Sánchez-Nieto B, Sánchez-Doblado F, Terrón J A
Depto. Fisiología Médica y Biofísica, Universidad de Sevilla, Spain.
Radiother Oncol. 1997 Jan;42(1):77-85. doi: 10.1016/s0167-8140(96)01857-9.
As for conventional radiotherapy, one of the basic requirements in Total Body Irradiation (TBI) is to know accurately the dose delivered to the entire body. Both the dosimetry and the treatment planning need to be improved. Physical, technical and dosimetrical aspects of TBI have been widely discussed in the literature. However, to our knowledge, no planning systems specifically designed for TBI are commercially available. This article describes a CT-aided PC-based planning system (TBI-Plansys) and its dose calculation algorithm, which applies scatter and inhomogeneity corrections, developed for the TBI technique currently in use at our centre (AP/PA irradiation with patient positioned on his side).
A description of the material and method followed in the dosimetrical procedure is included as it constitutes the basis of the proposed dose calculation algorithm (more than 2D). A Windows programming environment has been used to develop the software.
TBI-Plansys uses patient CT data and indicates absolute and relative dose distributions along midline (at reference points), the transversal axis at the specification point and on transverse sections. The system also calculates the appropriate thicknesses of bolus and shielding to modify undesired dose distributions. TBI-Plansys has been checked against two other well-established systems (beam-zone method and our in vivo semiconductor probe-based system). The checks showed good accuracy with dose differences less than 1% and 3% for homogeneous and inhomogeneous tissues, respectively.
CT calculations by TBI-Plansys allow us to detect undesired distributions which may go unnoticed by calculations at only some specific points. The system has shown clear advantages for routine clinical use as it generates more detailed and accurate information than manual calculations and diminishes the time requirements.
对于传统放疗而言，全身照射（TBI）的基本要求之一是准确知晓传递至全身的剂量。剂量测定和治疗计划都需要改进。TBI的物理、技术和剂量测定方面在文献中已有广泛讨论。然而，据我们所知，尚无专门为TBI设计的商业可用计划系统。本文描述了一种基于CT辅助的基于PC的计划系统（TBI - Plansys）及其剂量计算算法，该算法应用了散射和不均匀性校正，是为我们中心目前使用的TBI技术（患者侧卧时的前后/后前照射）开发的。
包括剂量测定过程中所采用材料和方法的描述，因为它构成了所提出的剂量计算算法（超过二维）的基础。已使用Windows编程环境来开发该软件。
TBI - Plansys使用患者的CT数据，并显示沿中线（在参考点）、指定点处的横向轴以及横断面上的绝对和相对剂量分布。该系统还计算用于修改不期望剂量分布的等效物和屏蔽的适当厚度。已将TBI - Plansys与另外两个成熟的系统（射野区方法和我们基于体内半导体探头的系统）进行了对照检查。检查显示，对于均匀和不均匀组织，剂量差异分别小于1%和3%，具有良好的准确性。
TBI - Plansys的CT计算使我们能够检测到仅在某些特定点进行计算时可能未被注意到的不期望分布。该系统在常规临床应用中显示出明显优势，因为它比手动计算生成更详细和准确的信息，并减少了时间需求。
