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GH9800011
RADIATION PROTECTION BOARD
GHANA ATOMIC ENERGY COMMISSION
RADIATION PROTECTION AND SAFETY GUIDE
NO. GRPB-G5
SAFE USE OF X-RAYS
2 9 - 3 9
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. ACQUAHCHAIRMAN CHAIRMANGHANA ATOMIC ENERGY COMMISSION RADIATION PROTECTION BOARD
CONTENTS
PagesFOREWORD v
PREFACE vi
1.0 INTRODUCTION 1
1.1 General1.2 Scope1.3 Exemptions
2.0 GENERAL REQUIREMENTS ANDADMINISTRATIVE CONTROLS 1-3
2.1 Registrant's Responsibility2.2 Shielding2.3 Prohibitions2.4 Individual Monitoring and Reporting Requirements2.5 Records and Associated Information2.6 Staff Qualifications2.7 Radiation Safety Procedures2.8 Radiation Safety Program2.9 Operator Training
3.0 EQUIPMENT AND OPERATION REQUIREMENTS FOR ALLDIAGNOSTIC X-RAY SYSTEMS 3-6
3.1 Half-Value Layer3.2 Beam-On Indicators3.3 Mechanical Support of Tube Head3.4 Diagnostic Source Assembly Leakage Radiation Limits3.5 Radiation from Capacitor Energy Storage X-ray Equipment
in Standby Status3.6 Technique Indicators3.7 Reproducibility of Exposures3.8 Patient or Film Support3.9 Personnel Protection3.10 Technique Guides3.11 Patient Dose Criteria3.12 X-ray Film Processing Systems3.13 Gonadal Shielding3.14 Viewing and Communication3.15 Mobile and Portable Control Location
4.0 FLUOROSCOPIC SYSTEMS 6-9
4.1 Beam Limitation4.2 Spot Film Devices4.3 Fluoroscopic Timer4.4 Primary Barrier/Interlock4.5 Source-Skin Distance (SSD)4.6 Indication of Potential and Current4.7 Activation of the Fluoroscopic Tube4.8 Entrance Exposure Requirements4.9 Barrier Transmitted Radiation Rate Limits4.10 Staff and Ancillary Personnel Protection4.11 Control of Scattered Radiation4.12 Additional Requirements for Stationery Fluoroscopic Systems
used for Cardiac Catheterization Procedures4.13 Radiation Therapy Simulation Systems4.14 Operator Restrictions
5.0 RADIOGRAPHIC SYSTEMS OTHER THAN FLUOROSCOPIC,DENTAL OR COMPUTED TOMOGRAPHY SYSTEMS 9-11
5.1 Beam Limitation5.2 Timer;.5.3 X-iay Control5.4 Source-Skin Distance (SSD)5.5 Linearity5.6 SID Indication5.7 X-ray Field/Imaj.;; Receptor Alignment5.8 Medical Radiographic Entrance Exposure Limits
6.0 REQUIREMENTS FOR FACILITIES PERFORMINGMAMMOGRAPHY 11-14
6.1 Physician Supervision6.2 Radiographist who perform Mammography6.3 Type of Machine6.4 Compression Device6.5 Half-Value Layer6.6 Source-Imaging Receptor Distance6.7 Focal Spot Size6.8 Mammography Exam Dose Limits6.9 Mammography Exposure Rate6.10 Mammography Phantom Image Evaluation6.11 Quality Assurance6.12 Records
7.0 COMPUTED TOMOGRAPHY (CT SYSTEMS) 14-15
7.1 Requirements for Equipment
iii
7.2 Facility Design Requirements '7.3 Quality Assurance7.4 Records7.5 Operating Procedures
8.0 DENTAL RADIOGRAPHIC SYSTEMS 15-17
8.1 General Requirements8.2 Additional Requirements for Dental Intraoral Systems8.3 Dental Radiographic Exposure Limits (Single Film)8.4 Beam Limitation Requirements for Dental Extraoral Systems8.5 Additional Requirements for Dental Radiography
9.0 THERAPY SYSTEMS 17-23
9.1 Facility Design9.2 Plan Review9.3 Shielding Requirements s ^9.4 Safety Systems9.5 Operator and Control Position9.6 Viewing and Communication System9.7 Warning Signs9.8 Equipment Requirements9.9 Radiation Protection Survey9.10 Calibrations9.11 Quality Assurance Checks9.12 Service or Maintenance9.13 Dosimetry System Requirements9.14 Records9.15 Operating Procedures
10.0 NON-MEDICAL X-RAY SYSTEMS 23-25
10.1 Labelling10.2 Tests and Inspection10.3 Records10.4 Additional Operating Procedures and Instructions10.5 Monitoring in Addition to the Requirements of Section 2.410.6 Additional Requirements for Industrial Radiography Units10.7 Additional Requirements for Baggage Systems10.8 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 theRadiation Protection Personnel.
