New Jersey Administrative Code
Title 7 - ENVIRONMENTAL PROTECTION
Chapter 28 - RADIATION PROTECTION PROGRAMS
Subchapter 14 - THERAPEUTIC INSTALLATIONS
Section 7:28-14.4 - Therapeutic x-ray and therapeutic accelerator installations with energies of one MeV and above
Universal Citation: NJ Admin Code 7:28-14.4
Current through Register Vol. 56, No. 6, March 18, 2024
(a) The following are the equipment requirements related to leakage radiation to the patient area:
1. Leakage radiation shall be measured under conditions producing maximum leakage radiation and shall be reported as absorbed dose in rads or grays in water. For equipment installed on or after October 1, 1987, measurements shall include x-rays, electrons and neutrons. For equipment incapable of operating at energies greater than 10 MeV, measurements shall exclude neutrons. For equipment installed before October 1, 1987, measurements shall exclude neutrons. The leakage radiation shall be measured in a plane perpendicular to the central axis of the beam located at the normal treatment distance or passing through the isocenter. The leakage radiation at any point on this plane outside the useful beam but within two meters of the central axis of the beam shall not exceed 0.1 percent of the maximum radiation of the useful beam, measured at the point of intersection of the central axis and the plane;
2. Measurements for leakage radiation shall be averaged over an area up to, but not exceeding, 100 square centimeters at the positions specified. For equipment installed on or after October 1, 1987, measurements of the portion of the leakage radiation dose contributed by neutrons shall be averaged over an area up to, but not exceeding, 400 square centimeters. For equipment incapable of operating at energies greater than 10 MeV, measurements shall exclude neutrons. For equipment installed before October 1, 1987, measurements shall exclude neutrons;
3. For each system the registrant shall determine, or obtain from the manufacturer, the amount of leakage radiation at the positions specified in 1 above. Records of leakage radiation shall be maintained at the facility for inspection by the Department.
(b) The following are the equipment requirements for leakage radiation outside the patient area:
1. Except in the area specified in (a) above as the patient area, the x-ray leakage measured as absorbed dose in rads or grays in water, at any location averaged over 100 square centimeters one meter from the path of the charged particles before they strike the target or the window, shall not exceed 0.1 percent of the maximum absorbed dose in the circular plane specified in (a) above;
2. Except in the area specified in (a) above as the patient area, neutron leakage measured as absorbed dose in rads or grays in water, at any point one meter from the path of the charged particles before they strike the target or the window, shall not exceed 0.05 percent of the maximum absorbed dose in the circular plane specified in (a) above;
3. The registrant shall determine, or obtain from the manufacturer, the actual leakage radiation existing at the positions specified in 1 and 2 above for specified operating conditions. Radiation measurements excluding neutrons shall be averaged over an area up to, but not exceeding, 100 square centimeters at the positions specified. For equipment installed on or after October 1, 1987, neutron measurement shall be averaged over an area up to, but not exceeding, 400 square centimeters. For equipment incapable of operating at energies greater than 10 MeV, measurements shall include neutrons. For equipment installed prior to October 1, 1987, measurement of neutrons shall be excluded.
(c) The following are the equipment requirements for beam limiting devices;
1. For equipment installed on or after October 1, 1987, adjustable or interchangeable beam limiting devices shall be provided and such devices shall transmit no more than one percent of the useful beam at the normal treatment distance for the portion of the useful beam which is to be attenuated by the beam limiting device. The neutron component of the useful beam shall not be included in this requirement; and
2. For equipment installed prior to October 1, 1987, the beam limiting device shall meet the requirements of (a)1 above except that such device shall transmit no more than two percent of the useful beam.
(d) The following are the equipment requirements for filters:
1. If the absorbed dose rate information required by (p) below relates exclusively to operation with a field flattening or beam scattering filter in place, such filter shall be removable only by the use of tools;
2. In systems installed on or after October 1, 1987, which utilize a system of wedge filters, interchangeable field flattening filters or interchangeable beam scattering filters:
i. Irradiation shall not be possible until a selection of a filter has been made at the treatment control panel;
ii. An interlock system shall be provided to prevent irradiation if the filter selected is not in the correct position;
iii. A display shall be provided at the treatment control panel showing the filter in use;
iv. Each filter which is removable from the system without the use of tools shall be clearly marked with an identification number and accompanying documents shall contain a corresponding drawing or other description of the filter, showing dimensions and materials. The identification number shall appear on the wedge filter as well as on its tray. The identification number shall be referable to wedge angle and wedge factor; and
v. An interlock shall be provided to prevent irradiation if any filter selection operation carried out in the treatment room does not agree with the filter selection operation carried out at the treatment control panel.
