Subpart 1.
Spot checks required.
A licensee authorized to use gamma stereotactic radiosurgery
units for medical use must perform spot checks of each gamma stereotactic
radiosurgery facility and on each unit:
A. monthly;
B. before the first use of the unit on a
given day; and
C. after each source
installation.
Subp. 2.
Written procedures; review.
A licensee must:
A.
perform the spot checks required under subpart 1 according to written
procedures established by the authorized medical physicist. The authorized
medical physicist need not actually perform the spot check measurements;
and
B. have the authorized medical
physicist review the results of each spot check within 15 days. The authorized
medical physicist must notify the licensee as soon as possible in writing of
the results of each spot check.
Subp.
3.
Monthly requirements.
To satisfy subpart 1, item A, monthly spot checks must, at a
minimum:
A. ensure proper operation
of:
(1) the treatment table retraction
mechanism, using backup battery power or hydraulic backups with the unit
off;
(2) helmet
microswitches;
(3) emergency timing
circuits; and
(4) stereotactic
frames and localizing devices (trunnions); and
B. determine:
(1) the output for one typical set of
operating conditions measured with the dosimetry system described under part
4731.4468, subpart 2;
(2) the
difference between the measurement made in subitem (1) and the anticipated
output, expressed as a percentage of the anticipated output, that is, the value
obtained at last full calibration corrected mathematically for physical
decay;
(3) source output against
computer calculation;
(4) timer
accuracy and linearity over the range of use;
(5) on-off error; and
(6) trunnion centricity.
Subp. 4.
Other
requirements.
To satisfy subpart 1, items B and C, spot checks must ensure
proper operation of:
A. electrical
interlocks at each gamma stereotactic radiosurgery room entrance;
B. source exposure indicator lights on the
gamma stereotactic radiosurgery unit, on the control console, and in the
facility;
C. viewing and intercom
systems;
D. timer
termination;
E. radiation monitors
used to indicate room exposures; and
F. emergency off buttons.
Subp. 5.
Repair.
A licensee must arrange for repair of any system identified
under subpart 3 that is not operating properly as soon as possible.
Subp. 6.
Malfunctions.
If the results of the checks required under subpart 4
indicate the malfunction of any system, a licensee must lock the control
console in the off position and not use the unit except as may be necessary to
repair, replace, or check the malfunctioning system.
Subp. 7.
Record retention.
A licensee must retain a record of each check required under
subparts 3 and 4 and a copy of the procedures required under subpart 2
according to part 4731.4521.