GRPB-G2 - Notification and Authorization byRegistration 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 andwelfare of the public. As such, this regulatory guide was developed to assist and encourageregistrants in the safe and constructive use of x-rays and to prohibit and prevent exposure toionizing 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 medicalpurposes.
1.3 Exemptions
The Radiation Protection Board (RPB) may, upon application or upon its own initiative, grantexemptions of exceptions from the requirements of this regulatory guide if, in the opinion of theRPB, it is impractical to comply, and only if such an exemption or exception will not result inundue 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 LI1559 all x-ray equipment which is used;
c) Permit operation of the x-ray systems(s) only by individuals who are authorized inaccordance 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 arenecessary to assure compliance with the dose limits provision of Radiation Protection andSafety Guide No. GRPB G-3.
2.3 Prohibitions
a) Individuals shall not be exposed to the useful beam except for diagnostic or therapeuticpurposes and only when such exposure has been authorized by a medical or dentalpractitioner registered under the Medical and Dental Degree, 1972 (N.R.C.D. S91). Thisprovision 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 properanatomical positioning/centering procedures prior to radiographic studies.
c) The use of direct exposure x-ray film (without intensifying screens) for routine diagnosticradiological imaging procedures, other than intraoral dental radiography and therapeuticportal 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 radiationdose standards, requirements for the determination of doses, requirements for individualmonitoring, and requirements for reporting of radiation doses, which are specified in RadiationProtection 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 recordsshowing 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 allauthorized users.
2.7 Radiation Safety Procedures
The registrant shall provide to each individual who operates x-ray equipment at the facilitywritten operating and safety procedures.
2.8 Radiation Safety Program
The registrant shalir provide for initial and annual in-service training in radiation safety forindividuals (excluding registered practitioners) that apply ionizing radiation at the facility, toensure their awareness of the registrant's radiation safety practices and policies. The in-servicetraining 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 selectingpersonnel 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 ALLDIAGNOSTIC X-RAY SYSTEMS
The requirements of this Section apply to all diagnostic x-ray systems. Additional requirementsfor 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 thevalues shown below:
DesignedOperating range
Below 50
50 to 70
Above 71
X-Ray Tube Voltage(kilovolt peak)
MeasuredOperating Potential
30
40
49
50
60
70
71
80
90
100
110
120
Minimum HVL(mm of AI)
Dental Systems
1.5
1.5
1.5
1.5
1.5
1.5
2.1
2.3
2.5
2.7
Minimum HVL(mm of Al)
Other X-RaySystems
0.3
0.4
0.5
1.2
1.3
1.5
2.1
2.3
2.5
2.7
3
3.2
(1) Linear extrapolation or interpolation may be made for an x-ray tube potential (kVp) notlisted.
(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) whichwill 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 willremain stable during an exposure unless tube housing movement is an designed function of thex-ray system. The tube housing assembly supports shall not be hand-held unless themanufacturer 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 airkerma 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 shallnot exceed an air kerma rate of 20,uGy (2mR) per hour at 5 centimetres from any accessiblesurface 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 beforethe exposure begins. If automatic exposure controls are used, the technique factors which are setprior to the exposure shall be indicated at the control panel. Indication of technique factors shallbe 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 metby permanent markings.
b) The indicated technique factors of exposure time and kilovolts peak (kVp) shallcorrespond to the actual exposure factors utilized within ten percent of the measuredvalues.
