GH9800011
RADIATION PROTECTION BOARD
GHANA ATOMIC ENERGY COMMISSION
RADIATION PROTECTION AND SAFETY GUIDE
NO. GRPB-G5
SAFE USE OF X-RAYS
29-39 RADIATION PROTECTION BOARD
GHANA ATOMIC ENERGY COMMISSION
RADIATION PROTECTION AND SAFETY GUIDE
NO. GRPB-G5
SAFE USE OF X-RAYS RPB REPORT NO. GRPB-G5 (1998)
C. Schandorf, E. O. Darko, J. Yeboah, and S. D. Asiamah
RADIATION PROTECTION AND SAFETY GUIDE
NO. GRPB-G5
SAFE USE OF X-RAYS NOTICE OF APPROVAL
By virtue of section 11 of the Radiation Protection Instrument, LI 1559 of 1993 and with the consent of the Ghana Atomic Energy Commission, the Radiation Protection Board has on 1998, approved the Radiation Protection and Safety Guide on Safe Use of X-rays.
This guide is approved for the purposes of providing practical guidance to registrants to fulfill the requirement of the Radiation Protection Instrument LI 1559.
This guide comes into effect on 1998.
Signed:
PROF. S. K. SARPONG DR. P. C. ACQUAH CHAIRMAN CHAIRMAN GHANA ATOMIC ENERGY COMMISSION RADIATION PROTECTION BOARD CONTENTS
Pages FOREWORD v
PREFACE vi
1.0 INTRODUCTION 1
1.1 General 1.2 Scope 1.3 Exemptions
2.0 GENERAL REQUIREMENTS AND ADMINISTRATIVE CONTROLS 1-3
2.1 Registrant's Responsibility 2.2 Shielding 2.3 Prohibitions 2.4 Individual Monitoring and Reporting Requirements 2.5 Records and Associated Information 2.6 Staff Qualifications 2.7 Radiation Safety Procedures 2.8 Radiation Safety Program 2.9 Operator Training
3.0 EQUIPMENT AND OPERATION REQUIREMENTS FOR ALL DIAGNOSTIC X-RAY SYSTEMS 3-6
3.1 Half-Value Layer 3.2 Beam-On Indicators 3.3 Mechanical Support of Tube Head 3.4 Diagnostic Source Assembly Leakage Radiation Limits 3.5 Radiation from Capacitor Energy Storage X-ray Equipment in Standby Status 3.6 Technique Indicators 3.7 Reproducibility of Exposures 3.8 Patient or Film Support 3.9 Personnel Protection 3.10 Technique Guides 3.11 Patient Dose Criteria 3.12 X-ray Film Processing Systems 3.13 Gonadal Shielding 3.14 Viewing and Communication 3.15 Mobile and Portable Control Location
4.0 FLUOROSCOPIC SYSTEMS 6-9 4.1 Beam Limitation 4.2 Spot Film Devices 4.3 Fluoroscopic Timer 4.4 Primary Barrier/Interlock 4.5 Source-Skin Distance (SSD) 4.6 Indication of Potential and Current 4.7 Activation of the Fluoroscopic Tube 4.8 Entrance Exposure Requirements 4.9 Barrier Transmitted Radiation Rate Limits 4.10 Staff and Ancillary Personnel Protection 4.11 Control of Scattered Radiation 4.12 Additional Requirements for Stationery Fluoroscopic Systems used for Cardiac Catheterization Procedures 4.13 Radiation Therapy Simulation Systems 4.14 Operator Restrictions
5.0 RADIOGRAPHIC SYSTEMS OTHER THAN FLUOROSCOPIC, DENTAL OR COMPUTED TOMOGRAPHY SYSTEMS 9-11
5.1 Beam Limitation 5.2 Timer;. 5.3 X-iay Control 5.4 Source-Skin Distance (SSD) 5.5 Linearity 5.6 SID Indication 5.7 X-ray Field/Imaj.;; Receptor Alignment 5.8 Medical Radiographic Entrance Exposure Limits
6.0 REQUIREMENTS FOR FACILITIES PERFORMING MAMMOGRAPHY 11-14
6.1 Physician Supervision 6.2 Radiographist who perform Mammography 6.3 Type of Machine 6.4 Compression Device 6.5 Half-Value Layer 6.6 Source-Imaging Receptor Distance 6.7 Focal Spot Size 6.8 Mammography Exam Dose Limits 6.9 Mammography Exposure Rate 6.10 Mammography Phantom Image Evaluation 6.11 Quality Assurance 6.12 Records
7.0 COMPUTED TOMOGRAPHY (CT SYSTEMS) 14-15
7.1 Requirements for Equipment
iii 7.2 Facility Design Requirements ' 7.3 Quality Assurance 7.4 Records 7.5 Operating Procedures
8.0 DENTAL RADIOGRAPHIC SYSTEMS 15-17
8.1 General Requirements 8.2 Additional Requirements for Dental Intraoral Systems 8.3 Dental Radiographic Exposure Limits (Single Film) 8.4 Beam Limitation Requirements for Dental Extraoral Systems 8.5 Additional Requirements for Dental Radiography
9.0 THERAPY SYSTEMS 17-23
9.1 Facility Design 9.2 Plan Review 9.3 Shielding Requirements s ^ 9.4 Safety Systems 9.5 Operator and Control Position 9.6 Viewing and Communication System 9.7 Warning Signs 9.8 Equipment Requirements 9.9 Radiation Protection Survey 9.10 Calibrations 9.11 Quality Assurance Checks 9.12 Service or Maintenance 9.13 Dosimetry System Requirements 9.14 Records 9.15 Operating Procedures
10.0 NON-MEDICAL X-RAY SYSTEMS 23-25
10.1 Labelling 10.2 Tests and Inspection 10.3 Records 10.4 Additional Operating Procedures and Instructions 10.5 Monitoring in Addition to the Requirements of Section 2.4 10.6 Additional Requirements for Industrial Radiography Units 10.7 Additional Requirements for Baggage Systems 10.8 Additional Requirements for Cabinet Systems
DEFINITIONS 26-27
REFERENCES 27
WORKING GROUP 28 FOREWORD
The Radiation Protection Board (RPB) was established in 1993 by the amendment of the Atomic Energy Act, Act 204 of 1963 by the Provisional National Defence Council Law, Law 308. The Primary Law was strengthened by the enactment of the Radiation Protection Instruments, LI 1559 in January 1993. The RPB is mandated to be the National Competent Authority in Ghana for licensing and inspection of sources and practices for the purposes of radiation safety.
This regulatory guide was developed to assist Registrant to follow systematic procedures which will facilitate an effective implementation of the provisions of the radiation protection regulations.
Preparation of this guide was carried out with the assistance of Illinois Department of Nuclear Safety the support of the Ghana Atomic Energy Commission. PREFACE
In the framework of the IAEA Inter-regional Model Project on Radiation Protection for upgrading of regulatory capability for licensing and inspection, the need to prepare supporting documents such as codes of practice, guides and relevant document was recognized.
