Département de Radio-Oncologie, Centre Hospitalier de l'Université de Montréal-Hôpital Notre-Dame, Montreal, Quebec, Canada.
Radiother Oncol. 2010 Jul;96(1):43-7. doi: 10.1016/j.radonc.2010.03.017. Epub 2010 Apr 8.
To assess the influence of fiducial marker (FM) migration on the matching quality in external beam radiation therapy (EBRT) for prostate cancer.
The position of FMs were identified using on-board kV imaging (OBI) and their 3-D position established using an in-house reconstruction algorithm for 31 patients with prostate adenocarcinoma. To carry out the match, the positions were overlaid on the digitally reconstructed radiographs (DRR) generated from the planning CT. The distance between each FM was calculated for seven treatments throughout the EBRT course. Four radiotherapy technologists were asked to independently perform and rate the match from OBI to DRR which was then correlated to the extent of FM migration.
All the matches were rated by at least three radiotherapy technologists as "very easy" ("easy" subgroup) for 24 patients (77%), while the other seven patients had their match rated less than "very easy" and considered the "not easy" subgroup. The average daily FM migration was 0.93+/-0.34 mm for the "easy" subgroup vs. 1.82+/-0.75 mm for the latter. An average migration >2 mm was seen in five/seven patients in the "not easy" subgroup as compared to none in the "easy" subgroup. There was a trend towards less FM migration and better matching if the planning CT was done later than the day of the FM implant (p=0.093).
FM migration >2 mm predicts for a more difficult matching process; PTV margins might have to be adjusted or the planning CT repeated.
评估在前列腺癌的外照射放射治疗（EBRT）中，基准标记物（FM）迁移对配准质量的影响。
使用机载千伏成像（OBI）识别 FM 的位置，并使用内部重建算法建立其 3D 位置，共纳入 31 例前列腺腺癌患者。为了进行配准，将位置叠加到从计划 CT 生成的数字重建射线照片（DRR）上。在 EBRT 过程中，对每个 FM 进行了七次治疗的位置计算。要求四位放射治疗技师独立进行并从 OBI 到 DRR 进行评分，然后将其与 FM 迁移的程度相关联。
所有的匹配至少有三位放射治疗技师评为“非常容易”（“容易”亚组），共 24 例（77%），而另外 7 例的匹配评分低于“非常容易”，被认为是“不容易”亚组。“容易”亚组的 FM 平均每日迁移量为 0.93+/-0.34mm，而后者为 1.82+/-0.75mm。在“不容易”亚组中，有 5/7 例患者的平均迁移量大于 2mm，而在“容易”亚组中则没有。如果计划 CT 是在 FM 植入后的某一天进行，那么 FM 迁移量较小，匹配效果更好（p=0.093）。
FM 迁移>2mm 预测匹配过程更困难；可能需要调整 PTV 边界或重复进行计划 CT。