3. The only filter requirement for equipment installed prior to October 1, 1987 shall be that required by (d)2iv above.
(e) Beam quality data sufficient to assure that the following beam quality requirements are met shall be determined or obtained from the manufacturer by the registrant:
1. For radiotherapy systems capable of electron beam therapy the absorbed dose in water resulting from x-rays in a useful electron beam shall be determined at a point on the central axis of the beam 10 centimeters greater than the practical range of the electrons. This shall not exceed the values stated in the following table. Linear interpolation shall be used for values not stated;
TABLE
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2. Compliance with 1 above shall be determined using:
i. A measurement within a phantom with the incident surface of the phantom at the normal treatment distance and normal to the central axis of the beam;
ii. The largest field size available which does not exceed 15 centimeters by 15 centimeters; and
iii. A phantom whose cross-sectional dimensions exceed the measurement radiation field by at least five centimeters and whose depth is sufficient to perform the required measurement.
3. The absorbed dose at a surface located at the normal treatment distance, at the point of intersection of that surface with the central axis of the useful beam during x-ray irradiation, shall be measured at intervals not to exceed 12 months and the results of such measurements shall be maintained with the records of calibration;
4. The measurements required by (e)3 above shall conform to the following requirements:
i. Measurements shall be made within a phantom using an instrument which will allow extrapolation to the surface absorbed dose;
ii. Measurements shall be made using a phantom whose size and placement meet the requirements of 2iii above;
iii. Measurements shall be made after removal of all beam modifying devices which can be removed without the use of tools, except for beam scattering or beam flattening filters; and
iv. Measurements shall be made over the range of field sizes clinically used.
5. The registrant shall determine, or obtain from the manufacturer, the maximum percentage absorbed dose due to stray neutrons in the useful beam for specified operating conditions.
(f) All therapy systems shall be provided with radiation detectors in the radiation head.
1. Equipment installed on or after October 1, 1987 shall be provided with at least two radiation detectors. The detectors shall be incorporated into two monitoring systems arranged either as a primary/primary combination or as a primary/secondary combination;
2. Equipment installed prior to October 1, 1987 shall be provided with at least one radiation detector. This detector shall be incorporated into a primary system. Failure of this detector shall automatically cause the beam to be terminated; and
3. Each detector and system into which the detector is incorporated shall meet the following requirements:
i. Each detector shall be removable only with tools and shall be interlocked to prevent incorrect positioning;
ii. Each detector shall be capable of independently monitoring and controlling the useful beam;
iii. Each detector shall form part of a dose monitoring system from whose readings in dose monitor units the absorbed dose at a reference point in the treatment volume can be calculated;
iv. For equipment installed on or after October 1, 1987, the primary dose monitoring system shall have a full beam transmission detector which is placed on the patient side of any fixed added filters other than a wedge filter;
v. For equipment installed on or after October 1, 1987, the design of the dose monitoring system of (f)3iii above shall assure that:
(1) The malfunctioning of one system shall not affect the correct functioning of the second system; and
(2) The failure of any element which may be common to both systems shall terminate the useful beam.
vi. Each dose monitoring system shall have a legible display at the treatment control panel. Each display shall:
(1) Maintain a reading until intentionally reset to zero;
(2) Utilize a design such that increasing dose is displayed by increasing numbers and shall be so designed that, in the event of an overdosage of radiation, the absorbed dose may be accurately determined under all normal conditions of use or foreseeable failures; and
(3) In equipment installed on or after October 1, 1987 have only one scale and no scale multiplying factors when employed for routine therapy. A scale multiplying factor may be applied to the regularly used accumulated dose indicator when used in conjunction with special treatment modes which use higher than normal dose rates and require specially safeguarded operating procedures to initiate.
vii. In the event of power failure, the dose monitoring information required in 3vi above displayed at the control panel at the time of failure shall be retrievable in at least one system.
(g) Beam symmetry requirements are the following:
1. For equipment installed on or after October 1, 1987 and which is inherently capable of producing useful beams with asymmetry exceeding five percent, at least four different parts of the radiation beam shall be monitored before the beam passes through the beam limiting device. If the difference in dose rates between any two of these different parts exceeds five percent an indication of this condition is to be made at the control panel and the irradiation shall automatically terminate; and
2. The beam symmetry requirements of 1 above shall be met if the user can demonstrate to the satisfaction of the Department that adequate fail-safe protection against the beam asymmetry is incorporated into the inherent design of the accelerator.
(h) Equipment requirements for the selection and display of dose monitor units are the following:
1. Irradiation shall not be possible until a selection of a number of dose monitor units has been made at the treatment control panel;
2. The pre-selected number of dose monitor units shall be displayed at the treatment control panel until reset manually for the next irradiation; and
3. After termination of irradiation, it shall be necessary to manually cycle the pre-selected dose monitor units through zero or manually change at least one digit on the dose monitor units selector before treatment can be initiated.