X-rays has been used over several decades in Ghana for diagnosis in medicine and other applications in industry, research and teaching without any regulatory guidance on its safe use.
The present guide, GRPB-G5 on Safe use of X-rays is intended to assist registrants to follow systematic procedures for ensuring cost effective and safe use of x-rays in Ghana.
Based upon the review of the legislation in place and other document available the working group decided to follow the format of tae previous Radiation and Safety Guide? prepared with the assistance of International Atomic Energy Agency. The overall system of national regulation is then as follow?/
Level 1 - Ghana Atomic Energy Commission ACT 204 1963 with Amendment:
Atomic Energy Commission LAW, PNDC Law 308 of 1993.
Level 2 - Ghana Radiation Protection INSTRUMENT, LI 1559 of 1993.
Level 3 - Radiation Protection and Safety GUIDES, 1995, with current documents as follows: GRPB-G1 - Qualification and Certification of the Radiation Protection Personnel.
GRPB-G2 - Notification and Authorization by Registration or Licensing. Exemption and Exclusions.
GRPB-G3 - Dose Limits.
GRPB-G4 - Inspection.
GRPB-G5 - Safe Use of X-rays
VI 1.0 INTRODUCTION
1.1 General:
If properly utilized, the use of x-rays can be instrumental in the improvement of the health and welfare of the public. As such, this regulatory guide was developed to assist and encourage registrants in the safe and constructive use of x-rays and to prohibit and prevent exposure to ionizing radiation in amounts which are or may be detrimental to health.
1.2 Scope
The present guide applies to the use of x-rays for diagnostic, therapeutic, and non medical purposes.
1.3 Exemptions
The Radiation Protection Board (RPB) may, upon application or upon its own initiative, grant exemptions of exceptions from the requirements of this regulatory guide if, in the opinion of the RPB, it is impractical to comply, and only if such an exemption or exception will not result in undue hazard to public health and safety.
2.0 GENERAL REQUIREMENTS AND ADMINISTRATIVE CONTROLS
2.1 Registrant's Responsibility
a) Direct the operation of the x-ray system(s);
b) Register with Radiation Protection Board (RPB) in accordance with the provisions of LI 1559 all x-ray equipment which is used;
c) Permit operation of the x-ray systems(s) only by individuals who are authorized in accordance with Radiation Protection and Safety Guide No. GRPB G-2.
2.2 Shielding
Each installation shall be provided with such primary barriers and/or secondary barriers as are necessary to assure compliance with the dose limits provision of Radiation Protection and Safety Guide No. GRPB G-3.
2.3 Prohibitions a) Individuals shall not be exposed to the useful beam except for diagnostic or therapeutic purposes and only when such exposure has been authorized by a medical or dental practitioner registered under the Medical and Dental Degree, 1972 (N.R.C.D. S91). This provision specifically prohibits deliberate exposure of individuals for training, demonstration or other non-medically related purposes; b) Fluoroscopy shall not be used as a substitute for radiography or in lieu of proper anatomical positioning/centering procedures prior to radiographic studies. c) The use of direct exposure x-ray film (without intensifying screens) for routine diagnostic radiological imaging procedures, other than intraoral dental radiography and therapeutic portal imaging, is prohibited.
1 d) The use of photofluorographic systems is prohibited.
2.4 Individual Monitoring and Reporting Requirements
All persons who are associated with the operation of an x-ray system are subject to the radiation dose standards, requirements for the determination of doses, requirements for individual monitoring, and requirements for reporting of radiation doses, which are specified in Radiation Protection and Safety Guide No. GRPB G-3.
2.5 Records and Associated Information
The registrant shall maintain at the facility, for a period of at least one inspection cycle records showing the receipt, transfer, storage and disposal of all sources of radiation.
2.6. Staff Qualifications
The registrant shall maintain at the facility, for review by the RPB, current listing of all authorized users.
2.7 Radiation Safety Procedures
The registrant shall provide to each individual who operates x-ray equipment at the facility written operating and safety procedures.
2.8 Radiation Safety Program
The registrant shalir provide for initial and annual in-service training in radiation safety for individuals (excluding registered practitioners) that apply ionizing radiation at the facility, to ensure their awareness of the registrant's radiation safety practices and policies. The in-service training shall include the following topics:
a) Operating and emergency procedures for the radiation machine(s);
b) Use of personnel and patient protective devices; c) Procedures to minimize patient and occupational doses, including procedures for selecting personnel to support patients or film; d) Use of individual monitoring devices; e) Film processing procedures; and f) Prohibited uses of x-ray machines as described in Section (2.3), above.
2.9 Operator Training
Individuals who operate radiation machines shall be instructed in and able to demonstrate competence with the registrant's operating and safety procedures.
3.0 EQUIPMENT AND OPERATION REQUIREMENTS FOR ALL DIAGNOSTIC X-RAY SYSTEMS
The requirements of this Section apply to all diagnostic x-ray systems. Additional requirements for specific equipment application classes are in Sections (4.0), (5.0), (6.0), (7.0) and (8.0).
3.1 Half-Value Layer
The half-value layer of the useful beam for a given x-ray tube potential shall not be less than the values shown below:
X-Ray Tube Voltage Minimum HVL Minimum HVL (kilovolt peak) (mm of AI) (mm of Al) Designed Measured Dental Systems Other X-Ray Operating range Operating Potential Systems Below 50 30 1.5 0.3 40 1.5 0.4 49 1.5 0.5 50 to 70 50 1.5 1.2 60 1.5 1.3 70 1.5 1.5 Above 71 71 2.1 2.1 80 2.3 2.3 90 2.5 2.5 100 2.7 2.7 110 3 120 3.2
(1) Linear extrapolation or interpolation may be made for an x-ray tube potential (kVp) not listed.
(2) Half-value layer requirements for mammography systems are specified in Section (6.5). 3.2 Beam-On Indicators
The control panel shall include a device (usually a millimetre or labelled indicator lamp) which will give positive indication of the production of x-rays whenever the x-ray tube is energized.
3.3 Mechanical Support of Tube Head
The tube housing assembly supports shall be adjusted such that the tube housing assembly will remain stable during an exposure unless tube housing movement is an designed function of the x-ray system. The tube housing assembly supports shall not be hand-held unless the manufacturer has specifically designed the system to be operated while hand-held.
3.4 Diagnostic Source Assembly Leakage Radiation Limits
The leakage radiation measured at a distance of 1 meter from the source shall not exceed an air kerma rate of lmGy (lOOmR.) in 1 hour when the tube is operated at leakage technique factors.
3.5 Radiation from Capacitor Energy Storage X-ray Equipment in Standby Status
Radiation emitted from the x-ray tube when the exposure switch or tinier is not activated shall not exceed an air kerma rate of 20,uGy (2mR) per hour at 5 centimetres from any accessible surface of the diagnostic sourcs assembly, with the beam-limiting device fully open.
