TY - JOUR
T1 - A projection-domain low-count quantitative SPECT method for α-particle emitting radiopharmaceutical therapy
AU - Li, Zekun
AU - Benabdallah, Nadia
AU - Abou, Diane S.
AU - Baumann, Brian C.
AU - Dehdashti, Farrokh
AU - Ballard, David H.
AU - Liu, Jonathan
AU - Jammalamadaka, Uday
AU - Laforest, Richard
AU - Wahl, Richard L.
AU - Thorek, Daniel L.J.
AU - Jha, Abhinav K.
N1 - Publisher Copyright:
Author
PY - 2022
Y1 - 2022
N2 - Single-photon emission computed tomography (SPECT) provides a mechanism to estimate regional isotope uptake in lesions and at-risk organs after administration of α-particle-emitting radiopharmaceutical therapies (α-RPTs). However, this estimation task is challenging due to the complex emission spectra, the very low number of detected counts ( 20 times lower than in conventional SPECT), the impact of stray-radiation-related noise at these low counts, and the multiple image-degrading processes in SPECT. The conventional reconstruction-based quantification methods are observed to be erroneous for α-RPT SPECT. To address these challenges, we developed a low-count quantitative SPECT (LC-QSPECT) method that directly estimates the regional activity uptake from the projection data (obviating the reconstruction step), compensates for stray-radiation-related noise, and accounts for the radioisotope and SPECT physics, including the isotope spectra, scatter, attenuation, and collimator-detector response, using a Monte Carlo-based approach. The method was validated in the context of three-dimensional SPECT with 223Ra, a commonly used radionuclide for α-RPT. Validation was performed using both realistic simulation studies, including a virtual clinical trial, and synthetic and 3D-printed anthropomorphic physical-phantom studies. Across all studies, the LC-QSPECT method yielded reliable regional-uptake estimates and outperformed the conventional ordered subset expectation maximization (OSEM)-based reconstruction and geometric transfer matrix (GTM)-based post-reconstruction partial-volume compensation methods. Further, the method yielded reliable uptake across different lesion sizes, contrasts, and different levels of intra-lesion heterogeneity. Additionally, the variance of the estimated uptake approached the Cramér-Rao bound-defined theoretical limit. In conclusion, the proposed LC-QSPECT method demonstrated the ability to perform reliable quantification for α-RPT SPECT.
AB - Single-photon emission computed tomography (SPECT) provides a mechanism to estimate regional isotope uptake in lesions and at-risk organs after administration of α-particle-emitting radiopharmaceutical therapies (α-RPTs). However, this estimation task is challenging due to the complex emission spectra, the very low number of detected counts ( 20 times lower than in conventional SPECT), the impact of stray-radiation-related noise at these low counts, and the multiple image-degrading processes in SPECT. The conventional reconstruction-based quantification methods are observed to be erroneous for α-RPT SPECT. To address these challenges, we developed a low-count quantitative SPECT (LC-QSPECT) method that directly estimates the regional activity uptake from the projection data (obviating the reconstruction step), compensates for stray-radiation-related noise, and accounts for the radioisotope and SPECT physics, including the isotope spectra, scatter, attenuation, and collimator-detector response, using a Monte Carlo-based approach. The method was validated in the context of three-dimensional SPECT with 223Ra, a commonly used radionuclide for α-RPT. Validation was performed using both realistic simulation studies, including a virtual clinical trial, and synthetic and 3D-printed anthropomorphic physical-phantom studies. Across all studies, the LC-QSPECT method yielded reliable regional-uptake estimates and outperformed the conventional ordered subset expectation maximization (OSEM)-based reconstruction and geometric transfer matrix (GTM)-based post-reconstruction partial-volume compensation methods. Further, the method yielded reliable uptake across different lesion sizes, contrasts, and different levels of intra-lesion heterogeneity. Additionally, the variance of the estimated uptake approached the Cramér-Rao bound-defined theoretical limit. In conclusion, the proposed LC-QSPECT method demonstrated the ability to perform reliable quantification for α-RPT SPECT.
KW - α-particle therapies
KW - Image reconstruction
KW - Isotopes
KW - Lesions
KW - Medical treatment
KW - Plasmas
KW - Quantitative SPECT
KW - Radium-223.
KW - Single photon emission computed tomography
KW - Task analysis
KW - low counts
KW - regional quantification
UR - http://www.scopus.com/inward/record.url?scp=85130802710&partnerID=8YFLogxK
U2 - 10.1109/TRPMS.2022.3175435
DO - 10.1109/TRPMS.2022.3175435
M3 - Article
AN - SCOPUS:85130802710
SN - 2469-7311
SP - 1
JO - IEEE Transactions on Radiation and Plasma Medical Sciences
JF - IEEE Transactions on Radiation and Plasma Medical Sciences
ER -