使用混合全身平面-SPECT/CT的I-123和I-131成像进行患者特异性I-131剂量测定的准确性。

Accuracy of patient-specific I-131 dosimetry using hybrid whole-body planar-SPECT/CT I-123 and I-131 imaging.

作者信息

Morphis Michaella, van Staden Johan A, du Raan Hanlie, Ljungberg Michael, Sjögreen Gleisner Katarina

机构信息

Department of Medical Physics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa.

Medical Radiation Physics, Lund University, Lund, Sweden.

出版信息

EJNMMI Phys. 2024 Jun 20;11(1):50. doi: 10.1186/s40658-024-00657-9.

DOI:10.1186/s40658-024-00657-9

PMID:38898326

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11187057/

Abstract

PURPOSE

This study aimed to assess the accuracy of patient-specific absorbed dose calculations for tumours and organs at risk in radiopharmaceutical therapy planning, utilizing hybrid planar-SPECT/CT imaging.

METHODS

Three Monte Carlo (MC) simulated digital patient phantoms were created, with time-activity data for mIBG labelled to I-123 (LEHR and ME collimators) and I-131 (HE collimator). The study assessed the accuracy of the mean absorbed doses for I-131-mIBG therapy treatment planning. Multiple planar whole-body (WB) images were simulated (between 1 to 72 h post-injection (p.i)). The geometric-mean image of the anterior and posterior WB images was calculated, with scatter and attenuation corrections applied. Time-activity curves were created for regions of interest over the liver and two tumours (diameters: 3.0 cm and 5.0 cm) in the WB images. A corresponding SPECT study was simulated at 24 h p.i and reconstructed using the OS-EM algorithm, incorporating scatter, attenuation, collimator-detector response, septal scatter and penetration corrections. MC voxel-based absorbed dose rate calculations used two image sets, (i) the activity distribution represented by the SPECT images and (ii) the activity distribution from the SPECT images distributed uniformly within the volume of interest. Mean absorbed doses were calculated considering photon and charged particle emissions, and beta emissions only. True absorbed doses were calculated by MC voxel-based dosimetry of the known activity distributions for reference.

RESULTS

Considering photon and charged particle emissions, mean absorbed dose accuracies across all three radionuclide-collimator combinations of 3.8 ± 5.5% and 0.1 ± 0.9% (liver), 5.2 ± 10.0% and 4.3 ± 1.7% (3.0 cm tumour) and 15.0 ± 5.8% and 2.6 ± 0.6% (5.0 cm tumour) were obtained for image set (i) and (ii) respectively. Considering charged particle emissions, accuracies of 2.7 ± 4.1% and 5.7 ± 0.7% (liver), 3.2 ± 10.2% and 9.1 ± 1.7% (3.0 cm tumour) and 13.6 ± 5.7% and 7.0 ± 0.6% (5.0 cm tumour) were obtained for image set (i) and (ii) respectively.

CONCLUSION

The hybrid WB planar-SPECT/CT method proved accurate for I-131-mIBG dosimetry, suggesting its potential for personalized treatment planning.

摘要

目的

本研究旨在利用平面 - SPECT/CT混合成像评估放射性药物治疗计划中针对肿瘤和危及器官的患者特异性吸收剂量计算的准确性。

方法

创建了三个蒙特卡罗（MC）模拟数字患者体模，包含用I - 123标记的mIBG（低能高分辨率准直器和中能准直器）以及I - 131（高能准直器）的时间 - 活度数据。该研究评估了I - 131 - mIBG治疗计划中平均吸收剂量的准确性。模拟了多个平面全身（WB）图像（注射后1至72小时）。计算了前后WB图像的几何平均图像，并应用了散射和衰减校正。为WB图像中肝脏和两个肿瘤（直径分别为3.0 cm和5.0 cm）的感兴趣区域创建了时间 - 活度曲线。在注射后24小时模拟了相应的SPECT研究，并使用有序子集期望最大化（OS - EM）算法进行重建，纳入了散射、衰减、准直器 - 探测器响应、隔板散射和穿透校正。基于MC体素的吸收剂量率计算使用了两组图像，（i）由SPECT图像表示的活度分布，以及（ii）SPECT图像中的活度分布在感兴趣体积内均匀分布。考虑光子和带电粒子发射以及仅考虑β发射计算了平均吸收剂量。通过基于MC体素的已知活度分布剂量测定法计算真实吸收剂量作为参考。

结果

考虑光子和带电粒子发射时，对于图像集（i）和（ii），在所有三种放射性核素 - 准直器组合中，肝脏的平均吸收剂量准确度分别为3.8±5.5%和0.1±0.9%，3.0 cm肿瘤的为5.2±10.0%和4.3±1.7%，5.0 cm肿瘤的为15.0±5.8%和2.6±0.6%。仅考虑带电粒子发射时，图像集（i）和（ii）中肝脏的准确度分别为2.7±4.1%和5.7±0.7%，3.0 cm肿瘤的为3.2±10.2%和9.1±1.7%，5.0 cm肿瘤的为13.6±5.7%和7.0±0.6%。