3.6 Technique Indicators
The technique factors to be used during an e> posure shall be indicated at the control panel before the exposure begins. If automatic exposure controls are used, the technique factors which are set prior to the exposure shall be indicated at the control panel. Indication of technique factors shall be visible form the operator's position except in the case of spot films. a) On equipment having fixed technique factors, the requirement of this section may be met by permanent markings. b) The indicated technique factors of exposure time and kilovolts peak (kVp) shall correspond to the actual exposure factors utilized within ten percent of the measured values.
3.7 Reproducibility of Exposures
For any specific combination of selected technique factors, utilized, the coefficient of variation of radiation exposures shall not exceed 0.05 for any specific combination of selected technique factors. a) For systems using automatic exposure control (AEC), compliance measurements shall be performed with appropriate attenuating material placed in the beam to provide exposure times in the range of those used clinically. 3.8 Patient or Film Support
No person shall be used routinely to hold film or patients, and every reasonable effort made to limit such a person's radiation dose.
3.9 Personnel Protection
Except for patients who cannot who cannot be moved out of the room, only the individuals required for the medical procedure or training shall be in the room during the radiographic/fluoroscopic exposure.
a) Individuals who must be in the room with the patient being radiographed or fluoroscoped shall be protected by 0.25 millimeter lead equivalent aprons or shields, or shall be positioned at a distance such that the individual does not receive a radiation dose in excess of the limits specified in Radiation Protection and Safety Guide No. GRPB G-3.
3.10 Technique Guides
In the vicinity of each radiographic x-ray system's control panel, a technique guide shall be provided which specifies, for routine examinations performed, the patient's anatomical size versus technique factors to be utilized, and the source-image distance (SID) to be used.
3.11 Patient Dose Criteria
Procedures and auxiliary equipment designed to minimize patient and occupational dose commeisurate with needed diagnostic information shall be used.
3.12 X-ray Film Processing Systems
Darkroom facilities shall be kept clean and light tight to prevent fogging of unprocessed film. The darkroom safe light illumination shall be adequate for the film speed(s) and the darkroom operating procedures used. The following additional requirements apply to film processing systems:
a) Manual film processing systems shall be monitored by the registrant to assure:
i) The use of a dedicated darkroom timer with an adjustable preset function, which shall be used to adjust film processing time according to solution temperature. ii) The use of a dedicated darkroom thermometer, which shall be used to adjust film processing time according to solution temperature. iii) The use of a film processing guide which shall contain, at a minimum, information regarding time(s) and temperature(s) (as recommended by the processing chemical manufacturer) used by the registrant to develop radiographs. iv) The changing of film processing chemicals at a frequency which is appropriate for the conditions of use. b) Automated film processing shall be monitored by the registrant to assure: i) The temperature of film processing chemicals is appropriate for the type of film(s) being processed, and the film transport speed, ii) The film processing chemicals used and their replenishing rate are appropriate for the film selected.
3.13 Gonadal Shielding
Except for case in which it would interfere with the diagnostic procedure, gonadal shielding of not less than 0.5 millimeter of lead equivalent shall be used for patients (who have not passed the reproductive age) during those radiographic procedures in which the gonads are in the useful beam.
3.14 Viewing and Communication
Windows, mirrors or an equivalent system shall be provided to permit the operator to continuously observe the patient during irradiation. In addition, the operator shall be able to maintain aural contact with the patient.
3.15 Mobile and Portable Control Location
' For mobile and portable single event exposures, the x-ray control shall be positioned so that the operator is at least 1.83 metres (6 feet) away from the tube housing and the patient during an exposure.
4.0 FLUOROSCOPIC SYSTEMS
In addition to the provisions of Sections (2.0) and (3.0), the requirements of this section apply to x-ray equipment and associated facilities used for fluoroscopy.
4.1 Beam Limitation
The x-ray field shall be limited by stepless adjustable shutters to the area of clinical interest for both the fluoroscopic and spot film modes.
a) The mechanism(s) provided for activating and positioning the beam-limiting shutters shall function properly.
4.2 Spot Film Devices
Spot film devices shall meet the following additional requirements:
a) The center of the x-ray field in the plane of the image receptor shall be aligned with the center of the selected portion of the film to within two percent of the SID; and
b) If the angle between the plane of the image receptor and beam axis is variable, a device shall be provided to visually indicate when the axis of the x-ray beam is perpendicular to the plane of the image receptor. 4.3 Fluoroscopic Timer
A manual reset, cumulative timing device shall be used which will either indicate elapsed on- time by an audible signal or turn off the system when the total exposure time exceeds a predetermined limit not exceeding 5 minutes in one or a series of exposures.
4.4 Primary Barrier/Interlock
These devices shall be provided and shall function so that:
a) The entire cross section of the useful beam is intercepted by the primary protective barrier of the fiuoroscopic image assembly at any SID; and
b) The fiuoroscopic tube is interlocked to prevent the unit from producing x-rays unless the primary barrier is in position to intercept the useful beam at all times.
4.5 Source-Skin Distance (SSD)
The SSD shall not be less than:
a) 38 centimeters on all stationary fluoroscopes; and
b) 20 centimeters on all mobile fluoroscopes.
4.6 Indication of Potential and Current
During fluoroscopy and recording of fluoroscopy images, the kVp and the mA shall be continuously indicated at the control panel and/or the operator's position.
4.7 Activation of the Fiuoroscopic Tube
X-ray production in the fluoroscopic mode shall be controlled by a device which requires continuous pressure by the operator for the entire time of any exposure. When recording serial fluoroscopic images, the operator shall be able to terminate the x-ray exposure(s) at any time, but means may be provided to permit completion of any single exposure of the series in process.
4.8 Entrance Exposure Requirements a) Maximum Exposure Rate. Fluoroscopic systems shall not be operable at any combination of tube potential and current which will result in an air kerma rate in excess of 1 OOmGy (10R) per minute at the point where the center of the useful beam enters the patient, except:
i) During recording of fluoroscopic images; or ii) When an optional high level control is activated. b) When a high level control is activated, the equipment shall not be operable at any combination of tube potential and current which will result in an air kerma rate in excess 200mGy (20 R) per minute at the point where the center of the useful beam enters the patient. In addition, the following requirements apply to high level controls:
i) Separate means of activation of high level controls shall be required and operable only when continuous manual activation is provided by the operator. ii) A continuous signal audible to the operator shall indicate that the high level control is being employed.
4.9 Barrier Transmitted Radiation Rate Limits
The air kerma rate due to transmission through the primary protective barrier shall not exceed 20,uGy (2mR) per hour at 10 centimeters from any accessible surface of the fluoroscopic imaging assembly beyond the plane of the image receptor per lOmGy (1R) per minute of entrance air kerma rate.
