scholarly journals CALCULATION OF CONVERSION COEFFICIENTS FOR VOXELIZED PHANTOMS FOR CRITICALITY ACCIDENT DOSIMETRY

2020 ◽  
Vol 191 (1) ◽  
pp. 9-24
Author(s):  
M-A Chevallier ◽  
J B Pontier ◽  
H Morin ◽  
M Duluc ◽  
S Evo ◽  
...  
Keyword(s):  
Dose Calculation ◽  
Organ Dose ◽  
The Body ◽  
Organ Doses ◽  
Simulation Tools ◽  
Criticality Accident ◽  
Anthropomorphic Phantoms ◽  
Conversion Coefficients ◽  
Neutron Component ◽  
Key Parameter

Abstract In the event of a criticality accident, not only the maximal doses received by the victims must be determined but it is also crucial to evaluate the doses to the different organs. With a neutron component, morphology is a key parameter in the organ dose calculation. As the simulation tools can be time consuming to proceed, especially if morphology is taken into account, for all the victims, it may be very useful to have a database of conversion coefficients that allow to obtain the organ doses from the dose measured in the dosemeter for different kinds of morphology. In this paper, we present a study performed to evaluate such conversion coefficients using voxelized anthropomorphic phantoms. These coefficients take into account two crucial parameters having an impact on the dose at the organs: the orientation of the victim in the radiation field and the morphology, that is to say the body mass index of the different victims.

scholarly journals Estimating Specific Patient Organ Dose for Chest CT Examinations with Monte Carlo Method

2021 ◽  
Vol 11 (19) ◽  
pp. 8961
Author(s):  
Yang Yang ◽  
Weihai Zhuo ◽  
Yiyang Zhao ◽  
Tianwu Xie ◽  
Chuyan Wang ◽  
...  
Keyword(s):  
Body Size ◽  
Organ Dose ◽  
Chest Ct ◽  
The Body ◽  
Patient Specific ◽  
Ct Scanner ◽  
Chinese Adults ◽  
Organ Doses ◽  
Specific Patient ◽  
Patient Size

Purpose: The purpose of this study was to preliminarily estimate patient-specific organ doses in chest CT examinations for Chinese adults, and to investigate the effect of patient size on organ doses. Methods: By considering the body-size and body-build effects on the organ doses and taking the mid-chest water equivalent diameter (WED) as a body-size indicator, the chest scan images of 18 Chinese adults were acquired on a multi-detector CT to generate the regional voxel models. For each patient, the lungs, heart, and breasts (glandular breast tissues for both breasts) were segmented, and other organs were semi-automated segmented based on their HU values. The CT scanner and patient models simulated by MCNPX 2.4.0 software (Los Alamos National LaboratoryLos Alamos, USA) were used to calculate lung, breast, and heart doses. CTDIvol values were used to normalize simulated organ doses, and the exponential estimation model between the normalized organ dose and WED was investigated. Results: Among the 18 patients in this study, the simulated doses of lung, heart, and breast were 18.15 ± 2.69 mGy, 18.68 ± 2.87 mGy, and 16.11 ± 3.08 mGy, respectively. Larger patients received higher organ doses than smaller ones due to the higher tube current used. The ratios of lung, heart, and breast doses to the CTDIvol were 1.48 ± 0.22, 1.54 ± 0.20, and 1.41 ± 0.13, respectively. The normalized organ doses of all the three organs decreased with the increase in WED, and the normalized doses decreased more obviously in the lung and the heart than that in the breasts. Conclusions: The output of CT scanner under ATCM is positively related to the attenuation of patients, larger-size patients receive higher organ doses. The organ dose normalized by CTDIvol was negatively correlated with patient size. The organ doses could be estimated by using the indicated CTDIvol combined with the estimated WED.

