Abstract：
OBJECTIVE: This study aims to compare the calculated absorbed dose in target organs and tumors obtained using the different imaging protocols and the calculation methodologies implemented by HERMES HybridViewer dosimetry software for 177Lu-PSMA I&T and 177Lu-DOTATATE therapy.
METHODS: Multiple time-point whole-body planar images and one SPECT/CT image were acquired from 18 patients including 177Lu-PSMA I&T (13 patients) and 177Lu-DOTATATE treatment (5 patients) after administration of 3.80-8.58 GBq injected activity. The regions of interest were drawn in the whole body, kidneys, liver, urinary bladder, salivary glands, and tumors to determine the time-integrated activity (TIA) in source organs. Absorbed doses in target organs were calculated according to the Medical Internal Radiation Dose (MIRD) scheme using the HERMES HybridViewer dosimetry integrated with OLINDA/EXM V.2.1 that utilizes the non-uniform rational B-splines (NURBS) for computational digital phantom.
RESULTS: The planar-based dosimetry showed a higher dose per injected activity compared to the hybrid-based dosimetry, primarily due to organ overlap. The highest difference in absorbed dose between the imaging scenarios was observed in the spleen with a variation of up to 51.6%, while the difference for other target organs and tumors was less than 40%.
CONCLUSIONS: The dosimetry calculation derived from the 2D planar-based method consistently demonstrates a significantly higher absorbed dose in organs and tumors compared with the hybrid-based method. However, the hybrid method outperforms the planar method in terms of tumor visualization and overlap-free organ delineation.
METHODS: Multiple time-point whole-body planar images and one SPECT/CT image were acquired from 18 patients including 177Lu-PSMA I&T (13 patients) and 177Lu-DOTATATE treatment (5 patients) after administration of 3.80-8.58 GBq injected activity. The regions of interest were drawn in the whole body, kidneys, liver, urinary bladder, salivary glands, and tumors to determine the time-integrated activity (TIA) in source organs. Absorbed doses in target organs were calculated according to the Medical Internal Radiation Dose (MIRD) scheme using the HERMES HybridViewer dosimetry integrated with OLINDA/EXM V.2.1 that utilizes the non-uniform rational B-splines (NURBS) for computational digital phantom.
RESULTS: The planar-based dosimetry showed a higher dose per injected activity compared to the hybrid-based dosimetry, primarily due to organ overlap. The highest difference in absorbed dose between the imaging scenarios was observed in the spleen with a variation of up to 51.6%, while the difference for other target organs and tumors was less than 40%.
CONCLUSIONS: The dosimetry calculation derived from the 2D planar-based method consistently demonstrates a significantly higher absorbed dose in organs and tumors compared with the hybrid-based method. However, the hybrid method outperforms the planar method in terms of tumor visualization and overlap-free organ delineation.
摘要：
目的：本研究旨在比较使用不同成像方案和HERMESHybridViewer剂量测定软件在177Lu-PSMAI&T和177Lu-DOTATATE治疗中获得的靶器官和肿瘤的计算吸收剂量。
方法：从18例患者中获取了多个时间点全身平面图像和一个SPECT/CT图像，包括177Lu-PSMAI＆T（13例）和177Lu-DOTATATE治疗（5例）。注射3.80-8.58GBq的活动。感兴趣的区域被绘制在整个身体中，肾脏，肝脏,膀胱,唾液腺,和肿瘤来确定源器官的时间整合活性（TIA）。根据医学内部辐射剂量（MIRD）方案，使用与OLINDA/EXMV.2.1集成的HERMESHybridViewer剂量测定法计算靶器官的吸收剂量，该剂量利用非均匀有理B样条（NURBS）进行计算数字体模。
结果：与基于混合的剂量测定法相比，基于平面的剂量测定法显示每次注射活动的剂量更高，主要是由于器官重叠。在脾脏中观察到成像方案之间吸收剂量的最高差异，变化高达51.6％，而其他靶器官和肿瘤的差异小于40％。
结论：基于2D平面的方法得出的剂量测定计算始终表明，与基于混合的方法相比，器官和肿瘤的吸收剂量明显更高。然而,在肿瘤可视化和无重叠器官勾画方面，混合方法优于平面方法。
方法：从18例患者中获取了多个时间点全身平面图像和一个SPECT/CT图像，包括177Lu-PSMAI＆T（13例）和177Lu-DOTATATE治疗（5例）。注射3.80-8.58GBq的活动。感兴趣的区域被绘制在整个身体中，肾脏，肝脏,膀胱,唾液腺,和肿瘤来确定源器官的时间整合活性（TIA）。根据医学内部辐射剂量（MIRD）方案，使用与OLINDA/EXMV.2.1集成的HERMESHybridViewer剂量测定法计算靶器官的吸收剂量，该剂量利用非均匀有理B样条（NURBS）进行计算数字体模。
结果：与基于混合的剂量测定法相比，基于平面的剂量测定法显示每次注射活动的剂量更高，主要是由于器官重叠。在脾脏中观察到成像方案之间吸收剂量的最高差异，变化高达51.6％，而其他靶器官和肿瘤的差异小于40％。
结论：基于2D平面的方法得出的剂量测定计算始终表明，与基于混合的方法相比，器官和肿瘤的吸收剂量明显更高。然而,在肿瘤可视化和无重叠器官勾画方面，混合方法优于平面方法。