4.10 Staff and Ancillary Personnel Protection
The operator, assistants and observers allowed in the examining room shall be protected from scatter radiation by protective aprons of not less than 0.25 millimetre lead equivalent or whole body protective barriers, or shall be positioned at a sufficient distance to ensure ^hat the individual does not receive a radiation dose in excess of the limiis specified ir> Radiation Protection Safety Guide No. GRPB-G3.
4.11 Control of Scattered Radiation a) For fluoroscopic systems utilizing an x-ray tube that is mounted below the table, the table shall be provided with shielding (bucky slot cover) equivalent to 0.25 millimeter lead equivalent to attenuate scattered radiation emanating from below the table. b) Except where sterile fields or special procedures prohibit the use, a shield of at least 0.25 millimeter lead equivalent, such as overlapping protective drapes or hinged or sliding panels, shall be provided and used to intercept scatter radiation which would otherwise reach the operator and others near the machine. This shielding shall not be a substitute for the wearing of a protective apron (0.25 millimeter lead equivalent) for protection against scattered radiation.
4.12 Additional Requirements for Stationery Fluoroscopic Systems Used for Cardiac Catheterization Procedures a) Protective barriers shall be available for use by individuals whose presence is required in the room during activation of the x-ray tube(s). If a protective barrier includes or consists of a transparent viewing panel, the viewing panel shall afford protection of not less than 0.5 millimeter of lead equivalent. b) Protection aprons of not less than 0.25 millimeter of lead equivalent shall be worn in the fluoroscopy room by all individuals (except the patient). 4.13 Radiation Therapy Simulation Systems
Radiation therapy simulation systems shall be exempt from the requirements of Sections (4.1), (4.3), (4.4), (4.8) and (4.9) above provided that:
a) Such systems are designed and used in such a manner that no individual other than the patient is in the x-ray room during periods of time when the system is producing x-rays; and
b) Such systems that do not meet the requirements of (4.3) above are provided with a means of indicating the cumulative time that an individual patient has been exposed to x-rays. Procedures shall require in such cases that the timer be reset between examinations.
4.14 Operator Restrictions
No person shall intentionally administer radiation to a human being with a fluoroscopic radiation machine unless such person is registered physician, except:
a) An authorized Radiographist may operate a tluoroscope for radiation therapy simulation procedures under the direct supervision of a registered practitioner.
5.0 RADIOGRAPHIC SYSTEMS OTHER THAN FLUOROSCOPIC, DENTAL, OR COMPUTED TOMOGRAPHY SYSTEMS
In addition to the provisions of Sections (2.0) and (3.0), requirements of this section apply to x- ray equipment and associated facilities used in the healing arts of medicine. It does not apply to fluoroscopic, dental, or computed tomography systems.
5.1 Beam Limitation
The useful beam shall be limited to the area of clinical interest. This can be met with: a) An adjustable collimator with means for defining the perimeter of the x-ray field; b) An assortment of removable, fixed-aperture, beam-limiting devices sufficient to meet the requirement for each combination of image receptor size and SID for which the unit is use shall have, permanent, clearly legible markings, in centimeters and/or inches, which indicate the image receptor size and SID for which each aperture is designed.
5.2 Timers
Means shall be provided to terminate the exposure at a preset timer interval, preset product of current and time, preset number of pulses or preset radiation exposure to the image receptor. Also, it shall not be possible to make an exposure when the timer is set to a zero or off position. 5.3 X-ray Control
An x-ray control shall be incorporated into each x-ray systems such that an exposure can be terminated by the operator at any time except for: exposures of 0.5 second or less; or during serial radiography when means shall be provided to permit completion of any single exposure of the series in process.
5.4 Source-Skin Distance (SSD)
All mobile or portable radiographic systems shall be provided with means to limit the SSD to 30 centimeters or greater.
5.5 Linearity
For equipment which is operated at more than one x-ray tube current setting, the average ratios of air kerma (exposure) to the indicated milliampere-seconds (mAs) product obtained at any two tube current settings utilized shall not differ by more than 0.10 times their sum. This requiiement is mathematically represented by the following:
where x, and x2 are the average iu.Gylm.hs or mR/mAs values obtained at any two tube current settings utilized.
5.6 SID Indication
.ms shall be provided to indicate the SID in centimeters and/or inches and the measured SID shall correspond to the indicated value to within two percent.
5.7 X-ray Field/Image Receptor Alignment
Means shall be provided to: indicate when the axis of the x-ray field is perpendicular to the plane of the image receptor, and to align the center of the x-ray field with respect to the center of the image receptor to within two percent of the SID.
5.8 Medical Radiographic Entrance Exposure Limits
The in-air entrance surface dose determined for the technique used for the specified average adult patient for routine medical radiography shall not exceed the dose exposure limits shown below:
10 Technique Thickness Entrance Surface Dose Limit (cm) (mGy) (mR) Chest 23 0.4 40 Chest (LAT) 23 1.5 150 Abdomen (AP) 23 10 1000 Lumbo-Sacral Spine (AP) 23 10 1000 Skull (LAT) 15 3.0 300 Skull (PA) - 5.0 50 Pelvis (AP) - 10.0 1000
These limits are maximums. With careful selection of technique factors, adjustment of film processing systems, and choice of film and screen-film combinations, patient exposures can be further reduced.
6.0 REQUIREMENTS FOR FACILITIES PERFORMING MAMMOGRAPHY
In addition to the provisions of Sections (2.0), (3.0), and (5.0) the requirements of this section apply to mammography systems and associated facilities used for mammography.
6.1 Physician Supervision
Mammography operations and procedures shall be under the supervision of a physician.
6.2 Radiographist who perform Mammography
Registrants shall ensure that radiographist who perform mammography procedures have met the requirements for initial training listed below:
Subject Hours of Instruction Anatomy and Physiology of the Breast 1 Hour Mammographic Equipment and Technique 1 Hour Mammographic Quality Control 2 Hour Positioning Techniques for Mammography 2 Hour Mammographic Film Evaluation 1 Hour Special Procedures in Breast Imaging 1 Hour
6.3 Type of Machine
Mammography shall only be performed with a special purpose radiation machine specifically designed for mammography procedures.
11 6.4 Compression Device
Mammography systems shall be provided with compression devices parallel to the imaging plane to immobilize and compress the breast. Compression devices shall be capable of maintaining a compression force of at least 11.3 kilograms (25 pounds) for at least 15 seconds; and not be capable of exceeding a compression force of more than 18.1 kilograms (40 pounds) when used in an automatic or power drive mode.
6.5 Half-Value Layer
For mammography systems operating at x-ray tube potentials of less than 35 kVp, the half-value layer (HVL) in millimeters of aluminium of the useful beam shall be equal to or greater than the product of the tube potential in kilovolts multiplied by 0.01.