PATIENT-SPECIFIC ORGAN DOSES FROM PEDIATRIC HEAD CT EXAMINATIONS

2020 ◽  
Vol 191 (1) ◽  
pp. 1-8
Author(s):  
W J Garzón ◽  
D F A Aldana ◽  
V F Cassola
Keyword(s):  
Absorbed Dose ◽  
Organ Dose ◽  
Patient Specific ◽  
Specific Information ◽  
Organ Doses ◽  
Red Bone Marrow ◽  
Head Ct ◽  
Absorbed Doses ◽  
Specific Organ ◽  
Conversion Coefficients

Abstract The aim of this work was to estimate patient’s organ absorbed doses from pediatric helical head computed tomography (CT) examinations using the Size-Specific Dose Estimate (SSDE) methodology and to determine organ dose to SSDE conversion coefficients for clinical routine. Patient-specific organ and tissue absorbed doses from 139 Head CT scans performed in pediatric patients from 0 to 15 years old in a Public Hospital in Tunja, Colombia were estimated. The calculations were made through Monte Carlo simulations, based on patient-specific information, dosimetric CT quantities (CTDIvol, DLP) and age-specific computational human phantoms matched to patients on the basis of gender and size. SSDE showed to be a good quantity for estimate patient-specific organ doses from pediatric head CT examinations when appropriate phantom’s attenuation-based size metrics are chosen to match for any patient size. Strong correlations between absorbed dose and SSDE were found for skin (R2 = 0.99), brain (R2 = 0.98) and eyes (R2 = 0.97), respectively. Besides, a good correlation between SSDE and absorbed dose to the red bone marrow (tissue extended outside the scan coverage) was observed (R2 = 0.94). SSDE-to-organ-dose conversion coefficients obtained in this study provide a practical way to estimate patient-specific organ head CT doses.

Organ dose conversion coefficients based on a voxel mouse model and MCNP code for external photon irradiation

2011 ◽  
Vol 148 (1) ◽  
pp. 9-19 ◽  
Author(s):  
X. Zhang ◽  
X. Xie ◽  
J. Cheng ◽  
J. Ning ◽  
Y. Yuan ◽  
...  
Keyword(s):  
Mouse Model ◽  
Organ Dose ◽  
Mcnp Code ◽  
Photon Irradiation ◽  
Conversion Coefficients

scholarly journals Three-dimensional digital representation of human phantom for organ dose calculation.

1984 ◽  
Vol 19 (3) ◽  
pp. 215-218
Author(s):  
Hiroshi YAMAGUCHI ◽  
Syozo HONGO ◽  
Hiroshi TAKESHITA ◽  
Takashi MARUYAMA ◽  
Mitsue CHIBA
Keyword(s):  
Three Dimensional ◽  
Dose Calculation ◽  
Organ Dose ◽  
Digital Representation

Proton Dose Conversion Coefficients Based on Chinese Reference Adult Woman Voxel Phantom

2013 ◽  
Author(s):  
Fangfang Liu ◽  
Mingqi Shen ◽  
Taosheng Li ◽  
Chunyu Liu
Keyword(s):  
Effective Dose ◽  
Reference Data ◽  
Absorbed Dose ◽  
The Body ◽  
Adult Woman ◽  
Voxel Model ◽  
Conversion Coefficients ◽  
Computational Phantoms ◽  
Posterior Anterior ◽  
Anterior Posterior

In order to calculate the dose conversion coefficients for proton, the voxel model of Chinese Reference Adult Woman (CRAW) was established by the Monte Carlo transport code FLUKA according to the Chinese reference data and the Asian reference data. Compared with the reference data, the deviations of the mass for organs or tissues of CRAW is less than ±5%. Calculations have been performed for 14 incident monoenergetic protons energies from 0.02GeV to 10TeV at the irradiation incident of anterior-posterior (AP) and posterior-anterior (PA). The results of fluence-to-effective dose conversion coefficients are compared with data from the different models such as an anthropomorphic mathematical model, ICRP reference adult voxel model, the voxel-based visible Chinese human (VCH). Anatomical differences among various computational phantoms and the spatial geometric positions of the organs or tissues lead to the discrepancies of the effective dose conversion coefficients in the ranging from a negligible level to 107% at proton energies below 0.2GeV. The deviations of the coefficients, above 0.2GeV, are mostly within 10%. The results of fluence-to-organ absorbed dose conversion coefficients are compared with the data of VCH. The deviations of the coefficients, below and above 0.2GeV, are within 150% and 20%, respectively. The primary factors of the deviations for the coefficients should be due to the differences of the organ mass and the size of the body shape.

