Read by QxMD icon Read

Monte carlo dose calculation

Carla Winterhalter, Gabriel Meier, David Oxley, Damien Charles Weber, Antony John Lomax, Sairos Safai
Patient specific quality assurance is crucial to guarantee safety in proton pencil beam scanning. In current clinical practice, this requires extensive, time consuming measurements. Additionally, these measurements do not consider the influence of density heterogeneities in the patient and are insensitive to delivery errors.
 In this work, we investigate the use of log file based Monte Carlo calculations for dose reconstructions in the patient CT, which takes the combined influence of calculational and delivery errors into account...
December 12, 2018: Physics in Medicine and Biology
Frank I Scott, F Reed Johnson, Meenakshi Bewtra, Colleen M Brensinger, Jason A Roy, Shelby D Reed, Mark T Osterman, Ronac Mamtani, Lang Chen, Huifeng Yun, Fenlong Xie, Jeffrey R Curtis, James D Lewis
Background: Corticosteroids (CS) and anti-TNF drugs are used to treat Crohn's disease (CD). In this study, we assessed the net health benefit of initiating anti-TNF therapy relative to additional CS use in CD using a novel combination of a retrospective cohort study and a simulation model. Methods: Using Medicaid data from 2001 to 2005 and Medicare data from 2006 to 2013, beneficiaries were identified with CD and CS use who subsequently received either an anti-TNF or reached a cumulative dose of >3000 mg CS during the year...
December 9, 2018: Inflammatory Bowel Diseases
Duong Thanh Tai, Luong Thi Oanh, Nguyen Dong Son, Truong Thi Hong Loan, James C L Chow
Aim: The aim of this study is to verify the Prowess Panther jaws-only intensity modulated radiation therapy (JO-IMRT) treatment planning (TP) by comparing the TP dose distributions for head-and-neck (H&N) cancer with the ones simulated by Monte Carlo (MC). Background: To date, dose distributions planned using JO-IMRT for H&N patients were found superior to the corresponding three-dimensional conformal radiotherapy (3D-CRT) plans. Dosimetry of the JO-IMRT plans were also experimentally verified using an ionization chamber, MapCHECK 2, and Octavius 4D and good agreements were shown...
January 2019: Reports of Practical Oncology and Radiotherapy
Jeffrey E Snyder, Daniel E Hyer, Ryan T Flynn, Amanda Boczkowski, Dongxu Wang
Accurate beam modeling is essential to help ensure overall accuracy in the radiotherapy process. This study describes our experience with beam model validation of a Monaco treatment planning system on a Versa HD linear accelerator. Data were collected such that Monaco beam models could be generated using three algorithms: collapsed cone (CC) and photon Monte Carlo (MC) for photon beams, and electron Monte Carlo (eMC) for electron beams. Validations are performed on measured percent depth doses (PDDs) and profiles, for open-field point-doses in homogenous and heterogeneous media, and for obliquely incident electron beams...
December 7, 2018: Journal of Applied Clinical Medical Physics
Pablo Botas, Jihun Kim, Brian A Winey, Harald Paganetti
To develop an online plan adaptation algorithm for intensity modulated proton therapy (IMPT) based on fast Monte Carlo dose calculation and cone beam CT (CBCT) imaging.
 Methods: A cohort of 10 head and neck cancer patients with an average of 6 CBCT scans were studied. To adapt the treatment plan to the new patient geometry, contours were propagated to the CBCTs with a vector field (VF) calculated with deformable image registration between the CT and the CBCTs. Within the adaptive planning algorithm, beamlets were shifted following the VF at their distal falloff and raytraced in the CBCT to adjust their energies, creating a geometrically adapted plan...
November 22, 2018: Physics in Medicine and Biology
Pan Ma, Yongbao Li, Yuan Tian, Bo Liu, Fugen Zhou, Jianrong Dai
Currently only flat dose distributions can be generated by electron beams of a linear accelerator for intraoperative radiotherapy. However, spherical dose distributions are more desirable for certain types of cancers such as breast cancer and brain cancers. In this study, we propose the design of a spherical applicator for delivery of spherical dose distributions. The spherical applicator consists of an upper cylindrical collimator to collimate the electron beam, a middle scattering foil to scatter the beam and a lower hollow sphere with a modulator to shape the beam and a spherical shell used to contain the modulator...