6.6 Source-Imaging Receptor Distance
Mammography equipment shall not be operated at any source-image receptor distance less than 50 centimeters. l
6.7 Focal Spot Size
The nominal focal spot size, as specified by the x-ray tube manufacturer, shal' not exceed 0.6 millimeter.
6.8 Mammography Exam Dose Limits
The mean glandular dose for one craniocaudal view of a 4.2 centimeter compressed breast (iO percent adipose and 50 percent glandular) shall not exceed: a) lmGy screen-film radiographs not employing the use of grids. b) 3mGy for screen-film radiographs employing the use of grids.
6.9 Mammography Exposure Rate
Mammography systems shall have sufficient x-ray output to complete the exposure required for the dose measurement of Section (6.8) above within a time of 2.5 seconds or less.
6.10 Mammography Phantom Image Evaluation
Mammography equipment shall be subjected to a phantom image evaluation using the mammography phantom specified below: a) The mammography phantom used for phantom image evaluation shall be composed of material that is equivalent to a nominal 4.2 centimeter compressed breast of average density (i.e., 50 percent adipose and 50 percent glandular tissue) and shall contain the following objects:
12 i) Spherical masses, composed of phenolic plastic, with thickness of: 2.00, 1.00, 0.75, 0.50 and 0.25 millimeter; ii) Specks, composed of aluminum oxide, with diameters of: 0.54, 0.40, 0.32, 0.24 and 0.16 millimeter; and iii) Fibers, composed of nylon, with thicknesses of: 1.56, 1.12, 0.89, 0.75, 0.54 and 0.40 millimeter.
b) The mammography system shall be capable of producing images of the mammography phantom in which the following objects are visualized:
i) The three largest masses with thicknesses of 2.0, 1.0 and 0.75 millimeter. ii) The three largest speck groups with diameters of 0.54, 0.40 and 0.32 millimeter. iii) The four largest fibers with thicknesses of 1.56, 1.12, 0.89 and 0.75 millimeter.
6.11 Quality Assurance
A quality assurance (QA) programme shall be established and maintained at each facility performing mammography procedures. The QA' programme shall include a performance evaluation of the mammographic x-ray machine and the film processor. Each facility shall have available for daily use the mammography phantom specified in (6.10a).
a) A radiological physicist shall establish and provide administrative oversight over the quality assurance programme, and conduct an ? imual review.
b) Quality assurance testing shall include, but not be limited to, the following tests, which shall be performer\ at the prescribed frequency.
i) The film processor shall be subjected to a performance evaluation each day before the processing of clinical or phantom images. Evaluation shall include measurement of temperature and film quality, ii) Mammography systems shall be tested for image quality each calendar month. Image quality testing shall be performed using the mammography phantom specified above. c) The following requirements apply to image quality testing:
i) The individual assigned to perform phantom image quality evaluation shall be adequately trained, ii) Image quality testing shall be repeated after any change in or replacement of components of the x-ray machine or film processor which may affect the image quality, iii) Each phantom image produced shall be labelled with the date, technique factors and equipment information if the facility contains more than one mammography unit, iv) The registrant shall assure that the phantom image produced pursuant to this subsection meets the criteria of Section (6.10b) above, v) Mammography systems not capable of producing a phantom image meeting the
13 above criteria shall not be used to image human patients until an adequate phantom image has been produced.
6.12 Records a) The registrant shall maintain and have available for review at the facility, for at least one inspection cycle, records of quality assurance testing performed.
7.0 COMPUTED TOMOGRAPHY (CT SYSTEMS)
7.1 Requirements for Equipment a) Termination of Exposure
i) In the event of equipment failure affecting data collection, means shall be provided to terminate the x-ray exposure automatically, either by de-energizing the x-ray source or by shuttering the x-ray beam, through the use of either a back- up timer or devices which monitor equipment function. A visible signal shall indicate wiien the x-ray exposure has been terminated. ii) The operator shall e able to terminate the x-ray exposure at any time during a scan, or series of scans, of greater than 0.5 second duration. b) Tomographic Plane Indiction and Alignment
i) Means shall be provided to permit visual determination of the location of a reference plane. If a device using a light source is used, the light source shall provide illumination levels sufficient to permit visual determination of the location of the tomographic plane or reference plane. ii) The total error in the indicated location of the tomographic plane or reference plane shall not exceed 5 millimeters. iii) The deviation of indicated scan increment versus actual increment shall not exceed plus or minus 1 millimeter with a typical patient mass resting on the patient support device. The patient support device shall be moved incrementally from a typical starting position to the maximum incremental distance or 30 centimeters, whichever is less, and then returned to the starting position. If the CT system has the capability of variable gantry angles, the compliance measurements shall be performed with the CT gantry positioned at zero degrees. c) The CT x-ray control panel and gantry shall provide visual indication whenever x-rays are produced and if applicable, whether the shutter is open or closed. d) The CT x-ray control panel shall provide visual indication of the technique factors, tomographic section thickness, and scan increment prior to the initiation of a scan or a series of scans.
14 7.2 Facility Design Requirements
a) The control panel shall be located behind a protective barrier.
b) Provision shall be made for two-way aural communication between the patient and the operator at the control panel.
c) Windows, mirrors or an equivalent system shall be provided to permit continuous observation of the patient during irradiation and shall be located so that the operator can observe the patient from the control panel.
7.3 Quality Assurance
Quality Assurance procedures shall be conducted on each CT system and shall meet the following requirements: a) The quality assurance procedures shall be in writing and such procedures shall include, but need not be limited to, the following: ;•
i) Specifications of the tests that are to be performed, including instructions to be employed in the performance of those tests; and ii) Specifications of the frequency at which tests are to be performed, the acceptable tolerance for each parameter measured and actions to be taken if tolerances are exceeded. b) Quality assurance procedures shall include acquisition of images using a CT phantom which has the capability of providing an indication of the resolution capability of the system.
7.4 Records
The registrant shall maintain for at least one inspection cycle and have available for review at the facility, records of quality assurance testing performed.
7.5 Operating Procedures
Information shall be available at the control panel regarding the operation of the system. Such information shall include written quality assurance procedures, as required.
8.0 DENTAL RADIOGRAPHIC SYSTEMS
In addition to the provisions of Sections (2.0 and (3.0) the requirements of this section apply to x-ray equipment and associated facilities used for dental radiography.
8.1 General Requirements a) Means shall be provided to terminate the exposure at a preset time interval, preset product
15 of current and time, preset number of pulses or preset radiation exposure to the image receptor. Also, it shall not be possible to make an exposure when the timer is set to a zero or off position if either position is provided. b) An x-ray control shall be incorporated into each x-ray system such that an exposure can be terminated by the operator at any time except for exposures of 0.5 second or less. c) The exposure switch shall be a dead-man switch and shall be arranged so that the operator can be behind a protective barrier or at least 1.83 meters (6 feet) from the patient and the tube housing during an exposure.
