b. The gamma-beam apparatus must be calibrated by a qualified expert before
use for the treatment of patients.
c. The gamma-beam therapy installation should not be operated routinely until
the radiation safety has been established by a radiation protection survey. The
apparatus should be operated only in conformance with recommendations of the
survey. A resurvey should be performed each time the apparatus is loaded with a new
d. Emergency procedures to be followed in the event of failure of the beam
control mechanism should be established and posted at the control panel.
e. When a patient must be held in position for radiation therapy, mechanical
supporting or restraining devices should be used. If an individual must hold the patient,
that individual should be adequately protected and he should be positioned so that the
useful beam will not strike any part of his body. The exposure of any individual used for
this purpose should be monitored.
f. With the possible exception cited above, no person other than the patient
should be in the treatment room while the source is in the "ON" position.
g. Records required by Federal and other applicable authorities as well as
records consistent with the competent practice of radiation therapy must be maintained.
h. Leak test results should be kept on a consecutive entry log and the
removable activity should be recorded in microcuries.
i. Lead, lead ruber, or lead foil used for limiting the field should not transmit
more than 5 percent of the useful beam.
EXAMPLE OF EMERGENCY PROCEDURES FOR FAILURE OF GAMMA-
BEAM CONTROL MECHANISM
If the light signals indicate that the beam control mechanism has failed to
terminate the exposure at the end of the preset time (for example, if the red light stays
on and/or the green signal does not light up), the source may still be in the "ON"
position. The following steps are to be carried out in a calm manner.
a. For the radiation therapy technician:
Open the door to the treatment room.
If the patient is ambulatory, direct him to get off the table and leave the