Kaiser Adeel, Schultheiss Timothy E, Wong Jeffrey Y C, Smith David D, Han Chunhui, Vora Nayana L, Pezner Richard D, Chen Yi-Jen, Radany Eric H
Department of Radiation Oncology, University of California Irvine, Orange, CA, USA.
Int J Radiat Oncol Biol Phys. 2006 Nov 1;66(3):949-55. doi: 10.1016/j.ijrobp.2006.05.055. Epub 2006 Sep 1.
To use pretreatment megavoltage-computed tomography (MVCT) scans to evaluate positioning variations in pitch, roll, and yaw for patients treated with helical tomotherapy.
Twenty prostate and 15 head-and-neck cancer patients were selected. Pretreatment MVCT scans were performed before every treatment fraction and automatically registered to planning kilovoltage CT (KVCT) scans by bony landmarks. Image registration data were used to adjust patient setups before treatment. Corrections for pitch, roll, and yaw were recorded after bone registration, and data from fractions 1-5 and 16-20 were used to analyze mean rotational corrections.
For prostate patients, the means and standard deviations (in degrees) for pitch, roll, and yaw corrections were -0.60 +/- 1.42, 0.66 +/- 1.22, and -0.33 +/- 0.83. In head-and-neck patients, the means and standard deviations (in degrees) were -0.24 +/- 1.19, -0.12 +/- 1.53, and 0.25 +/- 1.42 for pitch, roll, and yaw, respectively. No significant difference in rotational variations was observed between Weeks 1 and 4 of treatment. Head-and-neck patients had significantly smaller pitch variation, but significantly larger yaw variation, than prostate patients. No difference was found in roll corrections between the two groups. Overall, 96.6% of the rotational corrections were less than 4 degrees.
The initial rotational setup errors for prostate and head-and-neck patients were all small in magnitude, statistically significant, but did not vary considerably during the course of radiotherapy. The data are relevant to couch hardware design for correcting rotational setup variations. There should be no theoretical difference between these data and data collected using cone beam KVCT on conventional linacs.
利用治疗前兆伏级计算机断层扫描（MVCT）评估螺旋断层放射治疗患者在俯仰、横滚和偏航方向上的定位变化。
选取20例前列腺癌患者和15例头颈癌患者。在每个治疗分次前进行治疗前MVCT扫描，并通过骨性标记自动与计划千伏级CT（KVCT）扫描进行配准。图像配准数据用于在治疗前调整患者体位。在骨配准后记录俯仰、横滚和偏航的校正值，并使用第1 - 5分次和第16 - 20分次的数据来分析平均旋转校正值。
对于前列腺癌患者，俯仰、横滚和偏航校正的平均值及标准差（单位：度）分别为 -0.60 ± 1.42、0.66 ± 1.22和 -0.33 ± 0.83。对于头颈癌患者，俯仰、横滚和偏航的平均值及标准差（单位：度）分别为 -0.24 ± 1.19、-0.12 ± 1.53和0.25 ± 1.42。在治疗的第1周和第4周之间，未观察到旋转变化有显著差异。头颈癌患者的俯仰变化明显小于前列腺癌患者，但偏航变化明显大于前列腺癌患者。两组之间的横滚校正无差异。总体而言，96.6%的旋转校正小于4度。
前列腺癌和头颈癌患者的初始旋转摆位误差在数值上均较小，具有统计学意义，但在放射治疗过程中变化不大。这些数据与用于校正旋转摆位变化的治疗床硬件设计相关。这些数据与在传统直线加速器上使用锥形束KVCT收集的数据在理论上应无差异。