8.2 Additional Requirements for Dental Intraoral Systems a) Source-Skin Distance (SSD). X-ray systems designed for use with an intraoral image receptor shall be provided with means to limit the SSD to not less than:
i) 18 centimeters if operable above 50 kVp; or ii) 10 centimeters if operable at 50k Vp and below. b) Beam Limitation. Radiographic systems designed for use with an intraoral image receptor "hall be provided with means to limit the x-ray beam such that the x-ray field, at the minimum SSD, shall be containable in a circle having a diameter of no mce than 7 centimeters.
8.J Dental Radiographic Exposure Limits (Single Film)
The entrance exposure to an adult patient for routine intraoral exams shall not exceed tne limit specified in the table below:
Entrance Surface Dose Limits Examination (mGy) (mR) Periapical 7 700
AP 5 500
8.4 Beam Limitation Requirements for Dental Extraoral Systems a) Dental rotational panoramic systems shall be provided with means to limit the x-ray beam to the imaging slit in the transverse axis and shall not exceed a total of 13 millimeters (0.5 inch) larger than the imaging slit in the vertical axis. b) All other dental extraoral radiographic systems (e.g. cephalometric) shall be provided with means to both size and align the x-ray field so that it does not extend beyond any edge of the image receptor by more than two percent of the SID.
16 8.5 Additional Requirements for Dental Radiography
a) Patient and film holding devices shall be used when the techniques permit;
b) The tube housing and the position indicating device shall not be hand-held during an exposure;
c) The x-ray system shall be operated in such a manner that the useful beam a the patient's skin does not exceed the criteria specified in 8.2 (b).
d) The operator shall be behind a protective barrier or be provided with a protective apron of not less than 0.25 millimeter lead equivalent during an exposure. Individuals whose presence is required in the room during an x-ray examination shall be protected from leakage and scatter radiation by protective aprons of not less than 0.25 millimeter lead equivalent, a protective barrier, or shall be positioned at a sufficient distance to ensure that the individual does not receive a radiation dose in excess of the limits specified in Radiation Protection and Safety Guide No. GRPB-G3.
9.0 THERAPY SYSTEMS
In addition to th? provisions of Section (2.0), the requirements of this section apply to x-ray therapy systems and associated facilities.
9.1 Facility Design
A radiological physicist sh -11 be consulted in the design of an x-ray therapy installation,
9.2 Plan Review
For all x-ray therapy systems capable of operating above 150 kVp, facility design information shall be submitted to the RPB for review prior to installation. Information submitted shall include, but need not be limited to, the following: a) Name and address of the planned installation. b) Name, address and telephone number of the radiological physicist who was consulted in the design of the installation. c) A scale drawing that includes the location of the therapy system, control panel and doors to the room. d) The structural composition and thickness of all walls, doors, partitions, floor and ceiling of the installation. e) The occupancy of areas adjacent to the installation. f) Calculations that demonstrate the adequacy of the amount of shielding specified for each
17 primary and secondary protective barrier, g) Projected weekly dose rates in areas adjacent to the installation.
9.3 Shielding Requirements i) Each x-ray therapy installation shall be provided with such primary and secondary barriers as are necessary to assure compliance with Radiation Protection and Safety Guide No. GRPB-G3.
9.4 Safety Systems a) X-ray therapy systems operating at greater than 150 kVp shall have an interlock installed on each door of the therapy room. The interlock shall be wired into the electrical circuit in such a manner that when the door is opened, for any reason, the generation of x-rays will automatically be terminated and irradiation can be resumed only by manually resetting the controls on the control panel after the door is closed. b) The doors to the therapy room shall be designed and installed to allow opening from the inside at all times. c) X-ray therapy systems operating above 150 kVp, and all therapy rooms to which access is possible through more than one entrance shall be provided with warning lights in a readily observable position near the outside of all access doors. The warning lights shall indicate when the UL^ful beam is on.
9.5 Operator and Control Position a) For x-ray therapy systems operating at 150 kVp and below, the control panel and operator shall be located either outside the therapy room or behind a protective barrier within the room. b) For x-ray therapy systems operating above 150 kVp, the control panel and operator shall be located outside the therapy room.
9.6 Viewing and Communication System
Windows, mirrors, closed-circuit television or an equivalent system shall be provided to permit continuous visual observation of the patient during irradiation and shall be located so that the operator can observe the patient from the control panel. In addition, the facility design shall permit two-way aural communications between the patient and the operator at the control panel.
9.7 Warning Signs
Each radiation area shall be conspicuously posted with a radiation caution sign which is appropriate for the radiation levels encountered.
18 9.8 Equipment Requirements a) When the tube is operated at its maximum rated continuous current for the maximum rated tube potential, the leakage radiation shall not exceed the value specified in the table below at the distance specified in the table for the classification of that x-ray system. Radiation measurements shall be average over an area up to, but not exceeding, 100 square centimeters.
X-Ray System Leakage Limit Measurement Location 1 mGy 5 centimeters from Contact Therapy (0.1 R) per hour the tube housing
100 mGy (1R) 1 meter from 0 - 499 kVp per hour the source
0.1 percent of useful beam or 1 meter from 500 kVp - 999 kVp 100 mGy (1 R) per hour, the source whichever is greater b) Permanent fixed diapiiragms or cones used for limiting the useful beam shall provide the same or a higher degree of protection as required for the tube housing assembly. Removable beam-limiting devices shall, for the portion of the useful beam to be blocked by these devices, transmit not more than one percent of the useful beam at the maximum kilovoltage and maximum treatment filter. c) The filter system shall be designed so that the filters are securely positioned and will not become dislodge when the machine is positioned at any possible orientation. In addition:
i) The of air kerma at one meter from the filter insertion slot opening does not exceed 100 mGy (1R) per hour when the machine is operated at its maximum current and maximum tube potential; ii) Each filter is labelled with its composition and thickness (for wedge filters, the wedge angle and maximum design field size shall appear on the wedge or wedge tray); iv) If the x-ray therapy system uses changeable filters, there is a filter indication system which permits recognition of any added filter in place and indicates from the control panel the presence or absence of a particular filter. d) The x-ray tube shall be mounted so that it cannot turn or slide with respect to the housing aperture. e) The tube housing shall remain stable during treatment unless tube housing movement is a designed function of the system. f) Mean shall be provided to indicate the Source-Skin Distance (SSD) in centimeters and/or inches and the measured SSD shall correspond to the indicated value to within 0.5
19 percent. g) A timer, which has a display at the control panel, shall be provided and shall meet the following requirements:
i) The timer shall be activated with the production of radiation; ii) For systems equipped with a shutter mechanism to control irradiation, the timer shall be activated when the shutter is opened; iii) The timer shall terminate irradiation when a pre-selected time has elapsed; iv) The timer shall permit presetting and determination of exposure times at least as short as I second; and v) The timer shall not permit an exposure if the operator has not selected a time for the exposure. h) The control panel, in addition to the displays required in other provisions of this Section, shall have an indication of whether x-ray are being produced, a means for indicating x-ray tube potential and current, and a means for terminating an exposure at any time. i) For equipment that is provided with shutters, the shutters shall have a lead equivalency ,iot less than that of the tube housing assembly be controlled electrically by the operator at the control panel, and provide an indication of shutter pos'tion at the control panel. j) For control panels capable of energizing ^lore than one x-ray tube, it shall be possible to energize only one x-ray tube at anytime. There shall also be an indication at the control panel and tube housing assembly which identifies which tube is energized. h) Each x-ray therapy system equipped with a beryllium window shall be clearly labelled as such upon the tube housing assembly and at the control panel.
