Feasibility of simplifying renal dosimetry in 177Lu peptide receptor radionuclide therapy

Sundlöv, Anna; Gustafsson, Johan; Brolin, Gustav; Mortensen, Nadja; Hermann, Rebecca; Bernhardt, Peter; Svensson, Johanna; Ljungberg, Michael; Tennvall, Jan; Gleisner, Katarina Sjögreen

doi:10.1186/s40658-018-0210-2

Cited by 77 publications

(79 citation statements)

References 26 publications

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“…The simulated time‐activity data for planar imaging were fitted with a mono‐exponential function. The TIAC was then determined with the area under the TAC scaled with the simulated activity value of the quantitative SPECT/CT measurement according to

T I A C = \frac{A_{SPECT} (t_{SPECT})}{A_{planar} (t_{SPECT})} \cdot \frac{1}{A_{0}} \cdot \int_{0}^{\infty} A_{planar} (t) d t,

where A SPECT is the activity value of the simulated SPECT/CT measurement, A planar is the mono‐exponential biokinetic determined by fitting the simulated planar activity data, and A 0 is the injected activity . Furthermore, the TIACs estimated without a SPECT/CT measurement, that is, only with planar imaging, were also calculated.…”

Section: Methodsmentioning

confidence: 99%

“…where A SPECT is the activity value of the simulated SPECT/ CT measurement, A planar is the mono-exponential biokinetic determined by fitting the simulated planar activity data, and A 0 is the injected activity. 6,10,11,13,25 Furthermore, the TIACs estimated without a SPECT/CT measurement, that is, only with planar imaging, were also calculated. As noise was implemented in the simulation routine, 1000 replications were performed for each sampling schedule and virtual patient, that is, 13 9 1000 TIACs were simulated for each sampling schedule.…”

Section: C Simulation Of Renal Tiacsmentioning

confidence: 99%

“…This study focuses on the determination of OSS for renal dosimetry for 177 Lu‐PSMA I&T patients using the hybrid planar/SPECT method . This approach is recommended for dosimetry if quantitative SPECT scans cannot be acquired at multiple time points .…”

Section: Introductionmentioning

confidence: 99%

“…Studies focusing on simplifying dosimetry by minimizing the number of sampling points for renal dosimetry with 177 Lu agents have already been performed by several groups. [5][6][7] In these studies, the dosimetry based on the full time-activity data set was used as ground truth and compared with minimized data sets. Whether the underlying time-activity data were measured under optimal conditions, that is, time points, 5861 Med.…”

Section: Introductionmentioning

confidence: 99%

“…This study focuses on the determination of OSS for renal dosimetry for 177 Lu-PSMA I&T patients using the hybrid planar/SPECT method. 6,[10][11][12][13][14][15] This approach is recommended for dosimetry if quantitative SPECT scans cannot be acquired at multiple time points. 12,14 As the SPECT/CT measurement basically corrects the planar activity data for systematic errors, an enhanced noise model incorporating systematic and stochastic errors was used.…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy

et al. 2019

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Purpose Accurate and precise renal dosimetry during 177Lu‐labeled prostate‐specific membrane antigen (PSMA) radioligand therapy is crucial for therapy decisions. Sampling schedules for estimating the necessary time‐integrated activity coefficients (TIACs) are not optimized and standardized for clinical practice. Therefore, a simulation study to determine optimal sampling schedules (OSSs) was performed on 13 virtual 177Lu‐PSMA I&T therapy patients. Method A total of 880 clinically feasible sampling schedules for planar imaging (three time points) were investigated. To simulate the hybrid planar/SPECT method, an additional quantitative SPECT/CT measurement following one planar image was considered. For each sampling schedule and patient, the activity values were generated separately. Measurement noise was modeled by drawing random numbers of log‐normal distributions. The used fractional standard deviations (FSD) differed depending on the imaging modality. For activity values assigned to planar imaging, systematic noise between 25% and 75% of the total noise was simulated. After fitting with a mono‐exponential function, the root‐mean‐squared errors of the deviations of the simulated TIACs from the ground truth for 1000 replications were used to determine the OSS. The uncertainties of the TIACs and renal dose coefficients were estimated. Results For the hybrid planar/SPECT method, OSSs were determined to be (3–4, 72–76, 124–144)  h post injection (p.i.) with the quantitative SPECT/CT scan shortly after the second measurement. The accuracy and precision of the determined TIACs were in the range of (−3.0 ± 6.2)% and (−1.0  ±  6.5)%. This precision was improved by a factor 2–3 compared to dosimetry based on planar images only. Similar results were obtained for the renal dose coefficients. The virtual patients' renal dose coefficients were (0.68  ± 0.24)  Gy/GBq indicating that a population‐based method yields an uncertainty of 35%. Conclusions Dosimetry based on the hybrid planar/SPECT method with OSS outperforms dosimetry based on planar images. The high variability in dose coefficients between the virtual patients demonstrates the need for individualized dosimetry.

