Effective Date: 01/08/97
Title: Section 16.60 - Therapy equipment operated at potentials up to 10 million volts
16.60 Therapy equipment operated at potentials up to 10 million volts.(11)
(a) Equipment. (1) The protective tube housing shall be of therapeutic type.
(2) Fixed diaphragms or cones used to restrict the useful beam shall be so constructed as to provide the same degree of protection as is required of the tube housing.
(3) Adjustable or removable beam limiting diaphragms or cones shall not transmit more than five percent of the useful beam at the maximum kilovoltage and with the maximum treatment filter.
(4) The filter system shall be so arranged as to minimize the possibility of error in filter selection and alignment. The filter slot shall be so constructed that the radiation escaping through it does not produce an exposure exceeding one roentgen per hour at one meter, or if the patient is likely to be exposed to radiation escaping from the slot, 30 roentgens per hour at two inches (5 centimeters) from the external opening. Each removable filter shall be marked with its thickness and material.
(5) It shall be possible for the person operating the controls of the therapeutic equipment to determine from the operating position what filters are in place in the equipment. Filters shall be so mounted as to prevent their movement during the treatment.
(6) The X-ray tube shall be secured so that it cannot move in respect to the the housing aperture. A mark on the exterior of the tube housing is recommended to indicate the focal spot.
(7) Adequate devices shall be provided to secure the tube housing during stationary portal treatment.
(8) An easily discernible indicator which shows whether or not X-rays are being produced shall be on the control panel.
(9) A suitable exposure control device (e.g. an automatic timer, exposure meter or dose meter) shall be provided to terminate the exposure automatically after a preset time interval or preset exposure or dose limit. Means shall be provided for the operator to terminate the exposure at any tlme.
(10) Equipment utilizing shutters to control the useful beam shall have a shutter position indicator on the control panel.
(b) Structural shielding. (1) The protective barriers for all therapy equipment operating at voltages above 60 kvp shall be fixed to the wall of the building.
(2) The control panel for all therapy equipment operating at voltages above 150 kVp installed after January 1, 1963, shall be located outside the treatment room.
(c) Conditions for operation of equipment. (1) The output of the X-ray generator shall be calibrated prior to the use of the apparatus for treating humans. Calibration shall be performed by a person qualified pursuant to subdivision (f) of section 16.122 of this Part. The method of calibration used shall be in accordance with procedures recommended by the American Association of Physicists in Medicine for the energy and type of radiation employed. Calibration shall be made at least annually. Recalibration, however, shall be made after each tube replacement and after any changes or replacements in the generating apparatus, or changes or updates in computer programs which govern or interact with the functions of the machine and which could change the X-ray output.
(2) No person other than the patient, shall be permitted to remain within the X-ray therapy room while the X-ray generator is in operation.
(3) Every entrance to an X-ray therapy room in which equipment is capable of operating above 150 kV shall be protected by interlocks to insure that during the production of X-rays no person can enter the therapy room without turning off the radiation equipment. They shall be so arranged that irradiation equipment cannot be started again without manually resetting the controls.
(4) Windows, mirror systems, or closed-circuit television viewing screens 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.
(5) Provision shall be made for oral communication with the patient.
(6) In addition to the interlocking controls, there shall be installed signals which are readily observable or discernible near the outside of all access doors to indicate the production of X-rays.
_________________________________________________________________________ FOOTNOTE (11): See section 16.61 for special requirements for equipment operating below 60 kVp. _________________________________________________________________________