October 29, 2018: Physics in Medicine and Biology
James L Bedford
Over the last decade, dose calculations which solve the linear Boltzmann transport equations have been introduced into clinical practice and are now in widespread use. However, knowledge in the radiotherapy community concerning the details of their function is limited. This review gives a general description of the linear Boltzmann transport equations as applied to calculation of absorbed dose in clinical radiotherapy. The aim is to elucidate the principles of the method, rather than to describe a particular implementation...
November 14, 2018: Physics in Medicine and Biology
Sridhar Sahoo, Vandana Srivastava, T Palani Selvam, A K Bakshi, Rajesh Kumar, Rama Prajith, D Datta, Chinnaesakki S, S K Saxena, Yogendra Kumar, A Dash
This paper describes the evaluation of dosimetry characteristics of an in-house developed 177Lu skin patch source for treatment of non-melanoma skin cancer. A 177Lu skin patch source based on Nafion-115 membrane backbone containing 3.46 ± 0.01 mCi of activity was used. Activity measurement of the patch source was based on gamma ray spectrometry using a HPGe detector. The efficiencies of the HPGe detector were fitted using an orthogonal polynomial function. The absorbed dose rate to water at 5 µm depth in water was determined using an extrapolation chamber, EBT3 Gafchromic film and compared with Monte Carlo methods...
November 6, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
Toke Printz Ringbæk, Uli Weber, Alina Santiago, Gheorghe Iancu, Andrea Wittig, Leszek Grzanka, Niels Bassler, Rita Engenhart-Cabillic, Klemens Zink
A ripple filter (RiFi) is a passive energy modulator used in scanned particle therapy to broaden the Bragg peak, thus lowering the number of accelerator energies required for homogeneous target coverage, which significantly reduces the irradiation time. As we have previously shown, a new 6 mm thick RiFi with 2D groove shapes produced with 3D printing can be used in carbon ion treatments with a similar target coverage and only a marginally worse planning conformity compared to treatments with in-use 3 mm thick RiFis of an older 1D design...
November 2, 2018: Physics in Medicine and Biology
Louise Giansante, Juliana C Martins, Denise Y Nersissian, Karen C Kiers, Fernando U Kay, Marcio V Y Sawamura, Choonsik Lee, Eloisa M M S Gebrim, Paulo R Costa
PURPOSE: To evaluate organ doses in routine and low-dose chest computed tomography (CT) protocols using an experimental methodology. To compare experimental results with results obtained by the National Cancer Institute dosimetry system for CT (NCICT) organ dose calculator. To address the differences on organ dose measurements using tube current modulation (TCM) and fixed tube current protocols. METHODS: An experimental approach to evaluate organ doses in pediatric and adult anthropomorphic phantoms using thermoluminescent dosimeters (TLDs) was employed in this study...
December 3, 2018: Journal of Applied Clinical Medical Physics
Valerie D Nolt, Kyle D Pijut, Elizabeth B Autry, Whitney C Williams, David S Burgess, Donna R Burgess, Vaneet Arora, Robert J Kuhn
AIM: Pseudomonas aeruginosa (PsA) is a common pathogen in cystic fibrosis (CF). Management of an acute pulmonary exacerbation (APE) caused by PsA is dual anti-pseudomonal antibiotics, a beta-lactam plus aminoglycoside. Aminoglycoside dosing in CF differs from the general population due to altered pharmacokinetics. The primary objective of this study was to utilize pharmacokinetic data from adult CF patients that received amikacin to determine the probability of target attainment for APEs caused by PsA...
December 3, 2018: Pediatric Pulmonology
Marco Durante, Harald Paganetti, Arnold Pompos, Stephen F Kry, Xiaodong Wu, David R Grosshans
PURPOSE: To define the physical parameters needed to characterize a particle beam in order to allow inter-comparison of different experiments performed using different ions at the same facility and using the same ion at different facilities. METHODS: At the request of the National Cancer Institute (NCI), a special panel was convened to review the current status of the field and to provide suggested metrics for reporting the physical parameters of particle beams to be used for biological research...
December 3, 2018: Medical Physics
N Patrik Brodin, Rafi Kabarriti, Mark Pankuch, Clyde B Schechter, Vinai Gondi, Shalom Kalnicki, Chandan Guha, Madhur K Garg, Wolfgang A Tomé
PURPOSE: Developing a quantitative decision-support strategy estimating the impact of normal tissue complications from definitive radiation therapy (RT) for head and neck cancer (HNC). We developed this strategy to identify oropharyngeal HNC patients that may benefit most from receiving proton RT. METHODS AND MATERIALS: Recent normal tissue complication probability (NTCP) models for dysphagia, esophagitis, hypothyroidism, xerostomia and oral mucositis were used to estimate NTCP for 33 oropharyngeal HNC patients previously treated with photon IMRT...
