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Monte carlo dose calculation

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https://www.readbyqxmd.com/read/30106343/target-size-variation-in-microdosimetric-distributions-and-its-impact-on-the-linear-quadratic-parameterization-of-cell-survival
#1
Fernanda Villegas, Nina Tilly, Anders Ahnesjö
The linear-quadratic (LQ) parameterization of survival fraction [SF( D)] inherently assumes that all cells in a population receive the same dose ( D), albeit the distribution of specific energy z over the individual cells f( z, D) can be very wide. From these microdosimetric distributions, which are target size dependent, we estimate the size of the cellular sensitive volume by analyzing its influence on the LQ parameterization of cell survival. A Monte Carlo track structure code was used to simulate detailed tracks from a 60 Co source as well as proton and carbon ions of various energies...
August 14, 2018: Radiation Research
https://www.readbyqxmd.com/read/30105825/risk-of-developing-radiogenic-cancer-following-photon-beam-radiotherapy-for-graves-orbitopathy
#2
Michalis Mazonakis, Antonis Tzedakis, Efrossyni Lyraraki, John Damilakis
PURPOSE: The objective of this study was to estimate the probability for cancer development due to radiotherapy for Graves' orbitopathy with 6 MV X-rays. METHODS: Orbital irradiation was simulated with the MCNP code. The radiation dose received by ten out-of-field organs having a strong disposition for carcinogenesis was calculated with Monte Carlo methods. These dose calculations were used to estimate the organ-dependent lifetime attributable risk (LAR) for cancer induction in 30- and 50-year-old males and females on the basis of the linear model suggested by the BEIR-VII report...
August 14, 2018: Medical Physics
https://www.readbyqxmd.com/read/30101751/ionization-chamber-dosimetry-based-on-sup-60-sup-co-absorbed-dose-to-water-calibration-for-diagnostic-kilovoltage-x-ray-beams
#3
Fujio Araki, Takeshi Ohno, Suzuna Umeno
The purpose of this study was to develop a new ionization chamber dosimetry formalism for diagnostic kilovoltage x-ray beams based on a 60Co absorbed dose-to-water calibration coefficient . To validate the new chamber dosimetry, 39 fluence spectra of kilovoltage x-rays were calculated, using a SpekCalc program, for Al half-value-layer (Al-HVL) values of 1.4 8.5 mm and tube voltages of 50 137.6 kVp. We used these spectra to calculate the beam quality conversion factor for kilovoltage x-ray beams Qx to a 60Co beam for a PTW 30013 Farmer ionization chamber in a reference geometrical setup (depth = 1 cm in water, field size = 20 × 20 cm2)...
August 13, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30101560/feasibility-and-accuracy-of-uf-nci-phantoms-and-monte-carlo-retrospective-dosimetry-in-children-treated-on-national-wilms-tumor-study-protocols
#4
John A Kalapurakal, Mahesh Gopalakrishnan, Matthew Mille, Irene Helenowski, Susan Peterson, Cynthia Rigsby, Fran Laurie, Jae Won Jung, Thomas J Fitzgerald, Choonsik Lee
PURPOSE: This pilot study was done to determine the feasibility and accuracy of University of Florida/National Cancer Institute (UF/NCI) phantoms and Monte Carlo (MC) retrospective dosimetry and had two aims: (1) to determine the anatomic accuracy of UF/NCI phantoms by comparing 3D organ doses in National Wilms Tumor Study (NWTS) patient-matched UF/NCI phantoms to organ doses in corresponding patient-matched CT scans and (2) to compare infield and out-of-field organ dosimetry using two dosimetry methods-standard radiation therapy (RT) treatment planning systems (TPS) and MC dosimetry in these two anatomic models...
August 12, 2018: Pediatric Blood & Cancer
https://www.readbyqxmd.com/read/30095077/rapidbrachymctps-a-monte-carlo-based-treatment-planning-system-for-brachytherapy-applications
#5
Gabriel Famulari, Marc-André Renaud, Christopher M Poole, Michael D C Evans, Jan Seuntjens, Shirin A Enger
Despite being considered the gold standard for brachytherapy dosimetry, Monte Carlo (MC) has yet to be implemented into a software for brachytherapy treatment planning. The purpose of this work is to present RapidBrachyMCTPS, a novel treatment planning system (TPS) for brachytherapy applications equipped with a graphical user interface (GUI), optimization tools and a Geant4-based MC dose calculation engine, RapidBrachyMC. Brachytherapy sources and applicators were implemented in RapidBrachyMC and made available to the user via a source and applicator library in the GUI...
