Makrigiorgos G, Antonadou D, Proukakis C, Throuvalas N
Department of Medical Physics, University of Athens, Greece.
Med Phys. 1989 Mar-Apr;16(2):302-4. doi: 10.1118/1.596382.
The restricted dose mean linear energy transfer (LET) (L500,D) of the stray radiation field a few centimeters outside the treatment volume has been measured for 12 and 18 MV photons produced by a clinical Therac-20 (AECL) accelerator. The measurements were performed as a function of field size and distance from the edge of the treatment volume, using the method of the high-pressure ionization chamber. Contrary to what was found in a previous investigation for a clinical Co-60 unit and despite the presence of photoneutrons (in the case of 18 MV photons), the L500,D outside the beam does not increase significantly relative to the L500,D of the primary beam.
已使用高压电离室测量了由临床Therac - 20（加拿大原子能公司）加速器产生的12兆伏和18兆伏光子在治疗体积外几厘米处的杂散辐射场的受限剂量平均线能量转移（LET）（L500,D）。测量是作为射野大小和距治疗体积边缘距离的函数进行的。与先前对临床钴 - 60装置的研究结果相反，并且尽管存在光中子（在18兆伏光子的情况下），射束外的L500,D相对于原射线的L500,D并未显著增加。
