NAC459.598. X-ray and electron therapy installations: Filters; beam monitors.

     1. In equipment which uses a system of wedge filters, interchangeable field flattening filters or beam scattering filters:

     (a) Irradiation must not be possible until a selection of filter has been made at the treatment control panel;

     (b) An interlock system must be provided to prevent irradiation if the filter is not in the correct position; and

     (c) A display must be provided at the treatment control panel showing the filter, filters or zero filter in use.

     2. Existing equipment and new equipment manufactured or installed after February 28, 1980, must be provided with at least one radiation detector in the radiation head. This detector must be incorporated into a primary system. Each detector:

     (a) Must be capable of independently monitoring and controlling the useful beam; and

     (b) Must form part of a dose monitoring system from whose readings in dose monitor units the absorbed dose at a reference point in the treatment volume can be calculated.

     3. Each dose monitoring system must have a legible display at the treatment control panel which must:

     (a) Maintain a reading until intentionally reset;

     (b) In the event of power failure, have the capability of retrieving the information displayed at the time of failure; and

     (c) Be designed so that increasing doses are displayed by increasing numbers and in any over-dosage of radiation the absorbed dose may be accurately determined.

     [Bd. of Health, Radiation Control Reg. §§ 6.9.1.3-6.9.1.4.3.3, eff. 2-28-80]