Image-guided radiation therapy (IGRT) adds an additional imaging radiation dose to existing levels of therapeutic radiation. The extra radiation dose received by organs from multiple conae beam computed tomography (CBCT) scans can increase the probability of the secondary cancer risk. In this study, an effort has been made to assess CBCT dose and image quality for standard pre-sets defined for different organs namely, the chest, pelvis, brain, head and neck, and abdomen. The second goal was to investigate whether the radiation dose could be reduced while still achieving high image quality. Image quality was evaluated on the CatPhan Model 503 (Phantom Lab, NY), while organ kV- CBCT doses were evaluated using an Unfors device (Fluke Biomedical) to provide representative measurements for clinical settings. Nominal CBCT projections with reduced exposure times were reconstructed in 3D using the Unfiltered and Filtered-back Projection algorithms. Patient organ dose (mGy) per procedure for brain, chest, pelvis, abdomen, and head and neck were 7.9, 35.3, 28.1, 58.3, and 0.77, respectively. The experimental analysis suggests that adequate image quality could be obtained while decreasing the number of radiographic projections. Reducing the number of the radiographic projections will reduce the scan time and therefore the imaging dose. The proposed method provides an opportunity to reduce the organ doses comparatively lower than the standard CT doses for head and body protocols. The study provides a framework for delivering low radiation doses to critical organs with no risk of long-term exposure.

图像引导放射治疗 (IGRT) 为现有的治疗辐射水平增加了额外的成像辐射剂量。器官从多个锥形束计算机断层扫描 (CBCT) 扫描中接收到的额外辐射剂量会增加继发性癌症风险的可能性。在这项研究中，已努力评估针对不同器官（即胸部、骨盆、大脑、头颈部和腹部）定义的标准预设的 CBCT 剂量和图像质量。第二个目标是研究是否可以减少辐射剂量，同时仍能实现高图像质量。图像质量在 CatPhan Model 503（Phantom Lab，NY）上进行评估，而器官 kV-CBCT 剂量使用 Unfors 设备（Fluke Biomedical）进行评估，以提供临床环境的代表性测量值。使用未过滤和过滤后投影算法在 3D 中重建具有减少曝光时间的标称 CBCT 投影。脑、胸部、骨盆、腹部和头颈部每次手术的患者器官剂量 (mGy) 分别为 7.9、35.3、28.1、58.3 和 0.77。实验分析表明，在减少射线照相投影数量的同时可以获得足够的图像质量。减少射线照相投影的数量将减少扫描时间并因此减少成像剂量。所提出的方法提供了减少器官剂量的机会，该剂量相对低于头部和身体协议的标准 CT 剂量。该研究为向关键器官提供低辐射剂量提供了一个框架，没有长期暴露的风险。