(i) Equipment requirements for termination of irradiation by the dose monitoring system are the following:
1. Each of the required monitoring systems shall be capable of terminating irradiation independently;
2. Each primary dose monitoring system shall terminate irradiation when the pre-selected number of dose monitor units has been detected by the system;
3. Each secondary dose monitoring system shall terminate irradiation when 10 percent or 30 monitor units above the pre-selected number of dose monitor units has been detected by the system;
4. For equipment installed on or after October 1, 1987, the indicator on the control panel shall show which monitoring system has terminated the beam.
(j) Interruption switches shall be provided which make it possible to interrupt irradiation and equipment movements at any time from the operator's position at the treatment control panel. Following an interruption, it shall be possible to restart irradiation by operator action without any reselection of operating conditions. If any change is made of a pre-selected value during an interruption the equipment shall go to termination condition.
(k) Termination switches shall be provided at the operator's position at the treatment control panel, which make it possible to terminate irradiation and equipment movements, or to go from an interruption condition to termination condition.
(l) The following are the equipment requirements for timer systems:
1. A timer system shall be provided which has a display at the treatment control panel. It shall be graduated in minutes and seconds and/or fractions of minutes. It shall have a pre-set time selector and an elapsed time indicator;
2. The timer shall terminate irradiation when a pre-selected time has elapsed if the dose monitoring systems fail to do so;
3. The timer shall not permit an exposure if set at zero;
4. There shall be an elapsed-time indicator which is activated when radiation is emitted and which retains its reading after irradiation is interrupted or terminated; and
5. After termination of irradiation on delivery of the present dose, it shall be necessary to manually change at least one digit on the pre-set time control before treatment can be re-initiated.
(m) Equipment capable of both x-ray therapy and electron therapy shall have the following equipment requirements for selection of radiation type:
1. Irradiation shall not be possible until a selection of radiation type has been made at the treatment control panel;
2. An interlock system shall be provided to insure that the equipment can emit only the radiation type which has been selected, except as noted in 4 below;
3. An interlock system shall be provided to prevent irradiation if any operations selected in the treatment room do not agree with the operations selected at the treatment control panel;
4. An interlock system shall be provided to prevent irradiation with x-rays when electron applicators are fitted except to obtain a port film and to prevent irradiation with electrons when accessories specific for x-ray therapy are fitted; and
5. The radiation type selected shall be displayed at the treatment control panel before and during irradiation.
(n) The following are the equipment requirements for the selection of energy for equipment capable of generating radiation beams of different energies:
1. Irradiation shall not be possible until a selection of energy has been made at the treatment control panel;
2. An interlock system shall be provided to prevent irradiation if any selected operations carried out in the treatment room do not agree with the selected operations carried out at the treatment control panel;
3. The nominal energy selected shall be displayed at the treatment control panel before and during irradiation; and
4. For equipment installed on or after October 1, 1987, an interlock system shall be provided to terminate irradiation if the energy of the electrons striking the x-ray target or electron window deviates by more than plus or minus five percent or plus or minus 2 MeV, whichever is smaller, from the selected nominal energy.
(o) The following are the equipment requirements for selection of mode of therapy for equipment capable of both stationary beam therapy and moving beam therapy:
1. Irradiation shall not be possible until a selection of stationary beam therapy or moving beam therapy has been made at the treatment control panel;
2. An interlock system shall be provided to insure that the equipment can operate only in the mode which has been selected;
3. An interlock system shall be provided to prevent irradiation if any selected operations carried out in the treatment room do not agree with the selected operations carried out at the treatment control panel;
4. An interlock system shall be provided to interrupt irradiation if the movement stops during moving beam therapy;
5. Moving beam therapy shall be so controlled that the required relationship between the number of dose monitor units and movement is obtained; and
6. The mode of operation shall be displayed at the treatment control panel.
(p) Equipment installed on or after October 1, 1987, shall be provided with a system from whose readings the absorbed dose rate at a reference point in the treatment volume can be calculated. The radiation detectors specified in (f) above may form part of this system. In addition, the quotient of the number of dose monitor units by time shall be displayed at the treatment control panel.
(q) The registrant shall determine, or obtain from the manufacturer, the location of the following with reference to an accessible point on the radiation head and under all possible orientations of the useful beam:
1. The x-ray target or the virtual source of x-rays; and
2. The electron window, the scattering foil, or the virtual source of electrons.
(r) When pre-selection of any of the operating conditions requires action in the treatment room and at the treatment control panel, selection at one location shall not give a display at the other location until the requisite selected operations in both locations have been completed.
(s) Shadow trays shall be designed to minimize patient entrance skin dose consistent with achieving their primary purpose of safely supporting beam-modifying accessories while transmitting the light field.
