Duggan Dennis M, Ding George X, Coffey Charles W, Kirby Wyndee, Hallahan Dennis E, Malcolm Arnold, Lu Bo
Vanderbilt University, Department of Radiation Oncology, B1003 Preston Research Building, Nashville, TN 37232-5671, United States.
Lung Cancer. 2007 Apr;56(1):77-88. doi: 10.1016/j.lungcan.2006.11.012. Epub 2006 Dec 13.
We report our initial experience with deep-inspiration breath-hold (DIBH) cone-beam CT (CBCT) on the treatment table, using the kilovoltage imager integrated into our linear accelerator, for setting up patients for DIBH stereotactic body radiation therapy (SBRT) for lung tumors. Nine patients with non-small cell lung cancer (seven stage I), were given 60Gy in three fractions. All nine patients could perform a DIBH for 35s. For each patient we used a diagnostic reference CT volume image acquired during a DIBH to design an SBRT plan consisting of 7-10 noncoplanar conformal beams. Four patients were setup by registering DIBH kilovoltage projection radiographs or megavoltage portal images on the treatment table to digitally reconstructed radiographs from the reference CT. Each of the last 14 fractions out of a total of 27 was setup by acquiring a CBCT volume image on the treatment table in three breath-holds. The CBCT and reference CT volume images were directly registered and the shift was calculated from the registration. The CBCT volume images contained excellent detail on soft tissue and bony anatomy for matching to the reference CT. Most importantly, the tumor was always clearly visible in the CBCT images, even when it was difficult or impossible to see in the radiographs or portal images. The accuracy of the CBCT method was confirmed by DIBH megavoltage portal imaging and each treatment beam was delivered during a DIBH. CBCT acquisition typically required five more minutes than radiograph acquisition but the overall setup time was often shorter using CBCT because repeat imaging was minimized. We conclude that for setting up SBRT treatments of lung tumors, DIBH CBCT is feasible, fast and may result in less variation among observers than using bony anatomy in orthogonal radiographs.
我们报告了在治疗台上使用集成于直线加速器的千伏成像仪进行深吸气屏气（DIBH）锥形束CT（CBCT）的初步经验，用于为肺癌患者进行DIBH立体定向体部放射治疗（SBRT）的摆位。9例非小细胞肺癌患者（7例为I期）接受了3次分割、每次60Gy的治疗。所有9例患者均能进行35秒的DIBH。对于每位患者，我们使用在DIBH期间获取的诊断参考CT容积图像来设计由7 - 10个非共面适形射束组成的SBRT计划。4例患者通过在治疗台上配准DIBH千伏投影射线照片或兆伏级射野图像与参考CT的数字重建射线照片来进行摆位。在总共27次分割中的最后14次分割，每次均通过在治疗台上进行3次屏气获取CBCT容积图像来进行摆位。将CBCT和参考CT容积图像直接配准，并根据配准计算位移。CBCT容积图像在软组织和骨解剖结构方面具有出色的细节，便于与参考CT匹配。最重要的是，即使在射线照片或射野图像中难以或无法看到肿瘤时，在CBCT图像中肿瘤始终清晰可见。通过DIBH兆伏级射野成像证实了CBCT方法的准确性，并且每次治疗射束均在DIBH期间投照。CBCT采集通常比射线照片采集多需要5分钟，但由于重复成像最少，使用CBCT时总体摆位时间通常更短。我们得出结论，对于肺癌的SBRT治疗摆位，DIBH CBCT是可行、快速的，并且与在正交射线照片中使用骨解剖结构相比，观察者之间的差异可能更小。