Radiotherapy dose calculations in high-Z materials: comprehensive comparison between experiment, Monte Carlo, and conventional planning algorithms (Preprint)

2021 ◽  
Author(s):  
Zhangkai Cheng ◽  
Regina Bromley ◽  
Brad Oborn ◽  
Jeremy Booth
Keyword(s):  
Monte Carlo ◽  
Radiation Therapy ◽  
Spinal Metastases ◽  
Dose Calculation ◽  
High Energy ◽  
The Body ◽  
Treatment Technique ◽  
Calculation Algorithms ◽  
Dose Calculation Algorithms ◽  
Ct Density

BACKGROUND Despite spinal metastases accounting for 10% to 30% of new tumors diagnoses annually, and radiation therapy is a standard treatment technique, the studies discussing the effects of small-size spinal prostheses on spinal radiation therapy are limited. OBJECTIVE To compare the accuracies of the AAA and AcurosXB dose calculation algorithms and to predict the change in the down-stream and lateral dose deposition of high energy photons in the presence of material with densities higher that commonly found in the body. METHODS Metal rods of titanium (d =4.5g/m2), stainless steel (d=8g/cm2) and tungsten (d=19.25 g/cm2) were positioned in a phantom. Film was position behind and laterally to the rods to measure the dose distribution for a 6 MV, 18 MV and 10 FFF photon beams. A DOSXYZnrc Monte Carlo simulation of the experimental setup was performed The AAA and AcurosXB dose calculation algorithms were used to predict the dose distributions. The dose from film and DOSXYZnrc were compared with the dose predicted by AAA and AcurosXB. RESULTS AAA overestimated the dose behind the rods by 15-25% and underestimated the dose laterally to the rods by 5-15% depending on the range of materials and energies investigated. AcurosXB overestimated the dose behind the rods by 1-18% and underestimated the dose laterally to the rods by up to 5% depending on the range of material and energies investigated. CONCLUSIONS AAA cannot deliver clinically acceptable dose calculation results at a distance less than 10 mm from metals, for a single field treatment. Acuros XB is able to handle metals of low atomic numbers (Z ≤ 26), but not tungsten (Z = 74). This can be due to the restriction of the CT-density table in EclipseTM TPS, which has an upper HU limit of 10501.

ORGAN ABSORBED DOSE ESTIMATION REFLECTING SPECIFIC ORGAN MASSES WITH SIMPLE SCALING OF REFERENCE DOSES USING THE ORGAN MASSES

2020 ◽  
Vol 189 (4) ◽  
pp. 489-496
Author(s):  
Kentaro Manabe ◽  
Shuji Koyama
Keyword(s):  
Absorbed Dose ◽  
Organ Dose ◽  
Wide Distribution ◽  
Organ Doses ◽  
Organ Mass ◽  
Red Marrow ◽  
Straightforward Method ◽  
Simple Scaling ◽  
Specific Organ ◽  
Reference Doses

Abstract Estimating organ absorbed doses in consideration of person-specific parameters is important for radiation protection in diagnostic nuclear medicine. This study proposes a straightforward method for estimating the organ dose that reflects a specific organ mass by scaling the reference organ dose using the inverse ratio of the specific organ mass to the reference organ mass. For the administration of radiopharmaceuticals labelled by 99mTc or 123I, the organ doses for the liver, spleen, red marrow and thyroid obtained by the method were compared with those generated by a Monte Carlo simulation. The discrepancies were less than 14% for the liver, spleen and thyroid. Conversely, in some cases, the red marrow discrepancies were greater than 30% due to the wide distribution of red marrow in the trunk and head regions. This study confirms that the method of scaling organ doses can be effective for estimating mass-specific doses for solid organs.

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