9.9 Radiation Protection Survey
A radiation protection survey shall be performed by a radiological physicist on each x-ray therapy system before the therapy system is first used for irradiation of a patient. Such a survey shall also be performed after any change in the x-ray therapy system or facility that might produce a radiation hazard, and done so before the therapy system is again used to treat patients. The registrant shall maintain at the facility a copy of the most recent radiation protection survey report for review by the RPB. a) Survey reports shall include, but need not be limited to the following:
i) A diagram of the facility which details building structures and the position of the control panel, x-ray therapy system and associated equipment; ii) A description of the x-ray therapy system including the manufacturer, model number and range of kilo volt potential; iii) A description of the instrumentation used to determine radiation measurements, including the date and source of the most recent calibration for each instrument used;
' 20 iv) Condition under which radiation measurements were taken; and v) Survey data including projected weekly dose equivalent in areas adjacent to the therapy room, a description of workload, and the use and occupancy factors employed in determining the projected weekly dose equivalent.
b) The registrant shall retain a copy of the radiation protection survey report and a copy of the report shall be provided to the RPB within 30 days of completion of the survey.
c) Any deficiencies detected during the radiation protection survey that would constitute or result in a violation of Radiation Protection and Safety Guide No. GRPB-3 shall be corrected prior to using the machine for treatment of patients.
d) The facility shall be operated in compliance with any limitations indicated by the radiological physicist as a result of the radiation protection survey required by the RPB.
9.10 Calibrations
Each x-ray therapy system shall be calibrated by a radiological physicist before the therapy system is first used for irradiation of a patient. The calibration of the x-ray therapy system shall include, but need not be limited to, determination of the following:
a) The radiation output, expressed as air kerma rate or absorbed dose rate in tissue, as a function of distance, field size, x-ray tube potential and current, filters and treatment applicators used; b) The half-value layer for each kilovoltage setting and filter combination used; c) The degree of congruence between the radiation field and the field indicated by each beam-limiting device; and d) An evaluation of the uniformity of the radiation field.
9.11 Quality Assurance Checks
Quality assurance checks shall be made by a radiological physicist at intervals not to exceed 1 year. Quality assurance checks shall include, but need not be limited to, determination of the radiation output for a set of operating conditions specified by the radiological physicist and the coincidence of the radiation field and the field indicated by the beam-limiting device, except for systems equipped with fixed diaphragms or cones. a) The radiological physicist shall establish criteria for quality assurance check measurements and shall determine corrective actions to be implemented if the criteria are exceeded.
9.12 Service or Maintenance
Whenever service or maintenance is performed on the therapy system, a radiological physicist
21 shall be notified and shall determine whether a calibration or quality assurance check is necessary to verify the characteristics of the beam.
9.13 Dosimetry System Requirements
Measurements of the radiation output of the x-ray therapy system shall be performed using a dosimetry system that has been calibrated by an approved calibration laboratory using a radiation beam of comparable half-value layer to the x-ray system to be calibrated. The dosimetry system shall meet one of the two conditions below: a) The calibration of the dosimetry system shall have been performed within the previous 2 years and after any servicing that may have affected the calibration of the dosimetry system; or b) The dosimetry system shall have been calibrated within the previous 4 years and shall have been subjected to a protocol which provides for checks of dosimetry constancy and provides for corrective action when results deviate by more than two percent from the expected values.
9.14 Records .
The registrant shuil maintain at the facility record machine calibrations, quality assurance checks and instrument calibrations for inspection by the RPB for a period of 5 years. Records to be maintained by the registrant shall include, but need not be limited to the following: a) Records of machine calibration and quality assurance checks shall include identification of the x-ray therapy system, radiation measurements, the date the measurements were performed and the signature of the therapeutic radiological physicist who performed the measurements. b) Instrument calibration records shall include the date of the last calibration and identity of the calibration laboratory. If a dosimetry system has been subjected to a protocol as described in subsection above, 9.13 (b) records shall be maintained that show the date and results of each constancy check performed on the system.
9.15 Operating Procedures a) No x-ray therapy system shall be left unattended unless the system is secured against unauthorized use. b) When a patient must be held in position for radiation therapy, mechanical supporting or restraining devices shall be used. c) Other than the patient, no individual shall be in the therapy room unless such individual is protected by a barrier sufficient to meet the requirements of Radiation Protection and Safety Guide No. GRPB-G3.
22 d) Other than the patient, no individual shall be in the therapy room during exposure from x-ray therapy systems operating above 150 kVp.
e) The x-ray therapy system shall not be used for treatment of patients unless the operator can maintain visual observation of the patient and audible communication with the patient.
f) The tube housing assembly shall not be held by hand during operation unless the x-ray therapy system is designed to require such holding and the peak tube potential of the system does not exceed 50 kilovolts. In such cases, the person holding the tube shall wear protective gloves and apron of not less than 0.5 millimeter lead equivalency at 100 kVp.
10.0 NON-MEDICAL X-RAY SYSTEMS
In addition to the requirements of Section 2.0, this section establishes special requirements for analytical x-ray machines, cabinet/baggage, and industrial radiography units and associated facilities.
• 1 10.1 Labelling
a) A label bearing the words "Caution - Radiation - This Equipment Produces Radiation When Energized" shall be placed near any switch which energizes a tube.
b) A sign bearing the words "Caution - High Intensity X-ray Beam", or words having a similar intent, shall be placed in the area immediately adjacent to each tube head. The sign shall be so located that it is clearly visible to any person operating, aligning, or adjusting the unit, or handling or changing a sample.
c) A clearly visible indication of the presence of an x-ray beam shall be provided on or immediately adjacent to each tube head.
d) A clearly visible indication of the status (i.e., open or closed) of each shutter if applicable shall be provided .
10.2 Tests and Inspection
Tests and inspections of all safety devices shall be performed at least monthly to insure their proper operation. Surveys and monitoring sufficient to insure that operations are conducted safely shall also be provided.
10.3 Records
Records of tests and inspections, surveys and monitoring sufficient to show compliance to the RPB's regulations shall be maintained and kept available for inspection.