November 26, 2018: International Journal of Radiation Oncology, Biology, Physics
D M Santos, K Wachowicz, B Burke, B G Fallone
PURPOSE: Real-time MR-guidance is of interest to various groups globally because of the superior soft-tissue contrast MR images offer over other X-ray based imaging modalities. Because of the precision required in proton therapy, proton therapy treatments rely heavily on image-guidance. Integrating an MRI into a proton therapy treatment is a challenge. The charged particles (protons) used in proton therapy experience magnetic forces when travelling through the MRI magnetic fields. Given that it is desired that proton beams can be delivered with sub-millimetre accuracy, it is important that all potential sources of beam displacement are well modeled and understood...
November 29, 2018: Medical Physics
Nolan Esplen, Eisa Alyaqoub, Magdalena Bazalova-Carter
PURPOSE: The goal of this work was to design a realistic mouse phantom as a useful tool for accurate dosimetry in radiobiology experiments. METHODS: A subcutaneous tumor-bearing mouse was scanned in a microCT scanner, its organs manually segmented and contoured. The resulting geometries were converted into a stereolithographic file format (STL) and sent to a multi-material 3D printer. The phantom was split into two parts to allow for lung excavation and 3D-printed with an acrylic-like material and consisted of the main body (mass density ρ=1...
November 29, 2018: Medical Physics
Ashutosh Sinha, Navin Singh, Bhanu Mani Dixit, Nirmal Kumar Painuly
Introduction: Most preclinical studies using radiopharmaceuticals have been carried out on mice. In nuclear medicine and radioimmunotherapy procedures, I131 and Y90 have been widely used. For better estimation of doses from these procedures, S value plays a vital role. In this study, we have evaluated S values for major source and target combinations of Digimouse voxel phantom. Materials and Methods: We have used the Digimouse voxel phantom which was incorporated in Monte Carlo code FLUKA...
October 2018: Journal of Cancer Research and Therapeutics
José Ramos-Méndez, Lucas N Burigo, Reinhard Schulte, Cynthia Chuang, Bruce Faddegon
Details of the pattern of ionization formed by particle tracks extends knowledge of dose effects on the nanometer scale. Ionization detail (ID), frequently characterized by ionization cluster size distributions (ICSD), is obtained through time-consuming Monte Carlo (MC) track-structure simulations. In this work, TOPAS-nBio was used to generate a highly precise database of biologically significant ID quantities, sampled with randomly oriented 2.3 nm diameter cylinders, 3.4 nm (10 base pairs) long, inside a chromatin-size cylinder, irradiated by 1-1000 MeV/u ions of Z  =  1-8...
November 28, 2018: Physics in Medicine and Biology
Mariana Bobeica, Sohichiroh Aogaki, Theodor Asavei, Mihail O Cernaianu, Petru Ghenuche, Dan Stutman
One of the specific properties of laser-driven radiation is a broadband energy spectrum, which is also a feature of the space radiation fields. This property can be used in materials science studies or radiobiology experiments to simulate the energy spectrum of space radiation exposures in a ground-based laboratory. However, the differences in effects between the higher dose rates of laser generated radiation and the lower dose rates of space radiation have to be investigated in separate, prior studies. A design for a high-throughput irradiation experiment and the associated Monte Carlo dose calculations for a broadband energy proton beam depositing energy in a cell monolayer is presented...
November 2018: Life Sciences in Space Research
H Yoshitomi, M Kowatari, M Hagiwara, S Nagaguro, H Nakamura
To manage the equivalent doses for radiation workers, exposure inhomogeneity is an important factor in the decision-making process related to protection measures and additional monitoring. Our previous study proposed the methodology to evaluate the inhomogeneity of exposure quantitatively. In this study, we applied proposed method to five different types of actual exposure situations encountered in the nuclear industry. Two of them were conventionally characterized as homogeneous exposure, and the other three were conventionally characterized as inhomogeneous exposure...
November 23, 2018: Radiation Protection Dosimetry
Thomas Henry, Jakob Ödén
PURPOSE: Interlaced beams have previously been proposed for delivering proton grid therapy. This study aims to assess dose-averaged LET (LETd ) and RBE-weighted dose (DRBE ) distributions of such beam geometries, and compare them with conventional intensity modulated proton therapy (IMPT). METHODS: IMPT plans and four different interlaced proton grid therapy plans were generated for five patient cases (esophagus, lung, liver, prostate, anus). The constant RBE = 1...
November 22, 2018: Physica Medica: PM
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"