Nakaguchi Yuji, Ono Takeshi, Maruyama Masato, Shimohigashi Yoshinobu, Kai Yudai
Department of Radiological Technology, Kumamoto University Hospital, Kumamoto, Japan.
Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
J Appl Clin Med Phys. 2017 Jul;18(4):69-75. doi: 10.1002/acm2.12103. Epub 2017 Jun 2.
Stereotactic body radiation therapy (SBRT) involves the delivery of substantially larger doses over fewer fractions than conventional therapy. Therefore, SBRT treatments will strongly benefit patients using vivo patient dose verification, because the impact of the fraction is large. For in vivo measurements, a commercially available quality assurance (QA) system is the COMPASS system (IBA Dosimetry, Germany). For measurements, the system uses a new transmission detector (Dolphin, IBA Dosimetry). In this study, we evaluated the method for in vivo 3D dose reconstruction for SBRT using this new transmission detector. We confirmed the accuracy of COMPASS with Dolphin for SBRT using multi leaf collimator (MLC) test patterns and clinical SBRT cases. We compared the results between the COMPASS, the treatment planning system, the Kodak EDR2 film, and the Monte Carlo (MC) calculations. MLC test patterns were set up to investigate various aspects of dose reconstruction for SBRT: (a) simple open fields (2 × 2-10 × 10 cm ), (b) a square wave chart pattern, and (c) the MLC position detectability test in which the MLCs were changed slightly. In clinical cases, we carried out 6 and 8 static IMRT beams for SBRT in the lung and liver. For MLC test patterns, the differences between COMPASS and MC were around 3%. The COMPASS with the dolphin system showed sufficient resolution in SBRT. For clinical cases, COMPASS can detect small changes for the dose profile and dose-volume histogram. COMPASS also showed good agreement with MC. We can confirm the feasibility of SBRT QA using the COMPASS system with Dolphin. This method was successfully operated using the new transmission detector and verified by measurements and MC.
立体定向体部放射治疗（SBRT）与传统治疗相比，在较少的分次治疗中给予的剂量要大得多。因此，SBRT治疗将极大地受益于使用体内患者剂量验证的患者，因为分次剂量的影响很大。对于体内测量，一种市售的质量保证（QA）系统是COMPASS系统（德国IBA剂量学公司）。该系统在测量时使用一种新型透射探测器（Dolphin，IBA剂量学公司）。在本研究中，我们评估了使用这种新型透射探测器对SBRT进行体内三维剂量重建的方法。我们通过多叶准直器（MLC）测试模式和临床SBRT病例，证实了COMPASS与Dolphin用于SBRT的准确性。我们比较了COMPASS、治疗计划系统、柯达EDR2胶片和蒙特卡罗（MC）计算之间的结果。设置MLC测试模式以研究SBRT剂量重建的各个方面：（a）简单开放野（2×2 - 10×10 cm），（b）方波图表模式，以及（c）MLC位置可检测性测试，其中MLC略有变化。在临床病例中，我们对肺部和肝脏的SBRT进行了6束和8束静态调强放疗（IMRT）。对于MLC测试模式，COMPASS与MC之间的差异约为3%。带有Dolphin系统的COMPASS在SBRT中显示出足够的分辨率。对于临床病例，COMPASS可以检测到剂量分布和剂量体积直方图的微小变化。COMPASS与MC也显示出良好的一致性。我们可以确认使用带有Dolphin的COMPASS系统进行SBRT质量保证的可行性。该方法使用新型透射探测器成功运行，并通过测量和MC进行了验证。