3.7 Reproducibility of Exposures
For any specific combination of selected technique factors, utilized, the coefficient of variationof radiation exposures shall not exceed 0.05 for any specific combination of selected techniquefactors.
a) For systems using automatic exposure control (AEC), compliance measurements shallbe performed with appropriate attenuating material placed in the beam to provideexposure 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 tolimit 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 individualsrequired for the medical procedure or training shall be in the room during theradiographic/fluoroscopic exposure.
a) Individuals who must be in the room with the patient being radiographed or fluoroscopedshall be protected by 0.25 millimeter lead equivalent aprons or shields, or shall bepositioned at a distance such that the individual does not receive a radiation dose inexcess 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 beprovided which specifies, for routine examinations performed, the patient's anatomical sizeversus 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 dosecommeisurate 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 darkroomoperating procedures used. The following additional requirements apply to film processingsystems:
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, whichshall 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 filmprocessing 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 theprocessing chemical manufacturer) used by the registrant to develop radiographs.
iv) The changing of film processing chemicals at a frequency which is appropriatefor 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 appropriatefor the film selected.
3.13 Gonadal Shielding
Except for case in which it would interfere with the diagnostic procedure, gonadal shielding ofnot less than 0.5 millimeter of lead equivalent shall be used for patients (who have not passedthe reproductive age) during those radiographic procedures in which the gonads are in the usefulbeam.
3.14 Viewing and Communication
Windows, mirrors or an equivalent system shall be provided to permit the operator tocontinuously observe the patient during irradiation. In addition, the operator shall be able tomaintain 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 theoperator is at least 1.83 metres (6 feet) away from the tube housing and the patient during anexposure.
4.0 FLUOROSCOPIC SYSTEMS
In addition to the provisions of Sections (2.0) and (3.0), the requirements of this section applyto 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 forboth the fluoroscopic and spot film modes.
a) The mechanism(s) provided for activating and positioning the beam-limiting shuttersshall 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 thecenter 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 deviceshall be provided to visually indicate when the axis of the x-ray beam is perpendicularto 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 apredetermined 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 barrierof the fiuoroscopic image assembly at any SID; and
b) The fiuoroscopic tube is interlocked to prevent the unit from producing x-rays unless theprimary 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 becontinuously 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 requirescontinuous pressure by the operator for the entire time of any exposure. When recording serialfluoroscopic images, the operator shall be able to terminate the x-ray exposure(s) at any time, butmeans 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 combinationof 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; orii) 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 excess200mGy (20 R) per minute at the point where the center of the useful beam enters thepatient. In addition, the following requirements apply to high level controls:
i) Separate means of activation of high level controls shall be required and operableonly when continuous manual activation is provided by the operator.
ii) A continuous signal audible to the operator shall indicate that the high levelcontrol is being employed.
4.9 Barrier Transmitted Radiation Rate Limits
The air kerma rate due to transmission through the primary protective barrier shall not exceed20,uGy (2mR) per hour at 10 centimeters from any accessible surface of the fluoroscopic imagingassembly beyond the plane of the image receptor per lOmGy (1R) per minute of entrance airkerma rate.
4.10 Staff and Ancillary Personnel Protection
The operator, assistants and observers allowed in the examining room shall be protected fromscatter radiation by protective aprons of not less than 0.25 millimetre lead equivalent or wholebody protective barriers, or shall be positioned at a sufficient distance to ensure ^hat theindividual does not receive a radiation dose in excess of the limiis specified ir> RadiationProtection 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 tableshall be provided with shielding (bucky slot cover) equivalent to 0.25 millimeter leadequivalent 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 0.25millimeter lead equivalent, such as overlapping protective drapes or hinged or slidingpanels, shall be provided and used to intercept scatter radiation which would otherwisereach the operator and others near the machine. This shielding shall not be a substitutefor the wearing of a protective apron (0.25 millimeter lead equivalent) for protectionagainst scattered radiation.
