Cal. Code Regs. Tit. 17, § 30312 - Therapeutic X-Ray Installations

(a) The user shall ensure therapeutic X-ray equipment meets the following:

(1) The tube housing shall be of therapeutic type.

(2) For equipment installed on or before August 1, 1979, permanent diaphragms or cones used for collimating the useful beam shall afford the same degree of protection as the housing. Adjustable or removable beam-defining diaphragms or cones shall transmit not more than 5 percent of the useful beam obtained at the maximum kilovoltage and with maximum treatment filter.

(3) For equipment installed after August 1, 1979, permanent beam-defining devices or diaphragms shall afford the same degree of protection as the housing. Adjustable or interchangeable beam-defining devices shall transmit no more than 2 percent of the useful beam for the portion of the useful beam which is to be attenuated by the beam limiting device. Measurements shall be averaged over an area up to but not exceeding 100 square centimeters at the normal treatment distance.

(4) Filters shall be secured in place to prevent them from dropping out during treatment. A filter indication system shall be used on all therapy machines using interchangeable filters. It shall indicate, from the control panel, or from the control station, the presence or absence of any filter except compensating filters, and it shall be designed to permit easy identification of the filter in place. The filter slot shall be so constructed that the radiation escaping through it does not exceed 1 roentgen per hour at 1 meter, or, if the patient is likely to be exposed to radiation escaping from the slot, 30 roentgens per hour at 5 centimeters from the external opening. Each interchangeable filter shall be marked with its thickness and material.

(5) The X-ray tube shall be so mounted that it cannot turn or slide with respect to the aperture.

(6) Means shall be provided to immobilize the tube housing during stationary portal treatment.

(7) A suitable exposure control device such as an automatic timer, exposure meter, or dose meter shall be provided to terminate the exposure after a preset time interval or preset exposure or dose limit. A timer shall be provided to terminate the exposure after a preset time regardless of what other exposure limiting devices are present. Means shall be provided for the operator to terminate the exposure at any time.

(8) Equipment utilizing shutters to control the useful beam shall have a shutter position indicator on the control.

(9) An easily discernible indicator which shows whether or not X-rays are being produced shall be on the control panel.

(10) Mechanical and/or electrical stops shall be provided on X-ray machines capable of operating at 150 kVp or above to insure that the useful beam is oriented only toward primary barriers.

(11) When the relationship between the beam interceptor (when present) and the useful beam is not permanently fixed, mechanical or electrical stops shall be provided to insure that the beam is oriented only toward primary barriers.

(b) The user shall ensure the following:

(1) When a patient must be held in position for radiation therapy, patient immobolization devices shall be used.

(2) No patient other than the one being treated shall be in the treatment room during exposure.

(3) No person other than the patient shall be in the treatment room when the tube is operated at potentials exceeding 150 kVp. At operating potentials of 150 kVp or below, persons other than the patient and operator may be in the treatment room for good reason but only if they are adequately protected and their radiation exposure is appropriately monitored.

(4) A calibration of the output of each therapeutic X-ray system shall be performed before the system is first used for irradiation of a patient, and thereafter at intervals not to exceed 24 months. Therapeutic X-ray equipment shall not be used for any therapy treatments except at those combinations of effective energy, field size, and treatment distance for which the equipment has been calibrated. The calibration shall be performed by or under the direct supervision of a TCP. After any change which might significantly alter the output, spatial distribution, or other characteristics of the therapy beam, the parameters which might be affected shall be measured.

(A) For therapy systems operating at potentials above 500 kVp, the determinations included in the calibration shall be provided in sufficient detail so that the absorbed dose in tissue in the useful beam may be calculated to within 5 percent. The calibration shall include, but shall not be limited to, the following determinations:

1. Verification that the equipment is operating in compliance with the design specifications concerning the light localizer, the side light and back-pointer alignment with the isocenter when these specifications are known and applicable, variation in the axis of rotation for the table, gantry and jaw system, and beam flatness and symmetry at specified depths.

2. The relative dose at various depths in a tissue equivalent phantom for each effective energy and the ranges of field sizes and treatment distances used for radiation therapy.

3. The congruence between the radiation field and the field indicated by the localizing device.

4. The uniformity of the radiation field and its dependency upon the direction of the useful beam.

5. The absolute dose per unit time and dose per monitor setting.

(B) For therapy systems operating at potentials between 150 kVp and 500 kVp inclusive, the calibration shall include, but shall not be limited to, the following determinations:

1. The exposure rates and/or dose rates for each combination of field size, technique factors, filter, and treatment distance used.

