Sec.19-25d-9. Therapeutic x-ray installations

(a) Equipment

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

(2) Permanent diaphragms or cones used 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 obtained 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 one roentgen per hour at one meter, or, if the radiation from the slot is accessible to the patient, thirty roentgens per hour at five centimeters from the external opening.

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

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

(6) A timer shall be provided to terminate the exposure after a preset time regardless of what other exposure limiting devices are present.

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

(8) There shall be on the control panel an easily discernible indicator which will give positive information as to whether or not the x-ray tube is energized.

(b) Structural shielding

(1) All wall, floor and ceiling areas that can be struck by the useful beam, plus a border of one foot, shall be provided with primary protective barriers.

(2) All wall, floor and ceiling areas that, because of restrictions in the orientation of the useful beam, cannot be struck by the useful beam shall be provided with secondary barriers.

(3) With equipment operating above one hundred twenty-five kvp, the required barriers shall be an integral part of the building.

(4) With equipment operating above one hundred fifty kvp, the control station shall be within a protective booth or outside the treatment room.

(5) Interlocks shall be provided 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 two milliroentgens per hour and a maximum of ten milliroentgens per hour at a distance of one meter in any direction from the target. After such shut off or reduction in output, it shall be possible to restore the machine to full operation only from the control panel.

(6) Provision shall be made to permit continuous observation of patients during irradiation.

(7) Windows, mirror systems or closed-circuit television viewing screens used for observing the patient shall be so located that the operator may see the patient and the control panel from the same position.

(c) Operating procedures

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

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

(3) No individual who works with radiation, unless he is the patient, shall be in the treatment room during exposure. No other individual shall be there except when it is clinically necessary. If an individual is required to be in the treatment room with the patient during exposure, he shall be protected as much as possible from scattered radiation and shall not be in the useful beam.

(Effective October 1, 1982)