4.12 Additional Requirements for Stationery Fluoroscopic Systems Used for CardiacCatheterization Procedures
a) Protective barriers shall be available for use by individuals whose presence is requiredin the room during activation of the x-ray tube(s). If a protective barrier includes orconsists of a transparent viewing panel, the viewing panel shall afford protection of notless than 0.5 millimeter of lead equivalent.
b) Protection aprons of not less than 0.25 millimeter of lead equivalent shall be worn in thefluoroscopy 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 thepatient 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 meansof 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 radiationmachine unless such person is registered physician, except:
a) An authorized Radiographist may operate a tluoroscope for radiation therapy simulationprocedures 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 tofluoroscopic, 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 therequirement for each combination of image receptor size and SID for which the unit isuse shall have, permanent, clearly legible markings, in centimeters and/or inches, whichindicate 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 ofcurrent 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 beterminated by the operator at any time except for: exposures of 0.5 second or less; or during serialradiography when means shall be provided to permit completion of any single exposure of theseries in process.
5.4 Source-Skin Distance (SSD)
All mobile or portable radiographic systems shall be provided with means to limit the SSD to 30centimeters or greater.
5.5 Linearity
For equipment which is operated at more than one x-ray tube current setting, the average ratiosof air kerma (exposure) to the indicated milliampere-seconds (mAs) product obtained at any twotube current settings utilized shall not differ by more than 0.10 times their sum. This requiiementis mathematically represented by the following:
where x, and x2 are the average iu.Gylm.hs or mR/mAs values obtained at any two tube currentsettings utilized.
5.6 SID Indication
.ms shall be provided to indicate the SID in centimeters and/or inches and the measured SIDshall 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 planeof the image receptor, and to align the center of the x-ray field with respect to the center of theimage 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 adultpatient for routine medical radiography shall not exceed the dose exposure limits shown below:
10
Technique
ChestChest (LAT)Abdomen (AP)Lumbo-Sacral Spine (AP)Skull (LAT)Skull (PA)Pelvis (AP)
Thickness(cm)
2323232315--
Entrance Surface(mGy)
0.41.5
10103.05.0
10.0
Dose Limit(mR)
40150
10001000300
501000
These limits are maximums. With careful selection of technique factors, adjustment offilm processing systems, and choice of film and screen-film combinations, patientexposures 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 sectionapply 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 therequirements 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 specificallydesigned for mammography procedures.
11
6.4 Compression Device
Mammography systems shall be provided with compression devices parallel to the imaging planeto immobilize and compress the breast. Compression devices shall be capable of maintaininga compression force of at least 11.3 kilograms (25 pounds) for at least 15 seconds; and not becapable of exceeding a compression force of more than 18.1 kilograms (40 pounds) when usedin 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-valuelayer (HVL) in millimeters of aluminium of the useful beam shall be equal to or greater than theproduct 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 than50 centimeters. l
6.7 Focal Spot Size
The nominal focal spot size, as specified by the x-ray tube manufacturer, shal' not exceed 0.6millimeter.
6.8 Mammography Exam Dose Limits
The mean glandular dose for one craniocaudal view of a 4.2 centimeter compressed breast (iOpercent 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 forthe 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 themammography phantom specified below:
a) The mammography phantom used for phantom image evaluation shall be composed ofmaterial that is equivalent to a nominal 4.2 centimeter compressed breast of averagedensity (i.e., 50 percent adipose and 50 percent glandular tissue) and shall contain thefollowing 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, 0.24and 0.16 millimeter; and
iii) Fibers, composed of nylon, with thicknesses of: 1.56, 1.12, 0.89, 0.75, 0.54 and0.40 millimeter.
b) The mammography system shall be capable of producing images of the mammographyphantom 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 facilityperforming mammography procedures. The QA' programme shall include a performanceevaluation of the mammographic x-ray machine and the film processor. Each facility shall haveavailable for daily use the mammography phantom specified in (6.10a).
a) A radiological physicist shall establish and provide administrative oversight over thequality assurance programme, and conduct an ? imual review.
b) Quality assurance testing shall include, but not be limited to, the following tests, whichshall be performer\ at the prescribed frequency.
