Title: Name of the computer, server or imaging device  IP address: Each device has its own number  Port number: Communication port  Smaller the pixel, the better the resolution  Your vendor will help you set this up so that everything  Smaller the pixel, more pixels per image  larger file in your PACS communicates properly. size  Each pixel is assigned a shade of gray (or colour)

300 PIXELS PER INCH 75 PIXELS PER INCH

300 pixels per inch

75 pixels per inch Pixels 16x larger

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 Lossless  Lets the image file be broken into smaller components for transmission and then put back together again exactly as it was.

 Lossy  Compression program alters the individual pixel values and discards “unnecessary” bits of information. Makes the file size smaller and is irreversible on the receiving end. Image source: http://www.verypdf.com/pdfinfoeditor/jpeg-jpeg2k-1.png  Not recommended for diagnostic purposes.

 Can be used with existing x-ray machine  Direct digital (DR)  Most expensive system  Most current plates are wired  Wireless plates are available  Computed radiography (CR)  Improved workflow  Image viewable in ~3 sec  Charge-coupled device (CCD)  Next exposure in 5-15 sec  +/- best image quality http://www.ids-  Almost unlimited use healthcare.com/hospital_management/us/Canon_Medical_Systems/Con sumer_Imaging_Equipment/35_0/g_supplier.html

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 Can be used with existing x-ray machine  Good image quality  Not light sensitive  Good portability  Requires a laser reader  Plate is ‘activated’ for many hours  Doesn’t improve workflow over film/screen  Less expensive than DR  Unless you have a multi-cassette reader  Plates wear out and have to be replaced  ~1 min processing time http://www.flatpaneldr.com/?p=631

X-Rays  Have to buy x-ray machine as a unit  Fluorescent screen converts x-ray photons to light photons Film blackness (optical density)  Light captured by CCD digital Intensifying Correctly exposed camera screen  Prone to image artifacts Fiberoptic  “It’s all about the lens…” Light collection  Zero portability  Lower image quality  Cheapest option Focusing lenses Exposure CCD chip

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Overexposed Film blackness Film blackness (optical density) (optical density)

Underexposed

Exposure Exposure

Film/Screen = narrow margin of error

0.5 mAs 1.0 mAs 2.0 mAs 0.5 mAs 1.0 mAs 2.0 mAs

4.0 mAs 8.0 mAs 16.0 mAs 4.0 mAs 8.0 mAs 16.0 mAs

Adapted from Thrall, ed. Textbook of Veterinary Diagnostic Imaging, 6th ed Adapted from Thrall, ed. Textbook of Veterinary Diagnostic Imaging, 6th ed

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70 kVp 1.5 mAs

70 kVp 6 mAs

0.5 mAs 2 mAs 4 mAs Adapted from Thrall, ed. Textbook of Veterinary Diagnostic Imaging, 6th ed

There is a limit to plate overexposure ‘The plate becomes   ‘saturated’ and Technique is not important with digital radiography anatomy disappears’ FALSE  Radiation exposure is less with digital systems  FALSE  Because of increased exposure tolerance with digital there is a trend towards “if in doubt, burn it out…”  Potential for reduced exposure because a less than optimal radiographic technique can still give a diagnostic quality image.

10 07/10/2014

 Particularly in the abdomen  normal radiographs may not = normal abdomen Ultrasound, CT…MRI, yes, but not that common in  Great for imaging soft tissue private practice yet.  Real time imaging  Can see architecture of organs  Changes in echogenicity  Changes in echotexture  Wall layering/Wall thickness  Nodules within organs

 Upper range of human hearing – 20 kHz  Sound waves sent out from transducer – bounce off  Diagnostic ultrasound – 2-17 MHz tissues and return to transducer  Based on the idea that sound passes through  Structures are placed in the image at different depths based on tissues at a different velocity the length of time of the round trip  Different structures absorb or reflect sound at different intensities  different strength of returning sound waves – represented as varying brightness in image

