Department of Medical Physics, Addenbrooke's Hospital, Cambridge, UK.
Radiother Oncol. 2013 Dec;109(3):482-6. doi: 10.1016/j.radonc.2013.09.011. Epub 2013 Oct 12.
To measure the geometric uncertainty resulting from intra-fraction motion and intra-observer image matching, for patients having image-guided prostate radiotherapy on TomoTherapy.
All patients had already been selected for prostate radiotherapy on TomoTherapy, with daily MV-CT imaging. The study involved performing an additional MV-CT image at the end of treatment, on 5 occasions during the course of 37 treatments. 54 patients were recruited to the study. A new formula was derived to calculate the PTV margin for intra-fraction motion.
The mean values of the intra-fraction differences were 0.0mm, 0.5mm, 0.5mm and 0.0° for LR, SI, AP and roll, respectively. The corresponding standard deviations were 1.1mm, 0.8mm, 0.8mm and 0.6° for systematic uncertainties (Σ), 1.3mm, 2.0mm, 2.2mm and 0.3° for random uncertainties (σ). This intra-fraction motion requires margins of 2.2mm in LR, 2.1mm in SI and 2.1mm in AP directions. Inclusion of estimates of the effect of rotations and matching errors increases these margins to approximately 4mm in LR and 5mm in SI and AP directions.
A new margin recipe has been developed to calculate margins for intra-fraction motion. This recipe is applicable to any measurement technique that is based on the difference between images taken before and after treatment.
测量由于分次内运动和同机者图像匹配而导致的几何不确定性，针对在 TomoTherapy 上进行图像引导前列腺放射治疗的患者。
所有患者均已选择在 TomoTherapy 上进行前列腺放射治疗，并进行每日 MV-CT 成像。本研究涉及在 37 次治疗过程中的 5 次治疗结束时进行额外的 MV-CT 成像。共有 54 名患者被纳入研究。推导出了一种新的公式来计算分次内运动的 PTV 边界。
分次内差异的平均值分别为 0.0mm、0.5mm、0.5mm 和 0.0°，用于 LR、SI、AP 和滚动方向。相应的标准偏差分别为 1.1mm、0.8mm、0.8mm 和 0.6°，用于系统性不确定性（Σ），1.3mm、2.0mm、2.2mm 和 0.3°，用于随机性不确定性（σ）。这种分次内运动需要在 LR、SI 和 AP 方向上分别留出 2.2mm、2.1mm 和 2.1mm 的边界。包括旋转和匹配误差影响的估计值会将这些边界分别增加到 LR 方向上约 4mm，以及 SI 和 AP 方向上约 5mm。
已经开发了一种新的边界配方来计算分次内运动的边界。该配方适用于任何基于治疗前后图像差异的测量技术。
