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Title: SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

Abstract

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients ofmore » stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)« less

Authors:
 [1];  [2]; ;  [1]; ;  [3]
  1. Institute of Radiation Medicine Fudan University, Shanghai (China)
  2. (China)
  3. Shanghai General Hospital, Shanghai, Shanghai (China)
Publication Date:
OSTI Identifier:
22624411
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; ABDOMEN; ANIMAL TISSUES; CHEST; CHILDREN; COMPUTERIZED SIMULATION; COMPUTERIZED TOMOGRAPHY; CONVERSION; IMAGES; INTESTINES; LIVER; LUNGS; MONTE CARLO METHOD; PANCREAS; PEDIATRICS; PHANTOMS; RADIATION DOSES; RADIATION PROTECTION; SKIN; STOMACH

Citation Formats

Liu, Q, Shanghai General Hospital, Shanghai, Shanghai, Zhuo, W, Liu, H, Liu, Y, and Chen, T. SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms. United States: N. p., 2016. Web. doi:10.1118/1.4955667.
Liu, Q, Shanghai General Hospital, Shanghai, Shanghai, Zhuo, W, Liu, H, Liu, Y, & Chen, T. SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms. United States. doi:10.1118/1.4955667.
Liu, Q, Shanghai General Hospital, Shanghai, Shanghai, Zhuo, W, Liu, H, Liu, Y, and Chen, T. 2016. "SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms". United States. doi:10.1118/1.4955667.
@article{osti_22624411,
title = {SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms},
author = {Liu, Q and Shanghai General Hospital, Shanghai, Shanghai and Zhuo, W and Liu, H and Liu, Y and Chen, T},
abstractNote = {Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)},
doi = {10.1118/1.4955667},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • As part of a broader effort to calculate effective dose rate coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, soil or water, age-specific stylized phantoms have been employed to determine dose coefficients relating dose rate to organs and tissues in the body. In this article, dose rate coefficients computed using the International Commission on Radiological Protection reference adult male voxel phantom are compared with values computed using the Oak Ridge National Laboratory adult male stylized phantom in an air submersion exposure geometry. Monte Carlo calculations for both phantoms were performed for monoenergetic source photonsmore » in the range of 30 keV to 5 MeV. Furthermore, these calculations largely result in differences under 10 % for photon energies above 50 keV, and it can be expected that both models show comparable results for the environmental sources of radionuclides.« less
  • Dose rate coefficients computed using the International Commission on Radiological Protection (ICRP) reference adult female voxel phantom were compared with values computed using the Oak Ridge National Laboratory (ORNL) adult female stylized phantom in an air submersion exposure geometry. This is a continuation of previous work comparing monoenergetic organ dose rate coefficients for the male adult phantoms. With both the male and female data computed, effective dose rate as defined by ICRP Publication 103 was compared for both phantoms. Organ dose rate coefficients for the female phantom and ratios of organ dose rates for the voxel and stylized phantoms aremore » provided in the energy range from 30 to 5 MeV. Analysis of the contribution of the organs to effective dose is also provided. Lastly, comparison of effective dose rates between the voxel and stylized phantoms was within 8% at 100 keV and is <5% between 200 and 5000 keV.« less
  • Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to studymore » the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode. Regarding the BSF, the results achieved may lead to a MGD correction of about 6%, contributing to the improvement of the current guidelines used in these applications. Finally, considering the MC results obtained for the organ dose study, the radiation doses found for the tissues of the body other than the breast were in the range of tens of μSv, and are in part comparable to the ones obtained in standard DM. Nevertheless, in a single DBT examination, some organs (such as lung and thyroid) receive higher doses (of about 9% and 21%, respectively) with respect to the CC DM acquisition. Conclusions: Taking into account an average breast with a thickness of 4.5 cm, the MGDs for DM and DBT acquisitions were below the achievable value (2.0 mGy) defined by the European protocol. Additionally, in the case of a fusion imaging study (DM + DBT), the MGD for a 4.5 cm thick breast is of the order of 1.88 ± 0.36 mGy. Finally, organ dose evaluations underline the need to improve awareness concerning dose estimation of DBT exams for some organs, especially when radiation risk is assessed by using the effective dose.« less
  • Through an internally funded project at Oak Ridge National Laboratory, a high-resolution phantom was developed based on the National Library of Medicine`s Visible Human Data. Special software was written using the interactive data language (IDL) visualization language to automatically segment and classify some of the organs and the skeleton of the Visible Male. A high definition phantom consisting of nine hundred 512 x 512 slices was constructed of the entire torso. Computed tomography (CT) images of a patient`s tumor near the spine were scaled and morphed into the phantom model to create a patient-specific phantom. Calculations of dose to themore » tumor and surrounding tissue were then performed using the patient-specific phantom.« less
  • Purpose: ImpactMC (CT Imaging, Erlangen, Germany) is a Monte Carlo (MC) software package that offers a GPU enabled, user definable and validated method for 3D dose distribution calculations for radiography and Computed Tomography (CT). ImpactMC, in and of itself, offers limited capabilities to perform batch simulations. The aim of this work was to develop a framework for the batch simulation of absorbed organ dose distributions from CT scans of computational voxel phantoms. Methods: The ICRP 110 adult Reference Male and Reference Female computational voxel phantoms were formatted into compatible input volumes for MC simulations. A Matlab (The MathWorks Inc., Natick,more » MA) script was written to loop through a user defined set of simulation parameters and 1) generate input files required for the simulation, 2) start the MC simulation, 3) segment the absorbed dose for organs in the simulated dose volume and 4) transfer the organ doses to a database. A demonstration of the framework is made where the glandular breast dose to the adult Reference Female phantom, for a typical Chest CT examination, is investigated. Results: A batch of 48 contiguous simulations was performed with variations in the total collimation and spiral pitch. The demonstration of the framework showed that the glandular dose to the right and left breast will vary depending on the start angle of rotation, total collimation and spiral pitch. Conclusion: The developed framework provides a robust and efficient approach to performing a large number of user defined MC simulations with computational voxel phantoms in CT (minimal user interaction). The resulting organ doses from each simulation can be accessed through a database which greatly increases the ease of analyzing the resulting organ doses. The framework developed in this work provides a valuable resource when investigating different dose optimization strategies in CT.« less