i) The film processor shall be subjected to a performance evaluation each day beforethe processing of clinical or phantom images. Evaluation shall includemeasurement 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 phantomspecified above.
c) The following requirements apply to image quality testing:
i) The individual assigned to perform phantom image quality evaluation shall beadequately trained,
ii) Image quality testing shall be repeated after any change in or replacement ofcomponents of the x-ray machine or film processor which may affect the imagequality,
iii) Each phantom image produced shall be labelled with the date, technique factorsand equipment information if the facility contains more than one mammographyunit,
iv) The registrant shall assure that the phantom image produced pursuant to thissubsection meets the criteria of Section (6.10b) above,
v) Mammography systems not capable of producing a phantom image meeting the
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above criteria shall not be used to image human patients until an adequatephantom image has been produced.
6.12 Records
a) The registrant shall maintain and have available for review at the facility, for at least oneinspection 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 beprovided to terminate the x-ray exposure automatically, either by de-energizingthe 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 shallindicate 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 areference plane. If a device using a light source is used, the light source shallprovide illumination levels sufficient to permit visual determination of thelocation of the tomographic plane or reference plane.
ii) The total error in the indicated location of the tomographic plane or referenceplane shall not exceed 5 millimeters.
iii) The deviation of indicated scan increment versus actual increment shall notexceed plus or minus 1 millimeter with a typical patient mass resting on thepatient support device. The patient support device shall be moved incrementallyfrom a typical starting position to the maximum incremental distance or 30centimeters, whichever is less, and then returned to the starting position. If theCT system has the capability of variable gantry angles, the compliancemeasurements 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-raysare 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 aseries of scans.
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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 theoperator at the control panel.
c) Windows, mirrors or an equivalent system shall be provided to permit continuousobservation of the patient during irradiation and shall be located so that the operator canobserve the patient from the control panel.
7.3 Quality Assurance
Quality Assurance procedures shall be conducted on each CT system and shall meet thefollowing 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 beemployed in the performance of those tests; and
ii) Specifications of the frequency at which tests are to be performed, the acceptabletolerance for each parameter measured and actions to be taken if tolerances areexceeded.
b) Quality assurance procedures shall include acquisition of images using a CT phantomwhich has the capability of providing an indication of the resolution capability of thesystem.
7.4 Records
The registrant shall maintain for at least one inspection cycle and have available for review at thefacility, records of quality assurance testing performed.
7.5 Operating Procedures
Information shall be available at the control panel regarding the operation of the system. Suchinformation 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 tox-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
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of current and time, preset number of pulses or preset radiation exposure to the imagereceptor. Also, it shall not be possible to make an exposure when the timer is set to a zeroor off position if either position is provided.
b) An x-ray control shall be incorporated into each x-ray system such that an exposure canbe 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 operatorcan be behind a protective barrier or at least 1.83 meters (6 feet) from the patient and thetube 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 imagereceptor shall be provided with means to limit the SSD to not less than:
i) 18 centimeters if operable above 50 kVp; orii) 10 centimeters if operable at 50k Vp and below.
b) Beam Limitation. Radiographic systems designed for use with an intraoral imagereceptor "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 than7 centimeters.
8.J Dental Radiographic Exposure Limits (Single Film)
The entrance exposure to an adult patient for routine intraoral exams shall not exceed tne limitspecified 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 beamto the imaging slit in the transverse axis and shall not exceed a total of 13 millimeters (0.5inch) larger than the imaging slit in the vertical axis.
b) All other dental extraoral radiographic systems (e.g. cephalometric) shall be providedwith means to both size and align the x-ray field so that it does not extend beyond anyedge of the image receptor by more than two percent of the SID.