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T I A C = \frac{A_{SPECT} (t_{SPECT})}{A_{planar} (t_{SPECT})} \cdot \frac{1}{A_{0}} \cdot \int_{0}^{\infty} A_{planar} (t) d t,

Section: Methodsmentioning

confidence: 99%

Section: C Simulation Of Renal Tiacsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy

et al. 2019

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A method for tumor dosimetry based on hybrid planar‐SPECT/CT images and semiautomatic segmentation

et al. 2018

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Simplified image‐based dosimetry using planar images and patient‐specific S‐values

Kim,

Suh,

Cheon

et al. 2024

Medical Physics

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BackgroundSingle time point measurement approach and hybrid dosimetry were proposed to simplify the dosimetry process. It is anticipated that utilizing patient‐specific S‐value would enable more accurate dosimetry assessment based on imaging compared to using the conventional MIRD S‐values.PurposeWe performed planar image‐based dosimetry scaled with a single SPECT image for the entire treatment cycle using patient‐specific S‐values (PSS dosimetry) of organs. PSS dosimetry could further simplify the dosimetry procedure compared with a conventional 2D planar/3D SPECT hybrid dosimetry, as PSS dosimetry requires only one SPECT/CT image for the treatment of the entire cycle, whereas the conventional hybrid dosimetry requires a SPECT/CT image for each treatment cycle.Methods177Lu‐DOTATATE SPECT/CT and planar image datasets acquired from Seoul National University Hospital (SNUH, Seoul, Republic of Korea) were utilized for the evaluation. Images were acquired 4, 24, 48, and 120 h after patients’ intravenous injection of 177Lu‐DOTATATE. Dose estimations based on a Monte Carlo (MC) simulation using the Geant4 Application for Emission Tomography (GATE) (v.8.2) were considered as the reference. Planar image‐based dosimetry scaled with a single SPECT image was performed using the patient‐specific S‐value (PSS). Briefly, the CT image was considered as the patient's anatomical reference and PSSs were quantified using the multiple voxel S‐value (VSV) method. Then, PSS dosimetry was performed by obtaining activity information from sequential planar images and a scaling factor derived from a single SPECT/planar image pair. Hybrid dosimetry using sequential planar images and a single SPECT image was performed for comparison. The absorbed doses of the kidneys, bone marrow (BM) in the lumbar spine, liver, and spleen calculated using the PSS and hybrid dosimetries were compared with the reference MC results.ResultsThe mean differences (MDs) of the self‐absorption S‐values between S‐value of OLINDA/EXM and PSS for the kidneys, liver, and spleen were −0.04%, −2.39%, and −2.62%, respectively. However, the differences in the self‐absorption S‐values were significantly higher for the BM (84.99%) and the remainder of the body (ROB) (280.84%). The absorbed doses estimated by the PSS and hybrid dosimetries showed relatively high errors compared with MC simulation result, regardless of the organ. In contrast, the PSS and hybrid dosimetries produced similar dose estimates. For the entire cycles of the treatment, the MDs of absorbed doses between PSS and hybrid dosimetries were −3.31%, −6.04%, 3.37%, and −2.17% for the kidneys, BM, liver, and spleen, respectively. Through a correlation analysis and the Wilcoxon signed‐rank test, we concluded that there was no significant difference between the results obtained by the two dosimetry methods.ConclusionsAs the PSS was derived using CT images with actual anatomical information and organ‐specific volume of interest (VOI), PSS dosimetry provided reliable results. PSS dosimetry was robust in estimating the absorbed dose for the later treatment cycles. Therefore, PSS dosimetry outperformed hybrid dosimetry in terms of dose estimation for a greater number of treatment cycles.

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Feasibility of simplifying renal dosimetry in 177Lu peptide receptor radionuclide therapy

Cited by 77 publications

References 26 publications

Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy

Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy

A method for tumor dosimetry based on hybrid planar‐SPECT/CT images and semiautomatic segmentation

Simplified image‐based dosimetry using planar images and patient‐specific S‐values

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Feasibility of simplifying renal dosimetry in 177Lu peptide receptor radionuclide therapy

Cited by 77 publications

References 26 publications

Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in 177Lu‐PSMA therapy

Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in 177Lu‐PSMA therapy

A method for tumor dosimetry based on hybrid planar‐SPECT/CT images and semiautomatic segmentation

Simplified image‐based dosimetry using planar images and patient‐specific S‐values

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Product

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Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy

Technical Note: Optimal sampling schedules for kidney dosimetry based on the hybrid planar/SPECT method in ¹⁷⁷Lu‐PSMA therapy