N.J. Admin. Code § 7:28-14.3

Current through Register Vol. 56, No. 21, November 4, 2024

Section 7:28-14.3 - Therapeutic x-ray systems with energies less than one MeV

(a) Equipment requirements for therapeutic x-ray systems with energies less than one MeV are as follows:

1. Leakage radiation shall be measured under conditions which provide maximum leakage radiation. The leakage radiation shall not exceed the value specified at the distance specified for the classification of that x-ray system. Compliance shall be determined by measurements averaged over an area of 100 square centimeters. Measurement shall be performed at installation and whenever the tube is changed. Measurement shall be performed at least once every five years;

i. For Contact Therapy Systems, leakage radiation shall not exceed 100 milliroentgens in one hour at five centimeters from the surface of the tube housing assembly;

ii. For 0-150 kVp Systems which are installed prior to October 1, 1987, leakage radiation shall not exceed one roentgen in one hour at one meter from the target;

iii. For 0-150 kVp Systems which are installed on or after October 1, 1987, leakage radiation shall not exceed 100 milliroentgens in one hour at one meter from the target;

iv. For 151 to 500 kVp Systems the leakage radiation shall not exceed one roentgen in one hour at one meter from the target;

v. For 501 to 999 kVp Systems the leakage radiation shall not exceed 0.1 percent of the useful beam exposure rate at one meter from the target; and

vi. Records of leakage radiation shall be maintained at the facility for at least five years and shall be made available for inspection by the Department.

2. Beam limiting devices for equipment installed on or after October 1, 1987 shall transmit no more than one percent of the useful beam, for the portion of the beam which is to be attenuated by the beam limiting device, when the equipment is operating at maximum kVp and with maximum filtration. Measurements shall be made at a distance of one meter from the beam limiting device and in a plane perpendicular to the central axis of the beam. For equipment installed before October 1, 1987, transmissions shall not exceed five percent of the useful beam;

3. The filter system shall be so designed that:

i. It will minimize the possibility of error in filter selection;

ii. Filters cannot be accidentally displaced from the useful beam at any possible tube orientation;

iii. Each filter is marked as to its material of construction and its thickness or wedge angle for wedge filters;

iv. It shall be possible for the operator to determine the presence or absence of any filter in the useful beam when the operator is at the control panel, either by display at the control panel or by direct observation;

v. For equipment installed prior to October 1, 1987, the radiation at five centimeters from the filter insertion slot opening does not exceed 30 roentgens per hour under any operating conditions; and

vi. For equipment listed on or after October 1, 1987, the radiation from the filter slot shall not exceed the leakage radiation specified in (a)1 above.

4. A means shall be provided to immobilize the tube housing assembly during stationary treatments;

5. The tube housing assembly shall be so marked that it is possible to determine the location of the focal spot to within five millimeters, and such marking shall be readily accessible for use during calibration procedures;

6. Equipment employing Beryllium or other low-filtration windows shall have a removable shield of at least 0.5 millimeter lead equivalency at 100 kVp that can be positioned over the entire useful beam exit port during periods when the beam is not in use;

7. Radiotherapy systems of greater than 150 kVp installed on or after October 1, 1987 shall be provided with a beam monitor system which shall:

i. Include a radiation detector which is placed on the patient side of any fixed added filters other than a wedge filter;

ii. Have the radiation detector interlocked to prevent its incorrect positioning in the useful beam;

iii. Not allow irradiation until a pre-selected value of exposure or pre-selected number of dose monitor units has been made at the treatment control panel;

iv. Independently terminate irradiation when the pre-selected value of exposure or dose monitor units has been reached;

v. Be so designed that, in the event of a system malfunction or electrical power failure, the dose administered to a patient prior to the system malfunction or power failure can be accurately determined;

vi. Have a display at the control panel, reading in roentgens, or coulombs per kilogram from which the dose at a reference point in the treatment volume can be calculated;

(1) The reading shall be maintained in the display at the control panel until intentionally reset to zero; and

vii. Have a control panel display which does not have scale multiplying factors and utilizes a design such that an increasing dose is displayed by increasing numbers.

8. The following are the equipment requirements for timer systems:

i. 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. For equipment installed on or after October 1, 1987, it shall also have an elapsed time indicator;

ii. The timer shall terminate irradiation when a pre-selected time has elapsed;

iii. The timer shall permit pre-setting and determination of exposure times to an accuracy of one second or less;

iv. The timer shall not permit an exposure if set at zero;

v. When patient irradiation is controlled by a shutter mechanism the timer shall not begin to run until the shutter is opened;

vi. Equipment installed on or after October 1, 1987 shall have an elapsed-time indicator which is activated when radiation is emitted and retains its reading after irradiation is interrupted or terminated; and

vii. After irradiation is terminated and before irradiation can be reinitiated, it shall be necessary to cycle the pre-set time selector through zero time.

