El Outmani Amine, Zerfaoui M, Hattal I, Oulhouq Y, Bahhous K, Rrhioua A, Bakari D, Hamal M, Moussa A
Faculty of Sciences, LPMR FSO Mohammed First University, 60000, Oujda, Morocco.
Centre Oriental Al Kindy, Oncologie et Diagnostic du Maroc (ODM), Oujda, Morocco.
Phys Eng Sci Med. 2025 Jul 21. doi: 10.1007/s13246-025-01592-4.
The majority of treatment centers currently use Cone Beam Computed Tomography (CBCT) as an effective method of patient repositioning, opening up the prospect of using it in treatment plans calculation. The purpose of this task is to investigate the feasibility of utilizing kV-CBCT images as a potential alternative to CT scans for generating treatment plans during radiation therapy. The images are taken by the imaging system installed on a linear accelerator and implemented in a Treatment Planning System (TPS). This imaging system opens the possibility to proceed to dose calculation using a calibration curve that establishes a link between voxel attenuation in Hounsfield Units (HU) and electron densities relative to water (RED). Furthermore, a comparison of Volumetric Modulated Arc Therapy (VMAT) treatment plans on this imaging modality was done to the Computed Tomography (CT) imaging system using the CIRS phantom. The comparison is also performed the images of 10 patients with right breast cancer. VMAT plans from the two modalities were compared in terms of target coverage, normal tissue sparing, dose distribution parameters, and monitor units (MUs). Then, the gamma index test is employed by using the PTW Verisoft to compare the TPS calculated dose distribution for the two modalities. It is also used to compare the measured dose distribution performed by the Portal Dosimetry. Regarding the volume-dose parameters of the PTV and the Organs at risk (OARs), no differences were found between the VMAT plans of the two imaging modalities, CT and CBCT. Additionally, the gamma analysis results of the patients VMAT plans for 1%-1 mm, 2%-2 mm, 3%-3 mm, 4%-4 mm and 5%-5 mm showed that more than 84%, 90%, 92%, 94%, and 96%, respectively, of the points agreed upon between Eclipse calculated and measured dose distributions for the CT and CBCT VMAT plans. The good dosimetric agreement (gamma index reaches more than 92% for 3%-3 mm) between breast VMAT plans based on CT and CBCT images renders the latter an appealing verification tool and a substitute for CT images, if needed, for dose calculation. CBCT images are an effective option for direct dose calculation or to do adaptive radiotherapy in the case of a breast cancer.
目前，大多数治疗中心使用锥形束计算机断层扫描（CBCT）作为患者重新定位的有效方法，为其在治疗计划计算中的应用开辟了前景。本任务的目的是研究在放射治疗期间利用千伏CBCT图像作为CT扫描的潜在替代方法来生成治疗计划的可行性。这些图像由安装在线性加速器上的成像系统采集，并在治疗计划系统（TPS）中实施。该成像系统开启了使用校准曲线进行剂量计算的可能性，该校准曲线建立了Hounsfield单位（HU）中的体素衰减与相对于水的电子密度（RED）之间的联系。此外，使用CIRS体模，对该成像模态下的容积调强弧形治疗（VMAT）治疗计划与计算机断层扫描（CT）成像系统进行了比较。还对10例右乳腺癌患者的图像进行了比较。从靶区覆盖、正常组织保护、剂量分布参数和监测单位（MU）等方面对两种模态的VMAT计划进行了比较。然后，使用PTW Verisoft进行伽马指数测试，以比较TPS计算的两种模态的剂量分布。它还用于比较门静脉剂量测定法执行的测量剂量分布。关于计划靶体积（PTV）和危及器官（OARs）的体积剂量参数，在CT和CBCT这两种成像模态的VMAT计划之间未发现差异。此外，对患者VMAT计划的1%-1毫米、2%-2毫米、3%-3毫米、4%-4毫米和5%-5毫米的伽马分析结果表明，CT和CBCT VMAT计划在Eclipse计算和测量的剂量分布之间，分别有超过84%、90%、92%、94%和96%的点一致。基于CT和CBCT图像的乳腺VMAT计划之间良好的剂量学一致性（3%-3毫米时伽马指数超过92%）使得CBCT图像成为一种有吸引力的验证工具，并且在需要时可替代CT图像进行剂量计算。CBCT图像是乳腺癌直接剂量计算或进行自适应放射治疗的有效选择。
