N.M. Admin. Code § 20.3.6.607

Current through Register Vol. 35, No. 21, November 5, 2024

Section 20.3.6.607 - THERAPEUTIC X-RAY INSTALLATIONS

A. Equipment:

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

(2) Permanent diaphragms or cones for collimating the useful beam shall afford the same degree of protection as the tube housing. Adjustable or removable beam-defining diaphragms or cones shall transmit not more than five percent of the useful beam at the maximum kilovoltage and with maximum treatment filter.

(3) Filters shall be secured in place to prevent them from dropping out during treatment. The filter slot shall be so constructed that the radiation escaping through it does not exceed 1 R (0.258 mC/kg) per hour at 1 m (3.28 feet), or, if the radiation from the slot is accessible to the patient, 30 R (7.74 mC/kg) per hour at 5 cm (1.96 inches) from the external opening. Each removable filter shall be marked with its thickness and material.

(4) A filter indication system shall be used on all therapy machines using changeable filters. It shall be designed so as to permit easy recognition of any added filter in place. It shall indicate, from the control panel, the presence or absence of any filter.

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

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

(7) A device (e.g., an automatic timer exposure meter or dose meter) shall be provided to terminate the exposure after a preset time interval or preset exposure of dose limit. 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 panel.

(9) The control panel shall include a device (usually an ammeter) which will give positive indication of the production of x-rays whenever the x-ray tube is energized.

B. Structural Shielding:

(1) All walls, floors, and ceilings that can be struck by the useful beam shall be provided with primary barriers to the height of the ceiling. Low-voltage superficial therapy units only require a height of 2.1 m (6.88 feet).

(2) All walls, floors, and ceilings that, because of restrictions in the orientation of the useful beam, cannot be struck by the useful beam shall be provided with secondary barriers to a minimum height of 2.1 m (6.88 feet).

(3) With equipment operating at voltages above 50 kVp, the required barriers shall be an integral part of the building.

(4) With equipment operating above 150 kVp, the control panel shall be within a protective booth equipped with an interlocked door, or located outside the treatment room.

(5) Interlocks shall be provided for x-ray therapy equipment capable of operating above 150 kVp so that, when any door of the treatment room is opened, either the machine will shut off automatically or the radiation level within the room will be reduced to an average of not more than 2 mR (20 mSv) per hour and a maximum of 10 mR (100 mSv) per hour at a distance of 1 m (3.28 feet) in any direction from the target. After such shutoff or reduction in output, it shall be possible to restore the machine to full operation only from the control panel.

(6) Windows, mirror systems, or closed-circuit television viewing screen shall be provided to permit continuous observation of the patient during irradiation and shall be so located that the operator may see the patient and the control panel from the same position.

(7) Provision shall be made for oral communication with the patient from the control room.

(8) Treatment rooms to which access is possible through more than one entrance shall be provided with flashing warning lights in a readily observable position near the outside of all access doors, which will indicate when the useful beam is "on".

C. Operating Procedure:

(1) All new facilities, and existing facilities not previously surveyed, shall have a protection survey made by, or under the direction of a qualified expert. This also shall be done after any change in the facility which might produce a radiation hazard. The expert shall report his findings in writing to the person in charge of the facility and a copy of this report shall be transmitted to the Department.

(2) The facility shall be operated in compliance with any limitations indicated by the protection survey.

(3) When a patient must be held in position for radiation therapy, mechanical supporting or restraining devices shall be used whenever feasible, If the patient must be held by an individual, that individual shall be adequately protected and shall be positioned so that no part of the body will be struck by the useful beam and that the body is as far as possible from the edge of the useful beam. The exposure of any individual used for this purpose shall be monitored.

(4) The output of each therapeutic x-ray machine shall be calibrated by, or under the direction of, a qualified expert. The calibration shall be repeated after any change in or replacement of components of the x-ray generating equipment which could cause a change in x-ray output. Check calibrations shall be made at least once a year thereafter. Records of calibration shall be maintained by the registrant.

N.M. Admin. Code § 20.3.6.607

5-3-95; 20.3.6.607 NMAC - Rn, 20 NMAC 3.1.6.607, Recompiled xx/xx/xx