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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 anexposure;
c) The x-ray system shall be operated in such a manner that the useful beam a the patient'sskin 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 apronof not less than 0.25 millimeter lead equivalent during an exposure. Individuals whosepresence is required in the room during an x-ray examination shall be protected fromleakage and scatter radiation by protective aprons of not less than 0.25 millimeter leadequivalent, a protective barrier, or shall be positioned at a sufficient distance to ensurethat the individual does not receive a radiation dose in excess of the limits specified inRadiation 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-raytherapy 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 informationshall be submitted to the RPB for review prior to installation. Information submitted shallinclude, 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 inthe design of the installation.
c) A scale drawing that includes the location of the therapy system, control panel and doorsto the room.
d) The structural composition and thickness of all walls, doors, partitions, floor and ceilingof 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
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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 secondarybarriers as are necessary to assure compliance with Radiation Protection and Safety GuideNo. GRPB-G3.
9.4 Safety Systems
a) X-ray therapy systems operating at greater than 150 kVp shall have an interlock installedon each door of the therapy room. The interlock shall be wired into the electrical circuitin such a manner that when the door is opened, for any reason, the generation of x-rayswill automatically be terminated and irradiation can be resumed only by manuallyresetting 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 theinside at all times.
c) X-ray therapy systems operating above 150 kVp, and all therapy rooms to which accessis possible through more than one entrance shall be provided with warning lights in areadily observable position near the outside of all access doors. The warning lights shallindicate when the UL̂ 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 operatorshall be located either outside the therapy room or behind a protective barrier within theroom.
b) For x-ray therapy systems operating above 150 kVp, the control panel and operator shallbe located outside the therapy room.
9.6 Viewing and Communication System
Windows, mirrors, closed-circuit television or an equivalent system shall be provided topermit continuous visual observation of the patient during irradiation and shall be locatedso that the operator can observe the patient from the control panel. In addition, thefacility design shall permit two-way aural communications between the patient and theoperator at the control panel.
9.7 Warning Signs
Each radiation area shall be conspicuously posted with a radiation caution sign which isappropriate for the radiation levels encountered.
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9.8 Equipment Requirements
a) When the tube is operated at its maximum rated continuous current for the maximumrated tube potential, the leakage radiation shall not exceed the value specified in the tablebelow 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, 100square centimeters.
X-Ray System
Contact Therapy
0 - 499 kVp
500 kVp - 999 kVp
Leakage Limit
1 mGy(0.1 R) per hour
100 mGy (1R)per hour
0.1 percent of useful beam or100 mGy (1 R) per hour,whichever is greater
Measurement Location
5 centimeters fromthe tube housing
1 meter fromthe source
1 meter fromthe source
b) Permanent fixed diapiiragms or cones used for limiting the useful beam shall provide thesame 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 blockedby these devices, transmit not more than one percent of the useful beam at the maximumkilovoltage and maximum treatment filter.
c) The filter system shall be designed so that the filters are securely positioned and will notbecome 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 notexceed 100 mGy (1R) per hour when the machine is operated at its maximumcurrent and maximum tube potential;
ii) Each filter is labelled with its composition and thickness (for wedge filters, thewedge angle and maximum design field size shall appear on the wedge or wedgetray);
iv) If the x-ray therapy system uses changeable filters, there is a filter indicationsystem which permits recognition of any added filter in place and indicates fromthe 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 housingaperture.
e) The tube housing shall remain stable during treatment unless tube housing movement isa designed function of the system.
f) Mean shall be provided to indicate the Source-Skin Distance (SSD) in centimeters and/orinches and the measured SSD shall correspond to the indicated value to within 0.5
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percent.
g) A timer, which has a display at the control panel, shall be provided and shall meet thefollowing 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; andv) 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-raytube 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 operatorat 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 toenergize only one x-ray tube at anytime. There shall also be an indication at the controlpanel and tube housing assembly which identifies which tube is energized.
h) Each x-ray therapy system equipped with a beryllium window shall be clearly labelledas 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 therapysystem before the therapy system is first used for irradiation of a patient. Such a survey shall alsobe performed after any change in the x-ray therapy system or facility that might produce aradiation hazard, and done so before the therapy system is again used to treat patients. Theregistrant shall maintain at the facility a copy of the most recent radiation protection survey reportfor 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 thecontrol panel, x-ray therapy system and associated equipment;
ii) A description of the x-ray therapy system including the manufacturer, modelnumber 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 instrumentused;
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iv) Condition under which radiation measurements were taken; andv) Survey data including projected weekly dose equivalent in areas adjacent to the
therapy room, a description of workload, and the use and occupancy factorsemployed in determining the projected weekly dose equivalent.
