Section 120.581 - Periodic Spot-checks for Gamma Stereotactic Radiosurgery Units(A) A licensee authorized to use a gamma stereotactic radiosurgery unit for medical use shall perform spot-checks on each gamma stereotactic radiosurgery facility and on each unit: (2) At the beginning of each day of use; and(3) After each source installation.(B) A licensee shall have the authorized medical physicist: (1) Establish written procedures for performing the spot-checks required in 105 CMR 120.581(A); and(2) Review the results of each spot-check required by 105 CMR 120.581(A)(1) within 15 days of the check. The authorized medical physicist need not actually perform the spot-check measurements. The authorized medical physicist shall notify the licensee as soon as possible, in writing, of the results of the spot check.(C) To satisfy the requirement of 105 CMR 120.581(A)(1), spot-checks must, at a minimum: (1) Assure proper operation of: (a) Treatment table retraction mechanism, using backup battery power or hydraulic backups with the unit off;(c) Emergency timing circuits; and(d) Stereotactic frames and localizing devices (trunnions).(2) Determine: (a) The output for one typical set of operating conditions measured with the dosimetry system described in 105 CmR 120.575(B);(b) The difference between the measurement made in 105 CMR 120.581(C)(2)(a) and the anticipated output, expressed as a percentage of the anticipated output (i.e., the value obtained at last full calibration corrected mathematically for physical decay);(c) Source output against computer calculation;(d) Timer accuracy and linearity over the range of use;(D) To satisfy the requirements of 105 CMR 120.581(A)(2) and (3), spot-checks must assure proper operation of: (1) Electrical interlocks at each gamma stereotactic radiosurgery room entrance(2) Source exposure indicator lights on the gamma stereotactic radiosurgery unit, on the control console, and in the facility;(3) Viewing and intercom systems;(5) Radiation monitors used to indicate room exposure; and(6) Emergency off buttons.(E) A licensee shall arrange for prompt repair of any system identified in 105 CMR 120.581(C) that is not operating properly.(F) If the results of the checks required in 105 CMR 120.581(D) indicate the malfunction of any system, a licensee shall 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.(G) A licensee shall retain a record of each check required by 105 CMR 120.581(C) and (D) in accordance with 105 CMR 120.592(I).Amended by Mass Register Issue 1480, eff. 10/14/2022.