9. In addition to the control panel displays required in other provisions of this subsection, the control panel shall have:

i. An indication of whether electrical power is available at the control panel and if activation of the x-ray tube is possible;

ii. An indication of whether x-rays are being produced;

iii. Means for indicating kVp and x-ray tube current; and

iv. The means for terminating an exposure at any time.

10. There shall be a means of determining the source-to-patient distance to within 10 percent or one centimeter, whichever is smaller; and

11. Unless it is possible to bring the x-ray output to the prescribed exposure parameters within five seconds, the entire useful beam shall be attenuated automatically by a shutter having a lead equivalency not less than that of the tube housing assembly. In addition:

i. After the unit is at operating parameters, the shutter shall be controlled electrically from the control panel by the operator; and

ii. An indication of shutter position shall appear at the control panel.

(b) In addition to shielding adequate to meet the requirements of N.J.A.C. 7:28-5 and 6, the treatment room design and shielding requirements for systems capable of operating above 50 kVp, shall be the following:

1. There shall be warning lights in treatment rooms to which access is possible through more than one entrance. The warning lights shall be placed in readily observable positions near the outside of all access doors and shall indicate when the useful beam is "on";

2. There shall be means for two-way aural communication between the patient and the operator at the control panel at all times when the system is in operation;

3. A window, mirror, closed-circuit television, or an equivalent system shall be provided to permit continuous observation of the patient during irradiation and shall be so located that the operator can observe the patient from the control panel. When the primary viewing system is by electronic means (for example, television), a secondary viewing system shall be available for use in the event of failure of the primary viewing system;

4. Treatment rooms which contain an x-ray system capable of operating above 150 kVp shall meet the following additional requirements:

i. All required shielding, except for any beam interceptor, shall be provided by fixed barriers;

ii. The control panel shall be outside the treatment room;

iii. All entrance doors of the treatment room shall be electrically connected to the control panel in such a way that x-ray production cannot occur unless all doors are closed;

iv. When any entrance door of the treatment room is opened while the x-ray tube is activated, x-ray production shall terminate within one second; and

v. After the radiation output of the x-ray tube has been terminated by the opening of any door of the treatment room, it shall be possible to restore the x-ray system to full operation only upon closing the door, and subsequently, reinitiating the exposure at the control panel.

(c) The following are the calibration requirements for therapeutic x-ray systems with energies less than one MeV:

1. System calibrations 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 significantly alter the calibration or other characteristic of the therapy beam;

2. The calibration of the radiation output of the x-ray system shall be performed by a qualified radiological physicist;

3. Calibration of the radiation output of an x-ray system shall be performed with an instrument whose calibration shall be directly traceable to a national standard and which shall have been calibrated within the preceding three years;

4. The calibration shall be such that the dose at a reference point in soft tissue can be calculated to within +/- 5 percent;

5. The calibration of the x-ray system shall include, but not be limited to, the following determinations;

i. Verification that the x-ray system is operating in compliance with the radiological design specifications;

ii. The exposure rates for each combination of field size, technique factors, filter, and treatment distance used;

iii. The congruence between the radiation field and the field indicated by the localizing device if such device is present; and

iv. The uniformity of the radiation field symmetry for representative field sizes used.

6. Records of 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.

(d) Spot checks shall be performed on therapeutic x-ray systems with energies greater than 0.018 MeV and less than one MeV and shall meet the following requirements:

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 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. 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;

4. 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; and

5. Records of spot-check measurements shall be maintained by the registrant and made available for inspection by the Department for a period of five years following such measurement.

(e) The following procedures shall be followed when operating therapeutic x-ray systems with energies less than one MeV:

1. A therapeutic x-ray system 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 unless such individual is protected by a barrier meeting the requirements of N.J.A.C. 7:28-6. No individual other than the patient shall be in the treatment room during exposure when the kVp exceeds 50;

3. When a patient must be held in position for radiation therapy, mechanical supporting or restraining devices shall be used; and

4. Except for contact therapy devices, the tube housing assembly shall not be held by an individual during exposure.

(f) The x-ray system shall not be used in the administration of radiation therapy unless the requirements of this section have been met.

N.J. Admin. Code § 7:28-14.3

Correction: Therapeutic x-ray systems with energies less than one MeV for 0-150 kVp systems which are installed prior to October instead of January.
See: 19 N.J.R. 1917(c).
Amended by R.2005 d.239, effective 7/18/2005.
See: 37 N.J.R. 8(a), 37 N.J.R. 2675(b).
In (a)1v, deleted "at a distance of one meter from the target" following "the leakage radiation".