2. The degree of congruence between the radiation field and the field indicated by the localizing device if such device is present.

3. An evaluation of the uniformity of the radiation field symmetry for the field sizes used, and any dependence upon tube housing assembly orientation.

(5) All new installations and existing installations not previously surveyed shall have a radiation protection survey performed by or under the supervision of a TSP or a TCP. If the survey shows that supplementary shielding is required, a resurvey shall be performed by or under the supervision of a TSP or a TCP after its installation. In addition, a resurvey shall be made after every change which might decrease radiation protection significantly. The surveyor shall report his findings in writing to the user. The report shall indicate whether or not the installation is in compliance with all applicable radiation protection requirements of this section. The user shall report the findings of the survey in writing to the Department within 15 days of his receipt of the survey report.

(6) The exposure rate or dose rate of the useful beam and the size and shape of the useful beam shall be known with reasonable certainty at all times during operation of the therapeutic X-ray systems for medical purposes.

(7) Spot checks shall be performed at least once each week for therapeutic X-ray systems operating at potentials above 500 kVp, and at least once each month for therapeutic X-ray systems operating at 500 kVp or below.

(A) 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.

(B) For systems in which the calibrating person believes beam quality can vary significantly, spot checks shall include beam quality checks.

(C) The spot check procedures shall be in writing and shall have been developed or approved by a TCP. The written spot check procedures shall specify when measurements and determinations indicate an inconsistency or potential change in radiation output. When more than the minimum frequency of spot checking is necessary, the spot check procedures shall specify the frequency at which spot checks are to be performed.

(D) When spot check results are erratic or inconsistent with calibration data, a TCP shall be consulted immediately and the cause of the inconsistency corrected before the system is used for patient irradiation.

(8) Calibration of the therapy beam shall be performed with a measurement instrument which has been calibrated within the preceding two years directly, or through no more than one exchange, at the National Institute of Standards and Technology, or facility determined acceptable by the Department. In addition, indirect spot checks or intercomparisons of measurement instruments with secondary standards shall be made at least each six months.

(9) Reports of each radiation safety survey spot check and calibration performed pursuant to this section shall be maintained at the facility for at least three years. A copy of the treatment data developed from the latest calibration shall be available for use by the operator at the treatment control station.

Notes

Cal. Code Regs. Tit. 17, § 30312

1. Renumbering and amendment filed 9-4-73 as an emergency; effective upon filing (Register 73, No. 36). Approved by State Building Standards Commission 11-30-73.
2. Certificate of Compliance filed 12-28-73 (Register 73, No. 52).
3. Amendment of subsection (c)(5) filed 12-12-75; effective thirtieth day thereafter (Register 75, No. 50).
4. Amendment filed 6-24-80; effective thirtieth day thereafter (Register 80, No. 26).
5. Amendment filed 6-18-87; operative 7-18-87 (Register 87, No. 28).
6. Change without regulatory effect amending subsection (b)(7)(C) and (b)(8) filed 11-1-91 pursuant to section 100, title 1, California Code of Regulations (Register 92, No. 5).
7. Amendment of subsections (a), (b)-(b)(1), (b)(4), (b)(5)-(7) and (b)(7)(C)-(D) and amendment of NOTE filed 5-13-2020; operative 10-1-2020 pursuant to Government Code section 11343.4(b)(2) (Register 2020, No. 20).

Note: Authority cited: Sections 114975, 115000 and 131200, Health and Safety Code. Reference: Sections 114965, 114970, 115000, 115060, 131050, 131051 and 131052, Health and Safety Code.

1. Renumbering and amendment filed 9-4-73 as an emergency; effective upon filing (Register 73, No. 36). Approved by State Building Standards Commission 11-30-73.
2. Certificate of Compliance filed 12-28-73 (Register 73, No. 52).
3. Amendment of subsection (c)(5) filed 12-12-75; effective thirtieth day thereafter (Register 75, No. 50).
4. Amendment filed 6-24-80; effective thirtieth day thereafter (Register 80, No. 26).
5. Amendment filed 6-18-87; operative 7-18-87 (Register 87, No. 28).
6. Change without regulatory effect amending subsection (b)(7)(C) and (b)(8) filed 11-1-91 pursuant to section 100, title 1, California Code of Regulations (Register 92, No. 5).
7. Amendment of subsections (a), (b)-(b)(1), (b)(4), (b)(5)-(7) and (b)(7)(C)-(D) and amendment of Note filed 5-13-2020; operative 10/1/2020 pursuant to Government Code section 11343.4(b)(2) (Register 2020, No. 20).