Myers Pamela, Stathakis Sotirios, Gutiérrez Alonso N, Esquivel Carlos, Mavroidis Panayiotis, Papanikolaou Niko
Department of Radiology and Radiation Oncology, Cancer Therapy and Research Center at University of Texas Health Science Center at San Antonio, 7979 Wurzbach Rd, San Antonio, USA.
J Med Phys. 2012 Apr;37(2):72-80. doi: 10.4103/0971-6203.94741.
For routine quality assurance of helical tomotherapy plans, an alternative method, as opposed to the TomoTherapy suggested cylindrical solid water phantom with film and ionization chamber, is proposed using the PTW Seven29 2D-ARRAY inserted in a dedicated octagonal phantom, called Octavius. First, the sensitivity of the array to pitch was studied by varying the pitch during planning to 0.287, 0.433, 1.0, and 2.0. For each pitch selected, the dependence on field size was investigated by generating plans with field widths (FWs) of 1.06 cm, 2.49 cm, and 5.02 cm, for a total of 12 plans. Secondly, a total of 15 patient QA plans were delivered using helical tomotherapy with the Delta(4) and Seven29/Octavius for comparison. Using the clinical gamma criteria, 3% and 3 mm, all FW and pitch plans had a passing percentage of >90%. For patient QA plans, the average gamma pass percentage was 97.0% (94.4-99.8%) for the Delta(4) and 97.6% (92.5-100.0%) for the Seven29/Octavius. Both the Seven29/Octavius and Delta(4) performed to a high standard of measurement accuracy and had a 90% or greater gamma percent for all plans and were considered clinically acceptable.
对于螺旋断层放射治疗计划的常规质量保证，提出了一种替代方法，与TomoTherapy建议的带有胶片和电离室的圆柱形固体水模体不同，该方法使用插入专用八角形模体（称为Octavius）中的PTW Seven29二维阵列。首先，通过在计划过程中将螺距改变为0.287、0.433、1.0和2.0来研究阵列对螺距的敏感性。对于每个选定的螺距，通过生成场宽（FW）为1.06 cm、2.49 cm和5.02 cm的计划来研究对阵列尺寸的依赖性，总共12个计划。其次，使用螺旋断层放射治疗分别采用Delta(4)和Seven29/Octavius交付了总共15个患者质量保证计划进行比较。使用临床伽马标准（3%和3 mm），所有场宽和螺距计划的通过率均>90%。对于患者质量保证计划，Delta(4)的平均伽马通过率为97.0%（94.4 - 99.8%），Seven29/Octavius的平均伽马通过率为97.6%（92.5 - 100.0%）。Seven29/Octavius和Delta(4)均达到了高标准的测量精度，所有计划的伽马通过率均达到90%或更高，被认为在临床上是可接受的。