(t) The following are the facility and shielding requirements for therapeutic x-ray and therapeutic accelerator installations with energies of one MeV and above:
1. The systems shall have shielding adequate to meet the requirements of N.J.A.C. 7:28-5 and 6;
2. Except for entrance doors or beam interceptors, all the required barriers shall be fixed barriers;
3. The treatment control panel shall be located outside the treatment room;
4. Windows, mirrors, closed-circuit television, or other equivalent viewing systems shall be provided to permit continuous observation of the patient during irradiation and shall be so located that the operator may observe the patient from the treatment control panel. When the primary viewing system is by electronic means (for example, television), a secondary viewing system shall be provided for use in the event of failure of the primary system;
5. Provision shall be made for two-way aural communication between the patient and the operator at the treatment control panel;
6. Treatment room entrances shall be provided with warning lights in readily observable positions near the outside of all access doors which will indicate when the useful beam is "on";
7. Interlocks shall be provided such that all entrance doors shall be closed before treatment can be initiated or continued. If the radiation beam is interrupted by any door opening, it shall only be possible to restore the machine to operation by closing the door and reinitiating exposure by manual action at the control panel; and
8. At least one "Panic" emergency shut-off button shall be located in the treatment room and one by the control panel. The "Panic" button shall be clearly visible, easily accessible and be capable of immediately terminating machine operation.
(u) The following are the calibration requirements for therapeutic x-ray and therapeutic accelerator installations with energies of one MeV and above:
1. The calibration of systems shall be performed before the system is first used for irradiation of a patient, and thereafter at time intervals which do not exceed 12 months and after any change which might, in the opinion of the qualified radiological physicist, significantly alter the calibration, spatial distribution, or other characteristics of the therapy beam;
2. The calibration shall be performed with an established calibration protocol which meets or exceeds the requirements set by the American Association of Physicists in Medicine;
3. The calibration shall be performed by a qualified radiological physicist;
4. The calibration shall be performed with a dosimetry system whose calibration shall be directly traceable to a national standard and which shall have been calibrated within the preceding three years;
5. The calibration shall be such that the dose at a reference point in soft tissue may be calculated within plus or minus 5 percent;
6. The full calibration of the therapy beam shall include, but not be limited to, the following determinations:
i. Verification that the equipment is operating in compliance with the design specifications for accuracy of the light localizer, the side light and backpointer alignment with the isocenter;
ii. Verification that the equipment is operating in compliance with the design specifications for acceptable variation in the axis of rotation for the table, gantry and jaw system, and beam flatness and symmetry at specified depths;
iii. The absorbed dose rate at representative depths in a phantom for the range of field sizes used for each effective energy, and for representative distances used for radiation therapy;
iv. The congruence between the radiation field and the field indicated by the localizing device;
v. The uniformity of the radiation field and its dependency upon the direction of the useful beam;
vi. Verification of depth-dose data and isodose curves applicable to the specific machine; and
vii. Verification of the applicability and transmission factors of all accessories such as wedges, shadow trays, compensators, etc.
7. Records of the calibration performed pursuant to 1 above shall be maintained by the registrant and made available for inspection by the Department for five years after completion of the calibration; and
8. A copy of the latest full calibration shall be available for calculating patient treatment parameters.
(v) Spot checks meeting the following requirements shall be performed on all therapeutic x-ray and therapeutic accelerator installations with energies of one MeV and above:
1. The qualified radiological physicist will determine those parameters to be spot-checked and the procedure to be used when performing those spot checks. The spot-check procedure shall be in writing and shall specify the frequency at which tests or measurements are to be performed, not to exceed one month, and the acceptable tolerance for each parameter measured in the spot-check. A qualified radiological physicist need not actually perform the spot-check measurement. If a qualified radiological physicist does not perform the spot-check measurement, the results of the spot-check measurement shall be reviewed by a qualified radiological physicist within 15 days;
2. The measurements taken during spot-checks shall demonstrate the degree of consistency of the operating characteristics which can affect the radiation output of the system or the radiation delivered to a patient during a therapy procedure;
3. The cause for a parameter exceeding tolerances set by the qualified radiological physicist shall be promptly investigated and corrected before the system is used for patient irradiation;
4. Whenever a spot-check indicates a significant change in the operating characteristics of a system, as specified in the spot-check procedures, the system shall be recalibrated as required in (u) above; and
5. Records of spot-check measurements performed shall be maintained by the registrant for a period of five years and made available for inspection by the Department.
(w) Operating procedures for therapeutic x-ray and therapeutic accelerator installations with energies of one MeV and above are as follows:
1. Therapeutic systems shall not be left unattended unless the system is secured against unauthorized use;
2. No individual other than the patient shall be in the treatment room during treatment of a patient;
3. If a patient must be held in position during treatment, mechanical supporting or restraining devices shall be used; and
4. The system shall not be used in the administration of radiation therapy unless the requirements of (u) and (v) above have been met.
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