August 10, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30093860/optimal-regimens-and-cutoff-evaluation-of-tildipirosin-against-pasteurella-multocida
#6
Zhixin Lei, Qianying Liu, Yi Qi, Bing Yang, Haseeb Khaliq, Jincheng Xiong, Gopi Krishna Moku, Saeed Ahmed, Kun Li, Hui Zhang, Wenqiu Zhang, Jiyue Cao, Qigai He
Pasteurella multocida (PM) can invade the upper respiratory tract of the body and cause death and high morbidity. Tildipirosin, a new 16-membered-ring macrolide antimicrobial, has been recommended for the treatment of respiratory diseases. The objective of this research was to improve the dose regimes of tildipirosin to PM for reducing the macrolides resistance development with the pharmacokinetic/pharmacodynamic (PK/PD) modeling approach and to establish an alternate cutoff for tildipirosin against PM. A single dose (4 mg/kg body weight) of tildipirosin was administered via intramuscular (i...
2018: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/30087007/the-exploration-of-population-pharmacokinetic-model-for-meropenem-in-augmented-renal-clearance-and-investigation-of-optimum-setting-of-dose
#7
Tatsuro Tamatsukuri, Masayuki Ohbayashi, Noriko Kohyama, Yasuna Kobayashi, Toshinori Yamamoto, Kenichiro Fukuda, Shunsuke Nakamura, Yasufumi Miyake, Kenji Dohi, Mari Kogo
In recent years, augmented renal clearance (ARC), in which renal function is excessively enhanced, has been reported, and its influence on β-lactam antibiotics has been investigated. In this study, we aimed to determine the optimum population pharmacokinetic model of meropenem in patients with sepsis with ARC, and evaluated dosing regimens based on renal function. Seventeen subjects (6 with ARC and 11 without) were enrolled in this study. Predicted meropenem concentrations were evaluated for bias and precision using the Bland-Altman method...
August 4, 2018: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
https://www.readbyqxmd.com/read/30079474/dosimetric-comparison-of-pencil-beam-and-monte-carlo-algorithms-in-conformal-lung-radiotherapy
#8
Yelda Elcim, Bahar Dirican, Omer Yavas
PURPOSE: In this study, lung radiotherapy target volumes as well as critical organs such as the lungs, spinal cord, esophagus, and heart doses calculated using pencil beam (PB) and Monte Carlo (MC) algorithm-based treatment planning systems (TPSs) were compared. The main aim was the evaluation of calculated dose differences between the PB and MC algorithms in a highly heterogeneous medium. METHODS: A total of 6 MV photon energy conformal treatment plans were created for a RANDO lung phantom using one PB algorithm-based Precise Plan Release 2...
August 5, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30076424/dramatic-dose-reduction-in-three-dimensional-rotational-angiography-after-implementation-of-a-simple-dose-reduction-protocol
#9
Savine C S Minderhoud, Femke van der Stelt, Mirella M C Molenschot, Michel S Koster, Gregor J Krings, Johannes M P J Breur
Previously, median effective dose (ED) of 1.6 mSv per three-dimensional rotational angiography (3DRA) has been reported. This study evaluated ED and image quality in 3DRA after implementation of a simple dose reduction protocol in pediatric catheterizations. Simple conversion factors between 3DRA ED and readily available parameters at the cathlab were determined. The dose reduction protocol consisted of frame reduction (60-30 frames/s (f/s)), active collimation of the X-ray beam, usage of a readily available low dosage program, and a pre-3DRA run check...
August 3, 2018: Pediatric Cardiology
https://www.readbyqxmd.com/read/30075771/estimated-radiation-risk-of-cancer-from-dental-cone-beam-computed-tomography-imaging-in-orthodontics-patients
#10
Jih-Kuei Yeh, Chia-Hui Chen
BACKGROUND: Radiation dose evaluation is important to cone-beam computed tomography (CBCT) for routine orthodontic treatment planning, especially for a significant proportion of children in orthodontic patients. This study evaluated the patient radiation dose and estimated the radiation cancer risk on dental CBCT according to the calculations by the Monte Carlo simulation method. METHODS: The dental CBCT scanner evaluated in this project was the i- CAT® (Imaging Sciences International Inc...