23 10.4 Additional Operating Procedures and Instructions a) Individuals having access to non-medical machines or equipment shall be provided with specific written instructions concerning the radiation hazards, safe working practices and made aware of the symptoms of an acute localized exposure to radiation. These instruction shall be posted near the controls of the x-ray machine(s). b) Medical personnel examining work-connected injuries shall be informed of the possibility of radiation exposure to the worker from the devices regulated in this section. c) Operators shall be instructed in the procedures for reporting an actual or suspected radiation overexposure. When it has been determined that an overexposure to an individual has occurred, it shall be reported to the RPB without undue delay. d) In cases where the primary x-ray beam is not intercepted by the experimental apparatus under all conditions of operation, protective measures shall be provided, such as auxiliary shielding, to avoid exposure TO the primary x-ray beam. e) If, for any reason, it is necessary to temporarily iutentionally alter safety devices, such as bypassing interlocks or removing shielding, such action shall be specified in writing ana posted near the x-ray tube housing so that other persons will know the existing status of the machine; and terminated as sooa as possible. f) Whenever possible, an interlocking device which prevents the entry of any portion of an individual body or extremities into the primary beam, or causes the primary beam to be shv •. off upon entry into its path, shall be provided. g) Unused tube ports shall be closed in such a fashion that accidental opening is not possible.
10.5 Monitoring in Addition to the Requirements of Section 2.4
Operators of non-medical x-ray equipment shall be provided with finger radiation monitoring devices if the equipment is not provided with interlocks as specified in section 10.4(f).
10.6 Additional Requirements for Industrial Radiography Units
The following additional requirements apply to x-ray systems and associated facilities used for industrial radiography: a) The control panel shall be equipped with a locking device to prevent unauthorized use, as well as a device which will provide positive indication of the production of x-ray whenever the radiation machine is energized. b) During each radiographic operation, the operator shall maintain direct surveillance of the area to protect against unauthorized entry.
24 c) Each radiation area shall be conspicuously posted with a radiation caution sign which is appropriate for the radiation levels encountered. In addition, whenever practical, ropes or barriers shall be used in addition to appropriate signs, to designate radiation areas and to help prevent unauthorized entry.
d) Enclosed radiography systems shall also contain:
i) Audible and visible alarms which can be activated prior to each exposure; ii) A door, which can be opened from within the room, containing an interlock system which will prevent entry or stop an exposure.
e) Open radiography systems shall have available a properly calibrated survey instrument appropriate for the range of use.
10.7 Additional Requirements for Baggage Systems
The following additional requirements apply to baggage x-ray systems:
a) An operator is required at the control area, who must maintain surveillance of all openings during x-ray generation.
b) The control panel must contain an exposure switch of the dead man type, with means to terminate the exposure at any time.
10.8 Additional Requirement for Cabinet Systems
The following additional requirements apply to cabinet x-ray systems: a) Insertion of any body part into the primary beam is prevented. b) Safety interlocks interrupt x-ray production whenever the door is opened.
25 DEFINITIONS
The following definitions apply for the purpose of this guide:
"Aluminum equivalent" means the thickness of type 1100 aluminum alloy affording the same attenuation, under specified conditions, as the material in question. The nominal chemical composition of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12 percent copper.
"Analytical x-ray machine" means any machine utilizing x-rays for examination of the microscopic structure, or elemental or chemical composition of materials. This includes all types of x-ray diffraction and spectrographic/fluorescence equipment.
"Board" means the Radiation Protection Board of the Ghana Atomic Energy Commission.
"Cabinet x-ray system" means an x-ray system with the x-ray tube installed in an enclosure which is intended to contain at least that portion of a material being irradiated, provide radiation attenuation and exclude personnel from its interior during ger oration of x-radiation. Included are all x-ray systems designed primarily for the inspection of carry-on baggage at airline terminals.
"Collimaior" means a device or mechanism by which the x-ray beam is restricted in size.
"Computed tomography (CT)" means the production of a tomogram by the acquisition and computer processing of x-ray transmission data.
"Contact therapy system" means an x-ray system used for therapy which is designed for very short treatment distances (5 centimeters or less), usually employing peak tube potentials in the rangeof20to50kVp.
"Dead-man switch" means a switch constructed so that a circuit-closing contact can be maintained only by continuous pressure on the switch by the operator.
"Enclosed radiography" means industrial radiography conducted in an enclosed room.
"Facility" means an assembly of devices, equipment, structures or natural features whether simple or complex, which serves some specific purpose or performs some other function.
"Industrial radiography" means the process used to perform the examination of the macroscopic structure of materials by non-destructive methods using radioactive material or radiation machines.
"Kilovolts peak (kVp)" means the crest value, in kilovolts, of the electric potential applied to the x-ray tube between the cathode and anode of a pulsating electric potential generator.
"Leakage radiation" means all radiation emanating from the diagnostic source assembly except for the useful beam and the radiation produced when the exposure switch or timer is not
26 activated.
"Mammography" means radiography of the breast for the purpose of enabling a physician to determine the presence, size, location and extent of cancerous or potentially cancerous tissue in the breast.
"Radiation therapy simulation system" means a radiographic/fluoroscopic x-ray system used exclusively for localizing the volume to be exposed during radiation therapy and confirming the position and size of the therapeutic irradiation field.
"Radiological Physicist" means an individual who has the knowledge, training and experience to measure ionizing radiation, evaluate safety techniques, advise regarding radiation protection and quality assurance needs and apply the principles of radiological physics to diagnostic x-ray or radiation therapy applications.
REFERENCES
[1] Ghana Atomic Energy Commission ACT, Act 204 of 1963 with Amendment: Atomic Energy Commission LAW, Law 308 of 1993.
[2] Ghana Radiation Protection INSTRUMENT, LI 1559 1993. Arrangement of Regulation.
[3] International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, April 1994.
[4] Illinois Department of Nuclear Safety Regulations 32 Illinois Administrative Code Chapter II Part 360 360-1 - 380-2 (1995).
[5] Radiation Protection and Safety GUIDES, 1995, GRPB-G1, Qualification and Certification of the Radiation Protection Personnel.
[6] Radiation Protection and Safety GUIDES, 1995, GRPB-G2, Notification and Authorization by Registration or Licensing. Exemption and Exclusions.
[7] Radiation Protection and Safety GUIDES, 1995, GRPB-G3, Dose Limits.
[8] Radiation Protection and Safety GUIDES, 1995, GRPB-G4, Inspection.
27 WORKING GROUP (1-13 March 1998, Legon, Ghana)
1. Brown, P. X-ray Expert, Chief of Illinois Department of Nuclear Safety,
Division of Electronics Products
2. Schandorf, C. Director, Radiation Protection Board (RPB)
3. Darko, E. O. Head, Radiation Protection Board (RPB) Laboratories
4. Yeboah, J. Radiation Protection Board
5. Asiamah, S. D. Radiation Protection Board
6. Akoto, G. E. Chief Technician, Radiation Protection Board
7. Asamoah, D. (Miss) Secretary
28