Zhang X, Penagaricano J, Han E Y, Morrill S, Hardee M, Liang X, Gupta S K, Corry P M, Ratanatharathom V
Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
Technol Cancer Res Treat. 2015 Aug;14(4):440-6. doi: 10.1177/1533034614556932. Epub 2014 Nov 14.
The objective of this study is to compare the new and conventional tomotherapy treatment techniques and to evaluate dosimetric differences between them. A dosimetric analysis was performed by comparing planning target volume (PTV) median dose, 95% of PTV dose coverage, Paddick conformity index (CI), homogeneity index (HI), whole-body integral dose, and OAR median doses. The beam on time (BOT) and the effect of different jaw sizes and pitch values was studied. The study results indicated that the PTV dose coverage for all the techniques was comparable. Treatment plans using dynamic jaw reduced OAR doses to structures located at the treatment field edge compared to fixed jaw plans. The HT-3DCRT plans resulted in higher OAR doses to kidney, liver, and lung compared to the other techniques, and TD-IMRT provided the best dose sparing to liver compared to other techniques. Whole-body integral dose differences were found to be insignificant among the techniques. BOT was found to be higher for fixed jaw treatment plan compared to dynamic jaw plan and comparable between all treatment techniques with 5-cm dynamic jaw. In studying effect of jaw size, better OAR sparing and HI were found for 2.5-cm jaw but at the expense of doubling of BOT as compared to 5-cm jaw. There was no significant improvement found in OAR sparing when the pitch value was increased. Increasing the pitch from 0.2 to 0.43, the CI was improved, HI improved only for 5-cm jaw size, and BOT decreased to approximately half of its original time.
本研究的目的是比较新型和传统断层放疗治疗技术，并评估它们之间的剂量差异。通过比较计划靶区（PTV）中位剂量、PTV剂量覆盖的95%、帕迪克适形指数（CI）、均匀性指数（HI）、全身积分剂量和危及器官（OAR）中位剂量进行剂量分析。研究了照射时间（BOT）以及不同准直器大小和螺距值的影响。研究结果表明，所有技术的PTV剂量覆盖情况相当。与固定准直器计划相比，使用动态准直器的治疗计划降低了位于治疗野边缘结构的OAR剂量。与其他技术相比，HT-3DCRT计划导致肾脏、肝脏和肺部的OAR剂量更高，而TD-IMRT与其他技术相比为肝脏提供了最佳的剂量 sparing。发现各技术之间的全身积分剂量差异不显著。发现固定准直器治疗计划的BOT高于动态准直器计划，并且在所有使用5厘米动态准直器的治疗技术之间相当。在研究准直器大小的影响时，发现2.5厘米准直器对OAR的 sparing更好且HI更佳，但与5厘米准直器相比BOT增加了一倍。当螺距值增加时，未发现OAR sparing有显著改善。将螺距从0.2增加到0.43，CI得到改善，HI仅在5厘米准直器大小时得到改善，且BOT减少到原来时间的大约一半。
