Le Deroff Coralie, Berger Lucie, Bellec Julien, Boissonnat Guillaume, Chesneau Héléna, Chiavassa Sophie, Desrousseaux Julie, Gempp Stéphanie, Henry Olivier, Jarril Jimmy, Lazaro Delphine, Lefeuvre Ronan, Passal Vincent, Solinhac Fanny, Lafond Caroline, Delpon Gregory
Centre Eugène Marquis (Unicancer), Rennes, France.
Centre Jean Perrin (Unicancer), Clermont Ferrand, France.
Phys Imaging Radiat Oncol. 2022 Feb 26;21:108-114. doi: 10.1016/j.phro.2022.02.004. eCollection 2022 Jan.
Image-guided radiotherapy (IGRT) involves frequent in-room imaging sessions contributing to additional patient irradiation. The present work provided patient-specific dosimetric data related to different imaging protocols and anatomical sites.
We developed a Monte Carlo based software able to calculate 3D personalized dose distributions for five imaging devices delivering kV-CBCT (Elekta and Varian linacs), MV-CT (Tomotherapy machines) and 2D-kV stereoscopic images from BrainLab and Accuray. Our study reported the dose distributions calculated for pelvis, head and neck and breast cases based on dose volume histograms for several organs at risk.
2D-kV imaging provided the minimum dose with less than 1 mGy per image pair. For a single kV-CBCT and MV-CT, median dose to organs were respectively around 30 mGy and 15 mGy for the pelvis, around 7 mGy and 10 mGy for the head and neck and around 5 mGy and 15 mGy for the breast. While MV-CT dose varied sparsely with tissues, dose from kV imaging was around 1.7 times higher in bones than in soft tissue. Daily kV-CBCT along 40 sessions of prostate radiotherapy delivered up to 3.5 Gy to the femoral heads. The dose level for head and neck and breast appeared to be lower than 0.4 Gy for every organ in case of a daily imaging session.
This study showed the dosimetric impact of IGRT procedures. Acquisition parameters should therefore be chosen wisely depending on the clinical purposes and tailored to morphology. Indeed, imaging dose could be reduced up to a factor 10 with optimized protocols.
图像引导放射治疗（IGRT）需要频繁进行室内成像，这会增加患者的辐射剂量。本研究提供了与不同成像方案和解剖部位相关的患者特异性剂量学数据。
我们开发了一款基于蒙特卡罗方法的软件，能够计算五种成像设备的三维个性化剂量分布，这些设备包括提供千伏级锥形束CT（Elekta和Varian直线加速器）、兆伏级CT（螺旋断层放射治疗机）以及来自BrainLab和Accuray的二维千伏级立体图像。我们的研究报告了根据多个危及器官的剂量体积直方图计算出的骨盆、头颈部和乳腺病例的剂量分布。
二维千伏级成像提供的剂量最低，每对图像的剂量小于1毫戈瑞。对于单次千伏级锥形束CT和兆伏级CT，骨盆部位各器官的中位剂量分别约为30毫戈瑞和15毫戈瑞，头颈部约为7毫戈瑞和10毫戈瑞，乳腺约为5毫戈瑞和15毫戈瑞。虽然兆伏级CT的剂量随组织变化不大，但千伏级成像在骨骼中的剂量比在软组织中高约1.7倍。在前列腺放射治疗的40个疗程中，每日进行千伏级锥形束CT检查会给股骨头带来高达3.5戈瑞的剂量。在每日进行成像检查的情况下，头颈部和乳腺各器官的剂量水平似乎低于0.4戈瑞。
本研究显示了IGRT程序的剂量学影响。因此，应根据临床目的明智地选择采集参数，并根据形态进行调整。实际上，通过优化方案，成像剂量可降低至十分之一。
