Evaluation of the scattered radiation components produced in a gamma camera using Monte Carlo method

Polo, Ivón Oramas

doi:10.1590/rbeb.2014.015

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…Dose tumour (rad)= Activity total (mCi) × 184000 × UPTAKE tumour m tumour (g) (7) The lung shunt fraction was calculated by different methods involving 1-the standard whole-body scan (peak140 keV), 2-AC-SC from SPECT/CT, 3-NoAC-SC from SPECT, and 4-the scatter corrected whole-body scan (SC-WBS).…”

Section: Methodsmentioning

confidence: 99%

“…However, in case the scattering angle is small, the interaction may be accepted as true event with a shifted position up to a few centimetres from the origin of emission. 7 To this end, the potential effect of scatter and attenuation correction has not been extensively explored in 90 Y radioembolization dosimetry. Consequently, this study aimed to elucidate the impact of attenuation and scatter correction on the lungs' shunt fraction and the liver compartments dose.…”

Section: Introductionmentioning

confidence: 99%

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Simplification of Dosimetry in 90Y-Radioembolization Therapy Using Dual Planar Images.

Abuqbeitah¹,

Akdağ²,

Demir³

et al. 2021

Preprint

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Aim: The purpose was to provide practical and effective method for performing 90Y dosimetry with 99mTc-MAA. The impact of scatter and attenuation correction (AC) on the injected 90Y activity and absorbed doses to critical organs was also further target beyond this study.Material and Methods: 18 patients (F: 3, M: 15) were subjected to 90Y therapy. 99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by a whole-body scan (WBS) with peak-window at 140 keV (15% width), and one down-scatter window. SPECT/CT scan was acquired over the lungs and liver regions. The lung shunt fractions were fashioned from the standard WBS, scatter corrected WBS, only scatter corrected SPECT and SPECT/CT with attenuation and scatter correction. The absorbed doses to tumor and surrounding healthy tissue were estimated with alternative approaches involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSF (SC-WBS), AC-SC+LSF (WBS), and NoAC-NoSC+LSF (WBS).Results: The average LSF deviations between the standard LSF and those obtained from AC-SC, NoAC-SC, and SC-WBS was -50% (-29/-71), -32%(-8/-67), and -45%(-13/80), respectively. The prescribed 90Y activity (GBq/Gy) was decreased by a range of 2-11%, 1-9%, and 2-7% with using LSFs from AC-SC, NoAC-SC, SC-WBS images. The absorbed dose to tumour and healthy liver tissue were calculated as 112±90 Gy and 30±18 Gy/GBq by AC-SC (SPECT/CT), 117±108 and 30±22 by NoAC-SC (SPECT), 110±100 and 31±21 Gy/GBq by NoAC-NoSC+LSF (SC-WBS), 106±84 and 28±17 Gy/GBq by AC-SC+LSF (WBS), while the absorbed dose was 90±85 and 28±20 Gy/GBq by using NoAC-NoSC+ LSF (WBS). Overall, no significant difference (p< 0.05) in the tomour and the health liver dose between all the approaches with/and without scatter correction. However, the scatter correction caused a significant difference in the lung shunt fractions (p <0.05).Conclusion: Scatter correction has a significant effect on the lung shunt fractions, planned activity and number of 90Y treatments. However, a minimal or negligible change was occurred on the absorbed dose to tumours and surrounding healthy liver. The good agreement between SPECT/CT approach, and scatter corrected whole-body scan might be practical and effective route for 90Y dosimetry.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simplification of Dosimetry in 90Y-Radioembolization Therapy Using Dual Planar Images.

Abuqbeitah¹,

Akdağ²,

Demir³

et al. 2021

Preprint

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show abstract

Simplification of dosimetry in 90Y-radioembolization therapy by dual planar images

et al. 2022

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Aim The purpose was to provide a practical and effective method for performing reliable 90Y dosimetry based on 99mTc-MAA and SPEC/CT. The impact of scatter correction (SC) and attenuation correction (AC) on the injected 90Y activity, lung shunt fraction (LSF) and the delivered dose to lung and liver compartments was investigated within the scope of the study. Material and methods Eighteen eligible patients (F: 3, M: 15) were subjected to 90Y therapy. 99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by whole-body scan (WBS) with peak-window at 140 keV (15% width) and one down-scatter window. SPECT/CT scan was subsequently acquired encompassing lung and liver regions. The LSFs were fashioned from standard WBS LSFwb (St), scatter corrected WBS LSFwb (Sc), only scatter corrected SPECT LSFspect (NoAC-SC) and SPECT/CT with attenuation and scatter correction LSFspect (AC-SC). The absorbed doses that would be delivered to tumor and injected healthy liver were estimated using different calculation modes involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSFwb (SC), AC-SC + LSFwb (St), and NoAC-NoSC+LSFwb (St). Results The average deviations (range) in LSF values between standard LSFwb (St) and those from SPECT/CT (AC-SC), SPECT (NoAC-SC), and LSFwb (SC) were − 50% (− 29/− 71), − 32% (− 8/− 67), and − 45% (− 13/80), respectively. The suggested 90Y activity (GBq/Gy) was decreased within a range of 2-11%, 1-9%, and 2-7% by using LSFspect (AC-SC), LSFspect (NoAC-SC), and LSFwb (SC), respectively. Overall, two-sample t-test yielded no statistically significant difference (p < 0.05) in the absorbed doses to tumor and injected healthy liver between AC-SC (SPECT) and the rest of approaches with/and without AC and SC. However, a statistically significant difference (p < 0.05) was demonstrated in the lung shunt fractions and lung doses due to AC and SC. The LSFs from scatter corrected planar images LSFwb (SC) exhibited well agreement (R2 = 0.92) with SPECT/CT (AC-SC) and there was no statistically significant difference (Pvalue > 0.05) between both methods. Conclusion It was deduced that SPECT/CT with attenuation and scatter correction plays a crucial role in the measurements of lung shunt fraction and dose as well as the total number of 90Y treatments. However, the absorbed dose to tumors and injected healthy liver was minimally affected by AC and SC. Besides, a good agreement was observed between LSF datasets from SPECT/CT versus scatter corrected WBS that can be alternatively and effectively used in 90Y dosimetry.

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Determination of Gamma Camera’s Calibration Factors for Quantitation of Diagnostic Radionuclides in Simultaneous Scattering and Attenuation Correction

Asgari

Ashoor

Sarkhosh

et al. 2019

CRP

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Evaluation of the scattered radiation components produced in a gamma camera using Monte Carlo method

Cited by 3 publications

References 8 publications

Simplification of Dosimetry in 90Y-Radioembolization Therapy Using Dual Planar Images.

Simplification of Dosimetry in 90Y-Radioembolization Therapy Using Dual Planar Images.

Simplification of dosimetry in 90Y-radioembolization therapy by dual planar images

Determination of Gamma Camera’s Calibration Factors for Quantitation of Diagnostic Radionuclides in Simultaneous Scattering and Attenuation Correction

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