Practical Nuclear Medicine and Utility of Phantoms for Internal Dosimetry: XCAT Compared with Zubal

Fallahpoor, Maryam; Abbasi, Mehrshad; Kalantari, Faraz; Parach, Ali Asghar; Sen, A. K.

doi:10.1093/rpd/ncw115

Cited by 6 publications

(6 citation statements)

References 20 publications

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“…The internal dosimetry for rabbits was done similar to our previous studies in human and phantom (15)(16)(17)(18) . GATE code is a dedicated code for simulation of the events after administration of nuclear medicine diagnostic and therapeutic radiopharmaceuticals (19) .…”

Section: Discussionmentioning

confidence: 99%

The effect of lithium on radioiodine thyroid tissue ablation

et al. 2021

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Background: Pretreatment with lithium in thyroid cancer patients before radioiodine therapy (RIT) has been suggested to improve the results of therapy in terms of higher radiation to thyroid tissue and limiting extrathyroid irradiation. Materials and Methods: The beta and gamma radiation to the thyroid gland and lungs in 8 female New Zealand rabbits weighing 2.7 to 3.6 kg were simulated employing GATE Monte Carlo code. The study design was before-after and crossover; rabbits were orally treated with 165 to 288 µCi 131 I with or without pretreatment with 60 mg per day lithium. SPECT/CT imaging was done 20 to 24 hours after RIT providing the distribution and attenuation maps for simulation. The S-values were calculated and compared between the rabbits prepared with and without lithium before RIT by analysis of covariance. Results: For beta radiation, the thyroid to lung S-value ratios (TLR) was 10.5 ± 1.6 with lithium pretreatment and 15.9 ± 12.5 without it. For gamma rays, TLR was 4.8 ± 1.8 vs. 6.7 ± 3.1 in rabbits with and without lithium pretreatment. The values of TLR were higher without lithium pretreatment but statistically insignificant. Conclusion: Lithium demonstrated no improvement in radioiodine uptake in thyroid tissue. Pretreatment of differentiated thyroid cancer patients with lithium before RIT, which is backed by old literature, should be reconsidered.

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Section: Discussionmentioning

confidence: 99%

The effect of lithium on radioiodine thyroid tissue ablation

et al. 2021

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“…Then, absorbed dose in four clinically important critical organs for the treatment by 90 Y microspheres including liver, lung, kidney, and bone marrow were calculated. Simulations were performed with GATE, Monte Carlo code with the same method we previously documented . Among other physical interactions, attention has been given to various interactions of electron including Bremsstrahlung .…”

Section: Methodsmentioning

confidence: 99%

“…Patient's dosimetry is possible with simulation methods before the initiation of the treatment or can be calculated after the treatment for follow‐up purposes. We previously used Monte Carlo code for certain conventional imaging and therapeutic agents including Technetium‐99m, Iodine‐131, and Samarium‐153 in different phantoms and in patient. Recently 90 Y became available to us and labeling of the microspheres and clinical trials are under development .…”

Section: Introductionmentioning

confidence: 99%

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Internal dosimetry for radioembolization therapy with Yttrium‐90 microspheres

Fallahpoor

Abbasi

Parach

et al. 2017

J Applied Clin Med Phys

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The absorbed doses in the liver and adjacent viscera in Yttrium‐90 radioembolization therapy for metastatic liver lesions are not well‐documented. We sought for a clinically practical way to determine the dosimetry of this advent treatment. Six different female XCAT BMIs and seven different male XCAT BMIs were generated. Using Monte Carlo GATE code simulation, the total of 100MBq 90Y was deposited uniformly in the source organ, liver. Self‐irradiation and absorbed doses in lung, kidney and bone marrow were calculated. The mean energy of Yittrium‐90 (i.e., 0.937 MeV) was used. The S‐values and equivalent doses in target organs were estimated. The dose absorbed in the liver was between 84 and 53 Gy and below the target of 80 to 150 Gy. The absorbed dose in the bone marrow, lungs, and kidneys are very low and below 0.1 , 0.4, and 0.5 Gy respectively. Our study indicates that larger activities than the conventional dose of 3 GBq may be both required and safe. Further confirmations in clinical settings are needed.

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“…One of the most important factors to be considered in evaluating new radiopharmaceuticals used for treatment and diagnosis is the absorbed dose of radionuclide in the body. At present, patient-specific dosimetry (PSD), known as the most accurate method in internal dosimetry, is used to optimize treatment and diagnosis procedures in nuclear medicine [12]. The PSD calculates the proper radiation dose received to each of the patient's internal organs according to the actual activity distribution of the injected adiopharmaceuticals.…”

Section: Introductionsmentioning

confidence: 99%

Calculation of Gallium-68 Dose Factors for [68Ga] DOTATATE Injected Patients: A Comparison with OLINDA Database

Karimkhani

Yousefnia

Faghihi

et al. 2022

Jonra

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68Ga] DOTATATE as a radiolabeled tracer is used for in vivo detection of neuroendocrine tumors in the PET/CT examinations. This study aims to calculate S-values in various organs in a voxelized-based Monte Carlo simulation approach for each patient individually. PET/CT images of 9 patients suspected of neuroendocrine cancer were acquired 60 minutes after injection of [68Ga] DOTATATE. After reshaping and registering CT images to the size of PET images, GATE/GEANT4 Monte Carlo (MC) toolkit was used with two inputs of CT images as voxelized attenuation map and PET images as a voxelized activity map for the calculation of the different organs dose. Voxelized dose maps were extracted in the target organs for different source organs. S-value volume histogram and absolute S-values based on the MIRD formalism were calculated. The highest S-values were observed for spleen, bladder, kidneys, liver, pituitary, and the lung with 6.26E-05 ± 1.47E-05, 5.17E-05 ± 3.08E-05, 3.41E-05 ± 7.68E-06, 2.08E-05 ± 4.12E-06, 1.62E-05 ± 5.74E-06 and 8.47E-06 ± 2.47E-06 mGy/MBq.S, respectively. The difference between the amounts of the calculated S-values and those presented in OLINDA software is mainly related to the anatomical difference of the patients with the standard phantom in OLINEDA software. This study showed that patient-specific dosimetry is necessary to calculate S-values.

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Practical Nuclear Medicine and Utility of Phantoms for Internal Dosimetry: XCAT Compared with Zubal

Abstract: The results of absorbed doses in Zubal and XCAT phantoms are different. The variations prohibit easy comparison or interchangeability of dosimetry between these phantoms.

Cited by 6 publications

References 20 publications

The effect of lithium on radioiodine thyroid tissue ablation

The effect of lithium on radioiodine thyroid tissue ablation

Internal dosimetry for radioembolization therapy with Yttrium‐90 microspheres

Calculation of Gallium-68 Dose Factors for [68Ga] DOTATATE Injected Patients: A Comparison with OLINDA Database

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