Rodgers J E
Department of Radiation Medicine, Georgetown University Hospital, 3800 Reservoir Road NW, Washington, D.C. 20007, USA.
J Appl Clin Med Phys. 2001 Summer;2(3):157-64. doi: 10.1120/jacmp.v2i3.2609.
The additional intensity modulated radiation therapy (IMRT) and total body irradiation (TBI) to conventional treatment clinical treatment procedures can significantly increase the contribution of accelerator head leakage radiation. Previously recommended procedures by the National Council on Radiation Protection and Measurements (NCRP) for vault design, specifically calculations of primary and secondary barrier thicknesses, are not valid when leakage radiation significantly exceeds direct radiation. Use factor distributions are also influenced by IMRT and TBI procedures. Methods are proposed to extend the NCRP barrier design formulas to resolve these problems. The medical accelerator (weekly) workload is separately determined for the direct, leakage, and scatter radiation components. Applications of the formulas to the calculation of primary and secondary barriers are discussed. The addition of IMRT to the shielding design is explored as a function of the fraction patients receiving IMRT and the MU to dose ratio. Secondary barrier thicknesses could be increased by as much as 1 TVL.
与传统治疗临床治疗程序相比，额外的调强放射治疗（IMRT）和全身照射（TBI）会显著增加加速器机头泄漏辐射的影响。当泄漏辐射显著超过直接辐射时，美国国家辐射防护与测量委员会（NCRP）先前推荐的用于治疗室设计的程序，特别是主防护层和次防护层厚度的计算方法不再有效。使用因子分布也会受到IMRT和TBI程序的影响。本文提出了扩展NCRP防护层设计公式的方法来解决这些问题。分别确定了医用加速器（每周）直接辐射、泄漏辐射和散射辐射分量的工作量。讨论了这些公式在主防护层和次防护层计算中的应用。研究了将IMRT添加到屏蔽设计中时，接受IMRT治疗的患者比例和监测单位与剂量比的函数关系。次防护层厚度可能会增加多达1个半价层。
