Nichol Alan M, Brock Kristy K, Lockwood Gina A, Moseley Douglas J, Rosewall Tara, Warde Padraig R, Catton Charles N, Jaffray David A
Radiation Medicine Program, Princess Margaret Hospital and University of Toronto, Toronto, Canada.
Int J Radiat Oncol Biol Phys. 2007 Jan 1;67(1):48-56. doi: 10.1016/j.ijrobp.2006.08.021. Epub 2006 Nov 2.
To describe prostate deformation during radiotherapy and determine the margins required to account for prostate deformation after setup to intraprostatic fiducial markers (FM).
Twenty-five patients with T1c-T2c prostate cancer had three gold FMs implanted. The patients presented with a full bladder and empty rectum for two axial magnetic resonance imaging (MRI) scans using a gradient recalled echo (GRE) sequence capable of imaging the FMs. The MRIs were done at the time of radiotherapy (RT) planning and a randomly assigned fraction. A single observer contoured the prostate surfaces. They were entered into a finite element model and aligned using the centroid of the three FMs.
During RT, the prostate volume decreased by 0.5%/fraction (p = 0.03) and the FMs in-migrated by 0.05 mm/fraction (p < 0.05). Prostate deformation was unrelated to differential bladder and bowel filling, but was related to a transurethral resection of the prostate (TURP) (p = 0.003). The standard deviation for systematic uncertainty of prostate surface contouring was 0.8 mm and for FM centroid localization was 0.4 mm. The standard deviation of random interfraction prostate deformation was 1.5 mm and for FM centroid variability was 1.1 mm. These uncertainties from prostate deformation can be incorporated into a margin recipe to determine the total margins required for RT.
During RT, the prostate exhibited: volume decrease, deformation, and in-migration of FMs. Patients with TURPs were prone to prostate deformation.
描述放疗期间前列腺的变形情况，并确定在设置前列腺内基准标记物（FM）后考虑前列腺变形所需的边界。
25例T1c - T2c期前列腺癌患者植入了三个金质FM。患者在膀胱充盈且直肠排空的状态下，使用能够对FM成像的梯度回波（GRE）序列进行两次轴向磁共振成像（MRI）扫描。MRI扫描在放疗（RT）计划时以及随机分配的一个分次进行。由一名观察者勾勒出前列腺表面。将其输入有限元模型，并使用三个FM的质心进行对齐。
在RT期间，前列腺体积以0.5%/分次的速度减小（p = 0.03），FM向内迁移0.05 mm/分次（p < 0.05）。前列腺变形与膀胱和肠道的不同充盈状态无关，但与经尿道前列腺切除术（TURP）有关（p = 0.003）。前列腺表面轮廓系统不确定性的标准差为0.8 mm，FM质心定位的标准差为0.4 mm。分次间前列腺随机变形的标准差为1.5 mm，FM质心变异性的标准差为1.1 mm。这些来自前列腺变形的不确定性可纳入边界处方中，以确定RT所需的总边界。
在RT期间，前列腺表现出：体积减小、变形以及FM向内迁移。接受TURP的患者易于发生前列腺变形。