b) The registrant shall retain a copy of the radiation protection survey report and a copy ofthe 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 orresult in a violation of Radiation Protection and Safety Guide No. GRPB-3 shall becorrected prior to using the machine for treatment of patients.
d) The facility shall be operated in compliance with any limitations indicated by theradiological 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 therapysystem is first used for irradiation of a patient. The calibration of the x-ray therapy system shallinclude, 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 afunction of distance, field size, x-ray tube potential and current, filters and treatmentapplicators 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 eachbeam-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 1year. Quality assurance checks shall include, but need not be limited to, determination of theradiation output for a set of operating conditions specified by the radiological physicist and thecoincidence of the radiation field and the field indicated by the beam-limiting device, except forsystems equipped with fixed diaphragms or cones.
a) The radiological physicist shall establish criteria for quality assurance checkmeasurements and shall determine corrective actions to be implemented if the criteria areexceeded.
9.12 Service or Maintenance
Whenever service or maintenance is performed on the therapy system, a radiological physicist
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shall be notified and shall determine whether a calibration or quality assurance check is necessaryto 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 adosimetry system that has been calibrated by an approved calibration laboratory using a radiationbeam of comparable half-value layer to the x-ray system to be calibrated. The dosimetry systemshall meet one of the two conditions below:
a) The calibration of the dosimetry system shall have been performed within the previous2 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 shallhave been subjected to a protocol which provides for checks of dosimetry constancy andprovides for corrective action when results deviate by more than two percent from theexpected values.
9.14 Records .
The registrant shuil maintain at the facility record machine calibrations, quality assurance checksand instrument calibrations for inspection by the RPB for a period of 5 years. Records to bemaintained by the registrant shall include, but need not be limited to the following:
a) Records of machine calibration and quality assurance checks shall include identificationof the x-ray therapy system, radiation measurements, the date the measurements wereperformed and the signature of the therapeutic radiological physicist who performed themeasurements.
b) Instrument calibration records shall include the date of the last calibration and identityof the calibration laboratory. If a dosimetry system has been subjected to a protocol asdescribed in subsection above, 9.13 (b) records shall be maintained that show the date andresults 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 againstunauthorized use.
b) When a patient must be held in position for radiation therapy, mechanical supporting orrestraining devices shall be used.
c) Other than the patient, no individual shall be in the therapy room unless such individualis protected by a barrier sufficient to meet the requirements of Radiation Protection andSafety Guide No. GRPB-G3.
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d) Other than the patient, no individual shall be in the therapy room during exposure fromx-ray therapy systems operating above 150 kVp.
e) The x-ray therapy system shall not be used for treatment of patients unless the operatorcan maintain visual observation of the patient and audible communication with thepatient.
f) The tube housing assembly shall not be held by hand during operation unless the x-raytherapy system is designed to require such holding and the peak tube potential of thesystem does not exceed 50 kilovolts. In such cases, the person holding the tube shall wearprotective 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 foranalytical x-ray machines, cabinet/baggage, and industrial radiography units and associatedfacilities.
• 1
10.1 Labelling
a) A label bearing the words "Caution - Radiation - This Equipment Produces RadiationWhen 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 asimilar intent, shall be placed in the area immediately adjacent to each tube head. Thesign shall be so located that it is clearly visible to any person operating, aligning, oradjusting 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 orimmediately adjacent to each tube head.
d) A clearly visible indication of the status (i.e., open or closed) of each shutter if applicableshall be provided .
10.2 Tests and Inspection
Tests and inspections of all safety devices shall be performed at least monthly to insure theirproper operation. Surveys and monitoring sufficient to insure that operations are conductedsafely shall also be provided.
10.3 Records
Records of tests and inspections, surveys and monitoring sufficient to show compliance to theRPB's regulations shall be maintained and kept available for inspection.
