A CT‐based Monte Carlo simulation tool for dosimetry planning and analysis

DeMarco, John J.; Solberg, Timothy D.; Smathers, James B.

doi:10.1118/1.598167

Cited by 188 publications

(141 citation statements)

References 30 publications

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“…The voxels in the gestational sac were modeled as water, and the voxels in the uterus were modeled as soft tissue. Each voxel of the mother outside these fetal regions was modeled as one of six tissue types (lung, fat, water, muscle, bone, or air) (13). The process of creating voxelized models from the original patient images is illustrated in Figure 3.…”

Section: Patient Modelsmentioning

confidence: 99%

Radiation Dose to the Fetus for Pregnant Patients Undergoing Multidetector CT Imaging: Monte Carlo Simulations Estimating Fetal Dose for a Range of Gestational Age and Patient Size

Angel¹,

Wellnitz²,

Goodsitt³

et al. 2008

Radiology

131

135

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Purpose:To use Monte Carlo simulations of a current-technology multidetector computed tomographic (CT) scanner to investigate fetal radiation dose resulting from an abdominal and pelvic examination for a range of actual patient anatomies that include variation in gestational age and maternal size. Materials and Methods:Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Twenty-four models of maternal and fetal anatomy were created from image data from pregnant patients who had previously undergone clinically indicated CT examination. Gestational age ranged from less than 5 weeks to 36 weeks. Simulated helical scans of the abdominal and pelvic region were performed, and a normalized dose (in milligrays per 100 mAs) was calculated for each fetus. Stepwise multiple linear regression was performed to analyze the correlation of dose with gestational age and anatomic measurements of maternal size and fetal location. Results were compared with several existing fetal dose estimation methods. Results:Normalized fetal dose estimates from the Monte Carlo simulations ranged from 7.3 to 14.3 mGy/100 mAs, with an average of 10.8 mGy/100 mAs. Previous methods yielded values of 10 -14 mGy/100 mAs. The correlation between gestational age and fetal dose was not significant (P ϭ .543). Normalized fetal dose decreased linearly with increasing patient perimeter (R 2 ϭ 0.681, P Ͻ .001), and a two-factor model with patient perimeter and fetal depth demonstrated a strong correlation with fetal dose (R 2 ϭ 0.799, P Ͻ .002). Conclusion:A method for the estimation of fetal dose from models of actual patient anatomy that represented a range of gestational age and patient size was developed. Fetal dose correlated with maternal perimeter and varied more than previously recognized. This correlation improves when maternal size and fetal depth are combined. Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, use the Radiology Reprints form at the end of this article. D iagnostic computed tomographic(CT) imaging is sometimes necessary in a pregnant patient. When a radiologist needs to decide if the diagnostic benefits will outweigh the risks of radiation, it is important to have a reasonably accurate estimate of the radiation dose that the conceptus (fetus or embryo) will receive. Furthermore, in cases in which pregnancy is discovered during or after CT examination, the patient and/or physician may request an estimate of the radiation dose received by the conceptus. For the remainder of this article, the term fetus will be used to refer to either an embryo or a fetus and will therefore be used to describe a conceptus at any gestational age.It is not known definitively how much radiation dose a fetus receives during CT examination, because this cannot be measured directly. Some methods to estimate fetal dose exist, but these estimates are limited by their simplifying assumptions. Existing fetal dose estimation m...

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Section: Patient Modelsmentioning

confidence: 99%

Radiation Dose to the Fetus for Pregnant Patients Undergoing Multidetector CT Imaging: Monte Carlo Simulations Estimating Fetal Dose for a Range of Gestational Age and Patient Size

Angel¹,

Wellnitz²,

Goodsitt³

et al. 2008

Radiology

131

135

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“…Different versions of MCNP are additional useful tools for radiotherapy dosimetry. MCNP4A was used by DeMarco et al ( 12 ) for radiotherapy dose calculations, while Lewis et al ( 13 ) and Kim et al ( 14 ) used MCNP4B and Aaronson et al ( 15 ) used MCNP4C for this purpose.…”

Section: Introductionmentioning

confidence: 99%

Suggesting a new design for multileaf collimator leaves based on Monte Carlo simulation of two commercial systems

Hariri

Shahriari

2010

J Applied Clin Med Phys

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Due to intensive use of multileaf collimators (MLCs) in clinics, finding an optimum design for the leaves becomes essential. There are several studies which deal with comparison of MLC systems, but there is no article with a focus on offering an optimum design using accurate methods like Monte Carlo. In this study, we describe some characteristics of MLC systems including the leaf tip transmission, beam hardening, leakage radiation and penumbra width for Varian and Elekta 80‐leaf MLCs using MCNP4C code. The complex geometry of leaves in these two common MLC systems was simulated. It was assumed that all of the MLC systems were mounted on a Varian accelerator and with a similar thickness as Varian's and the same distance from the source. Considering the obtained results from Varian and Elekta leaf designs, an optimum design was suggested combining the advantages of three common MLC systems and the simulation results of this proposed one were compared with the Varian and the Elekta. The leakage from suggested design is 29.7% and 31.5% of the Varian and Elekta MLCs. In addition, other calculated parameters of the proposed MLC leaf design were better than those two commercial ones. Although it shows a wider penumbra in comparison with Varian and Elekta MLCs, taking into account the curved motion path of the leaves, providing a double focusing design will solve the problem. The suggested leaf design is a combination of advantages from three common vendors (Varian, Elekta and Siemens) which can show better results than each one. Using the results of this theoretical study may bring about superior practical outcomes.PACS number: 87.56.nk, 87.55.K, 87.56.N

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“…By default, MCNP_GUI converts each HU into one of seventeen material-density combination using a lookup table as described by DeMarco et al and recreated in Table 1 [3]. Additionally, the user can select conversion tables based on the subject of the scan (e.g.…”

Section: Materials Conversionmentioning

confidence: 99%

“…In order to automate the basic functions required to create a voxelized patient model from a CT dataset for use with the Los Alamos Monte Carlo N-Particle (MCNP) program, DeMarco et al developed the "RTMCNP Preprocessor" [1][2][3].…”

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confidence: 99%

Improved CT-based voxel phantom generation for MCNP Monte Carlo

Speiser

DeMarco

2014

Progress in Nuclear Science and Technology

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A graphic user interface has been developed to perform the basic and advanced functions required to create CT-based, voxelized patent models for MCNP and MCNPX Monte Carlo simulations. Additional flexibility is enabled in selective tally definition, lattice structure limits, and conversion of CT number to materials. Setting lattice structure limits can reduce or obviate the need for excessive sub-sampling and improve efficiency while preserving model resolution. The patient model, tally definition, and subsequent simulation output are all incorporated in a post-processing routine that enables comparative analysis between calculated and measured datasets. Judicious application of these developments can greatly decrease the time required to achieve a given uncertainty while preserving model detail; use of these tools typically results in reduction of simulation times by over 60%.

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A CT‐based Monte Carlo simulation tool for dosimetry planning and analysis

Cited by 188 publications

References 30 publications

Radiation Dose to the Fetus for Pregnant Patients Undergoing Multidetector CT Imaging: Monte Carlo Simulations Estimating Fetal Dose for a Range of Gestational Age and Patient Size

Radiation Dose to the Fetus for Pregnant Patients Undergoing Multidetector CT Imaging: Monte Carlo Simulations Estimating Fetal Dose for a Range of Gestational Age and Patient Size

Suggesting a new design for multileaf collimator leaves based on Monte Carlo simulation of two commercial systems

Improved CT-based voxel phantom generation for MCNP Monte Carlo

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