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 Colour Doppler  Gives you velocity and direction of flow  Angle-dependent

 Power Doppler  No directional or velocity information  Sensitive for detecting low blood flow

 First developed in the 1970’s  Tomographic imaging  No superimposition of structures  Excellent bone detail  Good soft tissue resolution  Excellent ability to manipulate the images  Can reconstruct the raw data in any plane and in different ‘windows’ to emphasize bone or soft tissues

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Lung Soft Tissue Bone

 Naturally occurring:  Terrestrial  Energy that is radiated or transmitted in the form of particles or  Soil and rocks contain waves. radioactive materials  The sun  Cosmic radiation  There is NO safe level of radiation exposure.  Man Made  Nuclear reactor  Linear accelerators  X-ray machines, etc.

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 Depends on the energy of the radiation striking matter

 With sufficient energy, it can physically knock out electrons from  Ionizing radiation can break apart atoms  Ionization water molecules to create free radicals

 Radiation which can ionize atoms is Ionizing Radiation  H2O  H + OH  X-Rays, Gamma rays

 OH + OH  H2O2  Radiation lacking sufficient energy to ionize atoms is Non- ionizing  H2O2 is toxic  Ultrasound, MRI http://www.aquasana.com/images/human.gif

 Always wear lead apron, thyroid shield, and gloves  Effect of radiation on  Never have gloves (or any body of your body parts!) in rapidly reproducing cells is the primary beam the most pronounced  Never just cover your hands with the gloves…  Collimate! – No dog-o-grams or cat-o-grams…  First trimester carries the highest risk  Remember ALARA  Use sedation so you aren’t in the room whenever possible

14 07/10/2014

Radiation Doses Received from Some Familiar Activities

Event Radiation Dose Received (mSv) Flight from LA to Paris 0.05 Thoracic radiograph 0.22 Population Group Dose Limits: Over 5 Yrs Dose Limits: Annual Apollo X astronauts’ 4.8 moon flight Worker 100 mSv 50 mSv Whole-mouth dental x-ray 9.1 Exposure to accident at 11.0 Public - 1 mSv Three Mile Island Mammography 15.0 Barium enema 80.0 Heart catheterization 450.0

Reproduced from Thrall, Textbook of Veterinary Diagnostic Radiology, 5th ed

 Fundamental principle of radiation protection

Three Components:  Limit the amount of time you are exposed  Time  Use chemical restraint so technicians do not need  Distance to be in the room for most radiographs

 We have very good, very safe drugs for sedation – USE  Shielding THEM!!!!

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 Rotate personnel in room  Take advantage of the inverse square law!  Intensity of radiation (x-rays/unit area) decreases with the square of the  Avoid repeat examinations distance from the source  Modern imaging system  Good processing technique  Doubling the distance reduces the x-ray intensity to 1/4th (1/2)2  Personnel training  Accurate technique chart  Tripling the distance reduces the x-ray intensity to 1/9th (1/3)2  Minimize patient holding

 Balance between dose and practice efficiency  Do not hand-hold the x-ray machine or cassette  Holding is not wrong if done correctly

X  Use personal protective X equipment

X  Know the properties of the type of radiation you are  Distance very effective for radiation protection working with so you can  Comes into play if you change the distance choose the proper shield. between x-ray tube and patient  have to calculate new mAs

http://www.doh.wa.gov/ehp/rp/air/air-images/3%20What6.gif

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 Gloves and gowns DO NOT protect from the primary beam  Lead aprons – only protect from scatter radiation  Must be properly cared for to preserve protective capability – hang them up, don’t fold them  Gloves  Thyroid shield  Shielded glasses

 Manually restrict beam to desired size  Use collimation – want 100% - 4 sided collimation  Decreases scattered radiation  Increases image quality  Decreases personnel exposure

BAD GOOD

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 What’s at stake  Professional reputation  Employee health  Your income

 You could be sued

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