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10.4 Additional Operating Procedures and Instructions
a) Individuals having access to non-medical machines or equipment shall be provided withspecific written instructions concerning the radiation hazards, safe working practices andmade aware of the symptoms of an acute localized exposure to radiation. Theseinstruction shall be posted near the controls of the x-ray machine(s).
b) Medical personnel examining work-connected injuries shall be informed of the possibilityof 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 suspectedradiation overexposure. When it has been determined that an overexposure to anindividual 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 apparatusunder all conditions of operation, protective measures shall be provided, such as auxiliaryshielding, to avoid exposure TO the primary x-ray beam.
e) If, for any reason, it is necessary to temporarily iutentionally alter safety devices, such asbypassing interlocks or removing shielding, such action shall be specified in writing anaposted near the x-ray tube housing so that other persons will know the existing status ofthe machine; and terminated as sooa as possible.
f) Whenever possible, an interlocking device which prevents the entry of any portion of anindividual body or extremities into the primary beam, or causes the primary beam to beshv •. off upon entry into its path, shall be provided.
g) Unused tube ports shall be closed in such a fashion that accidental opening is notpossible.
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 monitoringdevices 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 forindustrial 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-raywhenever the radiation machine is energized.
b) During each radiographic operation, the operator shall maintain direct surveillance of thearea to protect against unauthorized entry.
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c) Each radiation area shall be conspicuously posted with a radiation caution sign which isappropriate for the radiation levels encountered. In addition, whenever practical, ropesor barriers shall be used in addition to appropriate signs, to designate radiation areas andto 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 instrumentappropriate 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 allopenings during x-ray generation.
b) The control panel must contain an exposure switch of the dead man type, with means toterminate 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.
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DEFINITIONS
The following definitions apply for the purpose of this guide:
"Aluminum equivalent" means the thickness of type 1100 aluminum alloy affording the sameattenuation, under specified conditions, as the material in question. The nominal chemicalcomposition of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12 percentcopper.
"Analytical x-ray machine" means any machine utilizing x-rays for examination of themicroscopic structure, or elemental or chemical composition of materials. This includes all typesof 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 whichis intended to contain at least that portion of a material being irradiated, provide radiationattenuation and exclude personnel from its interior during ger oration of x-radiation. Includedare all x-ray systems designed primarily for the inspection of carry-on baggage at airlineterminals.
"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 andcomputer processing of x-ray transmission data.
"Contact therapy system" means an x-ray system used for therapy which is designed for veryshort treatment distances (5 centimeters or less), usually employing peak tube potentials in therangeof20to50kVp.
"Dead-man switch" means a switch constructed so that a circuit-closing contact can bemaintained 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 simpleor complex, which serves some specific purpose or performs some other function.
"Industrial radiography" means the process used to perform the examination of the macroscopicstructure of materials by non-destructive methods using radioactive material or radiationmachines.
"Kilovolts peak (kVp)" means the crest value, in kilovolts, of the electric potential applied to thex-ray tube between the cathode and anode of a pulsating electric potential generator.
"Leakage radiation" means all radiation emanating from the diagnostic source assembly exceptfor 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 todetermine the presence, size, location and extent of cancerous or potentially cancerous tissue inthe breast.
"Radiation therapy simulation system" means a radiographic/fluoroscopic x-ray system usedexclusively for localizing the volume to be exposed during radiation therapy and confirming theposition and size of the therapeutic irradiation field.
"Radiological Physicist" means an individual who has the knowledge, training and experienceto measure ionizing radiation, evaluate safety techniques, advise regarding radiation protectionand quality assurance needs and apply the principles of radiological physics to diagnostic x-rayor 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 theSafety of Radiation Sources, April 1994.
[4] Illinois Department of Nuclear Safety Regulations 32 Illinois Administrative CodeChapter II Part 360 360-1 - 380-2 (1995).
[5] Radiation Protection and Safety GUIDES, 1995, GRPB-G1, Qualification andCertification of the Radiation Protection Personnel.
[6] Radiation Protection and Safety GUIDES, 1995, GRPB-G2, Notification andAuthorization 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.
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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
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