Section 325.5471. DEQ Did not provide language. Equipment.

(1) The housing of teletherapy equipment shall be so constructed that, at 1 meter from the source, the maximum exposure rate does not exceed 10 milliroentgens per hour when the beam control mechanism is in the "off" position. The average exposure rate measured at a representative number of points about the housing, each 1 meter from the source, shall not exceed 2 milliroentgens per hour.

(2)    For teletherapy equipment manufactured after the effective date of these rules, the leakage radiation measured at one meter from the source when the beam control mechanism is in the "on" position shall not exceed 1 roentgen per hour or 0.1% of the useful beam exposure rate.

(3)    Adjustable or removable beam-defining diaphragms shall allow transmission of not more than 5% of the useful beam exposure rate.

(4)    The beam control mechanism shall be of a positive design capable of acting in any orientation of the housing for which it is designed to be used. In addition to an automatic closing device, the mechanism shall be designed so that it can be manually returned to the "off" position with a minimum risk of exposure.

(5)  The closing device shall be so designed as to return automatically to the "off" position in the event of any breakdown or interruption of the activating force and shall stay in the "off" position until activated from the control panel.

(6)    When any door to the treatment room is opened, the beam control mechanism shall automatically and rapidly restore the unit to the "off" position and cause it to remain there until the unit is reactivated from the control panel.

(7)    There shall be at the housing and at the control panel a visible warning device that plainly indicates whether the beam is on or off.

(8)   The equipment shall be provided with a locking device to prevent unauthorized use.

(9)   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. It shall be designed to preserve its cumulated response in the event of equipment failure during patient treatment. If a timer is used, it shall permit accurate resetting and determination of exposure times as short as 1 second. Means shall be provided for the operator to terminate the exposure at any time.

(10)      Provisions shall be made to permit continuous observation of patients during irradiation.

History: 1979 AC.