Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer

Abstract Background Tumour dosimetry after radionuclide therapy using 177Lu-labelled radiopharmaceuticals requires determination of the 177Lu mean concentration, but this is challenging as tumours are often small, or 177Lu activity is present in nearby organs or other tumours. Here we present a comp...

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Main Authors: Peter Frøhlich Staanum, Peter Iversen
Format: Article
Language:English
Published: SpringerOpen 2025-07-01
Series:EJNMMI Physics
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Online Access:https://doi.org/10.1186/s40658-025-00772-1
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author Peter Frøhlich Staanum
Peter Iversen
author_facet Peter Frøhlich Staanum
Peter Iversen
author_sort Peter Frøhlich Staanum
collection DOAJ
description Abstract Background Tumour dosimetry after radionuclide therapy using 177Lu-labelled radiopharmaceuticals requires determination of the 177Lu mean concentration, but this is challenging as tumours are often small, or 177Lu activity is present in nearby organs or other tumours. Here we present a comparison of methods for determination of 177Lu mean concentration, and in turn absorbed tumour dose, applied to a small number of patients with prostate cancer treated by [177Lu]Lu-PSMA I&T. For application of each method, specific criteria on tumour diameter and tumour-background ratio must be fulfilled. Results Eighteen tumours in 9 patients were analyzed. Several methods, the so-called Small Volume of Interest (VOI) with a 20 mm diameter sphere, Large VOI and Isocontour methods, were found to be in good agreement. Relative to the chosen reference method (Isocontour method with partial volume correction), the relative percentage differences of 177Lu concentration using either of these methods were in the range (-23)–26%. The relative differences of absorbed doses were in the range (-16)–19%. Conclusions The agreement between the methods permits a comparison between dosimetry studies, where some of these methods are applied. As the application criteria are complementary, it is possible to include both small (> 15 mm diameter) solitary tumours and larger (> 30 mm diameter), possibly non-solitary, tumours in a dosimetry study.
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spelling doaj-art-58a3a8aab9004e0c9a93c5e7365245fc2025-08-20T03:45:35ZengSpringerOpenEJNMMI Physics2197-73642025-07-0112111810.1186/s40658-025-00772-1Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancerPeter Frøhlich Staanum0Peter Iversen1Department of Nuclear Medicine and PET-Centre, Aarhus University HospitalDepartment of Nuclear Medicine and PET-Centre, Aarhus University HospitalAbstract Background Tumour dosimetry after radionuclide therapy using 177Lu-labelled radiopharmaceuticals requires determination of the 177Lu mean concentration, but this is challenging as tumours are often small, or 177Lu activity is present in nearby organs or other tumours. Here we present a comparison of methods for determination of 177Lu mean concentration, and in turn absorbed tumour dose, applied to a small number of patients with prostate cancer treated by [177Lu]Lu-PSMA I&T. For application of each method, specific criteria on tumour diameter and tumour-background ratio must be fulfilled. Results Eighteen tumours in 9 patients were analyzed. Several methods, the so-called Small Volume of Interest (VOI) with a 20 mm diameter sphere, Large VOI and Isocontour methods, were found to be in good agreement. Relative to the chosen reference method (Isocontour method with partial volume correction), the relative percentage differences of 177Lu concentration using either of these methods were in the range (-23)–26%. The relative differences of absorbed doses were in the range (-16)–19%. Conclusions The agreement between the methods permits a comparison between dosimetry studies, where some of these methods are applied. As the application criteria are complementary, it is possible to include both small (> 15 mm diameter) solitary tumours and larger (> 30 mm diameter), possibly non-solitary, tumours in a dosimetry study.https://doi.org/10.1186/s40658-025-00772-1Radionuclide therapyRadiopharmaceutical therapyTumour dosimetryLu-177Lu-PSMA.
spellingShingle Peter Frøhlich Staanum
Peter Iversen
Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
EJNMMI Physics
Radionuclide therapy
Radiopharmaceutical therapy
Tumour dosimetry
Lu-177
Lu-PSMA.
title Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
title_full Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
title_fullStr Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
title_full_unstemmed Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
title_short Comparison of tumour segmentation methods for dosimetry in [177Lu]Lu-PSMA I&T treated patients with metastatic castration resistant prostate cancer
title_sort comparison of tumour segmentation methods for dosimetry in 177lu lu psma i t treated patients with metastatic castration resistant prostate cancer
topic Radionuclide therapy
Radiopharmaceutical therapy
Tumour dosimetry
Lu-177
Lu-PSMA.
url https://doi.org/10.1186/s40658-025-00772-1
work_keys_str_mv AT peterfrøhlichstaanum comparisonoftumoursegmentationmethodsfordosimetryin177lulupsmaittreatedpatientswithmetastaticcastrationresistantprostatecancer
AT peteriversen comparisonoftumoursegmentationmethodsfordosimetryin177lulupsmaittreatedpatientswithmetastaticcastrationresistantprostatecancer