van Elmpt Wouter, Nijsten Sebastiaan, Petit Steven, Mijnheer Ben, Lambin Philippe, Dekker André
Department of Radiation Oncology (MAASTRO), GROW Research Institute, University Medical Centre Maastricht, Maastricht, The Netherlands.
Int J Radiat Oncol Biol Phys. 2009 Apr 1;73(5):1580-7. doi: 10.1016/j.ijrobp.2008.11.051.
To develop a method that reconstructs, independently of previous (planning) information, the dose delivered to patients by combining in-room imaging with transit dose measurements during treatment.
A megavoltage cone-beam CT scan of the patient anatomy was acquired with the patient in treatment position. During treatment, delivered fields were measured behind the patient with an electronic portal imaging device. The dose information in these images was back-projected through the cone-beam CT scan and used for Monte Carlo simulation of the dose distribution inside the cone-beam CT scan. Validation was performed using various phantoms for conformal and IMRT plans. Clinical applicability is shown for a head-and-neck cancer patient treated with IMRT.
For single IMRT beams and a seven-field IMRT step-and-shoot plan, the dose distribution was reconstructed within 3%/3mm compared with the measured or planned dose. A three-dimensional conformal plan, verified using eight point-dose measurements, resulted in a difference of 1.3 +/- 3.3% (1 SD) compared with the reconstructed dose. For the patient case, planned and reconstructed dose distribution was within 3%/3mm for about 95% of the points within the 20% isodose line. Reconstructed mean dose values, obtained from dose-volume histograms, were within 3% of prescribed values for target volumes and normal tissues.
We present a new method that verifies the dose delivered to a patient by combining in-room imaging with the transit dose measured during treatment. This verification procedure opens possibilities for offline adaptive radiotherapy and dose-guided radiotherapy strategies taking into account the dose distribution delivered during treatment sessions.
开发一种方法，通过在治疗期间将室内成像与传输剂量测量相结合，独立于先前（计划）信息来重建输送给患者的剂量。
在患者处于治疗位置时获取患者解剖结构的兆伏级锥形束CT扫描。在治疗期间，使用电子门静脉成像设备在患者后方测量输送的射野。这些图像中的剂量信息通过锥形束CT扫描进行反向投影，并用于锥形束CT扫描内剂量分布的蒙特卡罗模拟。使用各种体模对适形和调强放疗计划进行验证。展示了对头颈部癌患者进行调强放疗的临床适用性。
对于单束调强放疗射束和七野调强放疗步进式射野计划，与测量或计划剂量相比，剂量分布重建误差在3%/3mm以内。使用八点剂量测量验证的三维适形计划，与重建剂量相比，差异为1.3±3.3%（1标准差）。对于患者病例，在20%等剂量线内约95%的点，计划和重建的剂量分布在3%/3mm以内。从剂量体积直方图获得的重建平均剂量值，对于靶区和正常组织，在规定值的3%以内。
我们提出了一种新方法，通过将室内成像与治疗期间测量的传输剂量相结合来验证输送给患者的剂量。这种验证程序为离线自适应放疗和考虑治疗期间输送的剂量分布的剂量引导放疗策略开辟了可能性。
