Evaluating the Application of Tissue-Specific Dose Kernels Instead of Water Dose Kernels in Internal Dosimetry: A Monte Carlo Study

Moghadam, Maryam Khazaee; Kamali-Asl, Alireza; Geramifar, Parham; Zaidi, Habib

doi:10.1089/cbr.2016.2117

Cited by 20 publications

(16 citation statements)

References 34 publications

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“…We thus classify our approach as small-scale (sub-organ and cellular level) rather than a true stochastic microdosimetric method, using the titular convention 21 . Use of the DPK kernel allows for extension of this method to other radionuclides 38 or non-water-like tissues such as bone and lungs 39 by generating a new kernel. The authors are currently conducting studies of therapeutically conjugated 225 Ac and 227 Th in a murine model with these methods.…”

Section: Discussionmentioning

confidence: 99%

Small-scale (sub-organ and cellular level) alpha-particle dosimetry methods using an iQID digital autoradiography imaging system

Peter

Sandmaier

Dion

et al. 2022

Sci Rep

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Targeted radiopharmaceutical therapy with alpha-particle emitters (αRPT) is advantageous in cancer treatment because the short range and high local energy deposition of alpha particles enable precise radiation delivery and efficient tumor cell killing. However, these properties create sub-organ dose deposition effects that are not easily characterized by direct gamma-ray imaging (PET or SPECT). We present a computational procedure to determine the spatial distribution of absorbed dose from alpha-emitting radionuclides in tissues using digital autoradiography activity images from an ionizing-radiation quantum imaging detector (iQID). Data from 211At-radioimmunotherapy studies for allogeneic hematopoietic cell transplantation in a canine model were used to develop these methods. Nine healthy canines were treated with 16.9–30.9 MBq 211At/mg monoclonal antibodies (mAb). Lymph node biopsies from early (2–5 h) and late (19–20 h) time points (16 total) were obtained, with 10–20 consecutive 12-µm cryosections extracted from each and imaged with an iQID device. iQID spatial activity images were registered within a 3D volume for dose-point-kernel convolution, producing dose-rate maps. The accumulated absorbed doses for high- and low-rate regions were 9 ± 4 Gy and 1.2 ± 0.8 Gy from separate dose-rate curves, respectively. We further assess uptake uniformity, co-registration with histological pathology, and requisite slice numbers to improve microscale characterization of absorbed dose inhomogeneities in αRPT.

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Section: Discussionmentioning

confidence: 99%

Small-scale (sub-organ and cellular level) alpha-particle dosimetry methods using an iQID digital autoradiography imaging system

Peter

Sandmaier

Dion

et al. 2022

Sci Rep

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“…Density scaling approaches were also applied by Götz et al (2019) in applications to 177 Lu VSVs (termed dose voxel kernels in this study) within tissue heterogeneities. In the study by Moghadam et al (2016), VSVs were computed by MC radiation transport simulation for 90 Y, 177 Lu, and 32 P in 9 different tissues—bone, lung, adipose, breast, heart, intestine, kidney, liver, and spleen—along with S -coefficient scaling factors to account for dose reductions and/or enhancement at tissue interfaces.…”

Section: Calculation Of Absorbed Dosementioning

confidence: 99%

ICRU REPORT 96, Dosimetry-Guided Radiopharmaceutical Therapy

et al. 2021

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The Commission wishes to express its appreciation to the individuals involved in the preparation of this Report for the time and efforts that they devoted to this task and to express its appreciation to the organizations with which they are affiliated.All rights reserved. No part of this book may be reproduced, stored in retrieval systems or transmitted in any form by any means, electronic, electrostatic, magnetic, mechanical photocopying, recording or otherwise, without the permission in writing from the publishers.

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“…The Monte Carlo method is one of the most accurate methods for internal dosimetry calculations, but is time-consuming [10]. On the other hand, analytical methods provide dose estimation in a shorter amount of time, but they are typically restricted to a constant shape and size of the dose calculation medium and radiation source spectra [11,12]. In analytical methods such as those proposed by MIRD (Committee on Medical Internal Radiation Dose), data from SPECT or PET images are used to obtain an approximate estimate of the mean absorbed dose to tumors, which may be far from the actual values [13].…”

Section: Introductionmentioning

confidence: 99%

Optimized cocktail of 90Y/177Lu for radionuclide therapy of neuroendocrine tumors of various sizes: a simulation study

Peer-Firozjaei

Tajik-Mansoury

Geramifar

et al. 2022

Nuclear Medicine Communications

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Background and objectivesThere is significant interest and potential in the treatment of neuroendocrine tumors via peptide receptor radionuclide therapy (PRRT) using one or both of 90 Y and 177 Lu-labeled peptides. Given the presence of different tumor sizes in patients and differing radionuclide dose delivery properties, the present study aims to use Monte Carlo simulations to estimate S-values to spherical tumors of various sizes with 90 Y and 177 Lu separately and in combination. The goal is to determine ratios of 90 Y to 177 Lu that result in the largest absorbed doses per decay of the radionuclides and the most suitable dose profiles to treat tumors of specific sizes. Material and methodsParticle transfer calculations and simulations were performed using the Monte Carlo GATE simulation software. Spherical tumors of different sizes, ranging from 0.5 to 20 mm in radius, were designed. Activities of 177 Lu and 90 Y, individually and in combination, were homogeneously placed within the total volume of the tumors. We determined the S-values to the tumors, and to the external volume outside of the tumors (cross-dose) which was used to approximate background tissue. The dose profiles were obtained for each of the different tumor sizes, and the uniformity of dose within each tumor was calculated.Results For all tumor sizes, the self-dose and crossdose per decay from 90 Y were higher than that from 177 Lu. We observed that 177 Lu had the most uniform dose distribution within tumors with radii less than 5 mm. For tumors greater than 5 mm in radius, a ratio of 25% 90 Y to 75% 177 Lu resulted in the most uniform doses. When the ratio of 177 Lu to 90 Y was smaller, the uniformity improved more with increasing tumor size. The cross-dose stayed approximately constant for tumors larger than 15 mm for all ratios of 177 Lu to 90 Y. Finally, as the size of the tumor increased, differences in the S-values between different ratios of 177 Lu to 90 Y decreased. ConclusionOur work showed that to achieve a more uniform dose distribution within the tumor, 177 Lu alone is more effective for small tumors. For medium and large tumors, a ratio of 90 Y to 177 Lu with more or less 177 Lu, respectively, is recommended.

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Evaluating the Application of Tissue-Specific Dose Kernels Instead of Water Dose Kernels in Internal Dosimetry: A Monte Carlo Study

Cited by 20 publications

References 34 publications

Small-scale (sub-organ and cellular level) alpha-particle dosimetry methods using an iQID digital autoradiography imaging system

Small-scale (sub-organ and cellular level) alpha-particle dosimetry methods using an iQID digital autoradiography imaging system

ICRU REPORT 96, Dosimetry-Guided Radiopharmaceutical Therapy

Optimized cocktail of 90Y/177Lu for radionuclide therapy of neuroendocrine tumors of various sizes: a simulation study

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