PDF(Pubmed)
Abstract：
OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
摘要：
目的：图像引导放射治疗（IGRT）涉及频繁的室内成像会话，有助于额外的患者照射。本工作提供了与不同成像协议和解剖部位相关的患者特异性剂量测定数据。
方法：我们开发了一种基于蒙特卡洛的软件，能够为提供kV-CBCT（Elekta和Varianlinacs）的五种成像设备计算3D个性化剂量分布。来自BrainLab和Accuray的MV-CT（断层治疗机）和2D-kV立体图像。我们的研究报告了骨盆计算的剂量分布，基于多个危险器官的剂量体积直方图的头颈部和乳房病例。
结果：2D-kV成像提供了每个图像对小于1mGy的最小剂量。对于单个kV-CBCT和MV-CT，骨盆对器官的中位剂量分别约为30mGy和15mGy，头部和颈部约7mGy和10mGy，乳房约5mGy和15mGy。虽然MV-CT剂量随组织变化稀疏，kV成像的剂量在骨骼中比在软组织中高约1.7倍。每天进行40次前列腺放疗的kV-CBCT，股骨头最高可达3.5Gy。在每天成像的情况下，每个器官的头颈部和乳房的剂量水平似乎低于0.4Gy。
结论：本研究显示了IGRT程序的剂量学影响。因此,采集参数应根据临床目的进行明智选择,并根据形态学进行调整。的确,成像剂量可以减少到10倍与优化方案。
方法：我们开发了一种基于蒙特卡洛的软件，能够为提供kV-CBCT（Elekta和Varianlinacs）的五种成像设备计算3D个性化剂量分布。来自BrainLab和Accuray的MV-CT（断层治疗机）和2D-kV立体图像。我们的研究报告了骨盆计算的剂量分布，基于多个危险器官的剂量体积直方图的头颈部和乳房病例。
结果：2D-kV成像提供了每个图像对小于1mGy的最小剂量。对于单个kV-CBCT和MV-CT，骨盆对器官的中位剂量分别约为30mGy和15mGy，头部和颈部约7mGy和10mGy，乳房约5mGy和15mGy。虽然MV-CT剂量随组织变化稀疏，kV成像的剂量在骨骼中比在软组织中高约1.7倍。每天进行40次前列腺放疗的kV-CBCT，股骨头最高可达3.5Gy。在每天成像的情况下，每个器官的头颈部和乳房的剂量水平似乎低于0.4Gy。
结论：本研究显示了IGRT程序的剂量学影响。因此,采集参数应根据临床目的进行明智选择,并根据形态学进行调整。的确,成像剂量可以减少到10倍与优化方案。