August 3, 2018: BMC Oral Health
https://www.readbyqxmd.com/read/30058170/validation-and-clinical-implementation-of-an-accurate-monte-carlo-code-for-pencil-beam-scanning-proton-therapy
#11
Sheng Huang, Minglei Kang, Kevin Souris, Christopher Ainsley, Timothy D Solberg, James E McDonough, Charles B Simone, Liyong Lin
Monte Carlo (MC)-based dose calculations are generally superior to analytical dose calculations (ADC) in modeling the dose distribution for proton pencil beam scanning (PBS) treatments. The purpose of this paper is to present a methodology for commissioning and validating an accurate MC code for PBS utilizing a parameterized source model, including an implementation of a range shifter, that can independently check the ADC in commercial treatment planning system (TPS) and fast Monte Carlo dose calculation in opensource platform (MCsquare)...
July 30, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30055661/clinical-evaluation-for-the-difference-of-absorbed-doses-calculated-to-medium-and-calculated-to-water-by-monte-carlo-method
#12
Li Chen, Botian Huang, Xiaoyan Huang, Wufei Cao, Wenzhao Sun, Xiaowu Deng
BACKGROUND: To evaluate the difference of absorbed doses calculated to medium and to water by a Monte Carlo (MC) algorithm based treatment planning system (TPS), and to assess the potential clinical impact to dose prescription. METHODS: Thirty patients, 10 nasopharyngeal cancer (NPC), 10 lung cancer and 10 bone metastases cases, were selected for this study. For each case, the treatment plan was generated using a commercial MC based TPS and dose was calculated to medium (Dm )...
July 28, 2018: Radiation Oncology
https://www.readbyqxmd.com/read/30053277/a-comparison-of-beta-skin-doses-calculated-with-varskin-5-35-3-and-mcnp5
#13
J Dubeau, S S Hakmana Witharana, J Sun, B E Heinmiller, W J Chase
The computer code VARSKIN, version 5.3, is widely used to calculate superficial dose caused by the routine handling of radioactive substances or in skin contamination incidents. It allows a variety of source configurations, points, volume, surface and syringe-like (cylindrical) and a variety of exposure situations such as direct skin contact or exposure through clothing. However, there is a need for more benchmarking data of VARSKIN, especially for beta particles, with complex irradiation geometries. Dose calculations using MCNP5 and VARSKIN 5...
July 25, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30045112/total-ambient-dose-equivalent-buildup-factors-for-portland-concrete
#14
Paulina Duckic, Robert Bruce Hayes
In this work, total ambient dose equivalent buildup factors for Portland concrete slabs are calculated using Monte Carlo n-particle software MCNP6™. Buildup factor calculations could approach intractable solutions in general as they depend on a large number of variables. These include geometry, source energy, and the composition of the shield (which itself can be heterogeneous). In this work, Cf and americium-beryllium sources are considered, as well as monoenergetic incident neutrons in the energy range from 0...
September 2018: Health Physics
https://www.readbyqxmd.com/read/30043980/evaluation-of-the-4d-radpos-dosimetry-system-for-dose-and-position-quality-assurance-of-cyberknife
#15
Raanan Marants, Eric Vandervoort, Joanna E Cygler
PURPOSE: The Synchrony respiratory motion tracking of the CyberKnife system purports to provide real-time tumor motion compensation during robotic radiosurgery. Such a complex delivery system requires thorough quality assurance. In this work, RADPOS applicability as a dose and position quality assurance tool for CyberKnife treatments is assessed quantitatively for different phantom types and breathing motions which increase in complexity to more closely resemble clinical situations. METHODS: Two radiotherapy treatment experiments were performed where dose and position were measured with the RADPOS probe housed within a Solid Water phantom...
July 25, 2018: Medical Physics
https://www.readbyqxmd.com/read/30033938/a-full-scale-clinical-prototype-for-proton-range-verification-using-prompt-gamma-ray-spectroscopy
#16
Fernando Hueso-González, Moritz Rabe, Thomas Ruggieri, Thomas Bortfeld, Joost M Verburg
We present a full-scale clinical prototype system for in vivo range verification of proton pencil-beams using the prompt gamma-ray spectroscopy method. The detection system consists of eight LaBr3 scintillators and a tungsten collimator, mounted on a rotating frame. Custom electronics and calibration algorithms have been developed for the measurement of energy- and time-resolved gamma-ray spectra during proton irradiation at a clinical dose rate. Using experimentally determined nuclear reaction cross sections and a GPU-accelerated Monte Carlo simulation, a detailed model of the expected gamma-ray emissions is created for each individual pencil-beam...
July 23, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30032259/validation-of-monte-carlo-dose-calculation-for-paediatric-ct-examinations-using-tube-current-modulation-based-on-in-phantom-dosimetry
#17
K Fujii, K Nomura, Y Muramatsu, S Obara, T Goto, K Akahane, H Ota, S Tsukagoshi, M Kusumoto
The aim of this study is to estimate tube current modulation (TCM) profiles in paediatric computed tomography (CT) examinations with a TCM scheme (Volume-EC) and evaluate the estimation accuracy of TCM profiles. Another aim is to validate organ doses calculated using Monte Carlo-based CT dosimetry software and estimated TCM profiles by comparing them with those measured using 5-year-old and 10-year-old anthropomorphic phantoms and radio-photoluminescence glass dosemeters. Dose calculations were performed by inputting detailed descriptions of a CT scanner, scan parameters and CT images of the phantoms into the software...
July 19, 2018: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/30022768/re-evaluation-of-pediatric-sup-18-sup-f-fdg-dosimetry-cristy-eckerman-versus-uf-nci-hybrid-computational-phantoms
#18
Kitiwat Khamwan, Shannon E O'Reilly, Donika Plyku, Alison Goodkind, Anders Josefsson, Xinhua Cao, Frederic H Fahey, S Ted Treves, Wesley E Bolch, George Sgouros
Because of the concerns associated with radiation exposure at a young age, there is an increased interest in pediatric dose estimates for imaging agents. Almost all reported pediatric absorbed dose estimates, however, have been determined using adult pharmacokinetic data with S values that take into account the anatomical differences between adults and children based upon the older Cristy-Eckerman (C-E) stylized phantoms. In this work, we use pediatric model-derived pharmacokinetics to compare absorbed dose and effective dose estimates for 18F-FDG in pediatric patients using S values generated from two different geometries of the computational phantom...
July 19, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30019693/influence-of-the-spect-calibration-source-position-on-the-absorbed-dose-calculation-for-sup-131-sup-i-nai-therapy-using-gate-simulations
#19
Samira Marques de Carvalho, Ana Paula Marques Costa, Celso D Ramos, João H M Castelo, Sérgio Querino Brunetto, D A B Bonifacio
Many research groups have studied nuclear medicine image quantification to improve its accuracy in dose estimation. This work aims to evaluate the influence of the source calibration position for absorbed dose calculation for a 131I-NaI therapy using Monte Carlo (MC) simulations. The calibration approach consisted of a cylindrical phantom filled with water. A cylindrical 131I source with 361.1 3.6 kBq/mL was positioned at the center of the phantom and its outer part. Images were acquired with 15,000 counts per projection image acquired with SPECT detector (High Counts Density - HCD) and 3,000 counts per projection (Low Counts Density - LCD)...
July 18, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
https://www.readbyqxmd.com/read/30019423/a-robust-intensity-modulated-proton-therapy-optimizer-based-on-monte-carlo-dose-calculation
#20
Jiasen Ma, Hok Seum Wan Chan Tseung, Michael G Herman, Chris Beltran
PURPOSE: Accuracy of dose calculation models and robustness under various uncertainties are key factors influencing the quality of intensity modulated proton therapy (IMPT) plans. To mitigate the effects of uncertainties and to improve the dose calculation accuracy, an all-scenario robust IMPT optimization based on accurate Monte Carlo (MC) dose calculation was developed. METHODS: In the all-scenario robust IMPT optimization, dose volume histograms (DVHs) were computed for the nominal case and for each uncertainty scenario...
July 18, 2018: Medical Physics
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