Abstract：
PURPOSE:To propose a method to calculate the tissue phantom ratio (TPR) using the depth dose and to compare the proposed method with two other methods. METHODS:An analytical dose model from Bjärngard was used to describe the depth dose and the TPR. The parameters of the model were derived from depth dose measurements, which were then used to calculate the TPR. The calculated TPR values were compared with actual measurements as well as with TPR values predicted from two methods that also use depth dose, namely, the method proposed by BrainLAB and the conventional method that sets the quotients of the scatter phantom ratios (Sp) to 1. RESULTS:TPR values calculated from the proposed algorithm deviated by -0.2 +/- 0.1% (mean deviation) from the experimental measurements, over a range of field sizes and depths. CONCLUSIONS:The results of the proposed method were in better agreement with the experimental measurements than were results using the other two methods. Furthermore, the differences between the proposed method and the other methods are statistically significant.
journal_name
Med Physjournal_title
Medical physicsauthors
Ramos Garcia LI,Almansa JFdoi
10.1118/1.3570575subject
Has Abstractpub_date
2011-05-01 00:00:00pages
2359-65issue
5eissn
0094-2405issn
2473-4209journal_volume
38pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:Reconstruction of electron spectra of medical accelerators from measured depth dose distributions is an attractive tool for commissioning of a Monte Carlo treatment planning system. However, the reconstruction method is an inverse radiation transport problem which is poorly conditioned, in the sense it may become unst...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1461840
更新日期：2002-04-01 00:00:00
abstract：:Nuclear Magnetic Resonance (NMR) permits the noninvasive measurement of blood flow signals unimpaired by clothes, bandages, casts, etc. The cylindrical crossed-coil NMR blood flowmeter was used to measure blood flow through a cross-section of the human forearm. Two calibration procedures are described: one for pulsati...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594989
更新日期：1981-07-01 00:00:00
abstract：:Different methods exist to determine the air kerma calibration factor of an ionization chamber for the spectrum of a 192Ir high-dose-rate (HDR) or pulsed-dose-rate (PDR) source. An analysis of two methods to obtain such a calibration factor was performed: (i) the method recommended by [Goetsch et al., Med. Phys. 18, 4...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1791352
更新日期：2004-10-01 00:00:00
abstract：PURPOSE:To introduce video surface imaging guidance in synchronization with 4D cone-beam CT (CBCT) scans, and in combination with respiration- gated or target-tracked dose delivery to treat mobile tumors, without collaterally damaging nearby critical structures. METHODS:The approach uses the concept that the integral ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734688
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Because the small-radius photon beams shaped by cones in stereotactic radiosurgery (SRS) lack lateral electronic equilibrium and a detector's finite cross section, direct experimental measurement of dosimetric data for these beams can be subject to large uncertainties. As the dose calculation accuracy of a trea...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3488900
更新日期：2010-10-01 00:00:00
abstract：PURPOSE:The Small Animal Radiation Research Platform (SARRP) has been developed for conformal microirradiation with on-board cone beam CT (CBCT) guidance. The graphics processing unit (GPU)-accelerated Superposition-Convolution (SC) method for dose computation has been integrated into the treatment planning system (TPS...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12862
更新日期：2018-05-01 00:00:00
abstract：PURPOSE:A preobject grid can reduce and correct scatter in cone beam computed tomography (CBCT). However, half of the signal in each projection is blocked by the grid. A synchronized moving grid (SMOG) has been proposed to acquire two complimentary projections at each gantry position and merge them into one complete pr...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4937934
更新日期：2016-01-01 00:00:00
abstract：PURPOSE:To develop a pencil beam dose calculation algorithm for scanned proton beams that improves modeling of scatter events. METHODS:Our pencil beam algorithm (PBA) was developed for calculating dose from monoenergetic, parallel proton beams in homogeneous media. Fermi-Eyges theory was implemented for pencil beam tr...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735624
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:The primary objective of this work is to measure the secondary neutron field produced by an uncollimated proton pencil beam impinging on different tissue-equivalent phantom materials using organic scintillation detectors. Additionally, the Monte Carlo code mcnpx-PoliMi was used to simulate the detector response...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4963813
更新日期：2016-11-01 00:00:00
abstract：PURPOSE:With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) IMAT solution. ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3622672
更新日期：2011-09-01 00:00:00
abstract：PURPOSE:When designing a collimation system for pencil beam spot scanning proton therapy, a decision must be made whether or not to rotate, or focus, the collimator to match beamlet deflection as a function of off-axis distance. If the collimator is not focused, the beamlet shape and fluence will vary as a function of ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14139
更新日期：2020-07-01 00:00:00
abstract：PURPOSE:The purpose of this work is twofold: First, to characterize the artifacts occurring in helical 4D-CT imaging; second, to propose a method that can automatically identify the artifacts in 4D-CT images. The authors have designed a process that can automatically identify the artifacts in 4D-CT images, which may be...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3553556
更新日期：2011-04-01 00:00:00
abstract：PURPOSE:This report describes upgrades and performance characterization of an experimental benchtop cone-beam x-ray fluorescence computed tomography (XFCT) system capable of determining the spatial distribution and concentration of metal probes such as gold nanoparticles (GNPs). Specifically, a high-power (~3 kW) indus...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13138
更新日期：2018-10-01 00:00:00
abstract：:The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power sp...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3097284
更新日期：2009-04-01 00:00:00
abstract：:A computed tomography (CT) based system that compensates for patient surface contour and internal tissue inhomogeneity was implemented in our clinic. The compensators are fabricated with a mixture of tin granules and bee's wax. The tin/wax mixture was optimized for tin granule size and tin granule to wax ratio. The na...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597303
更新日期：1994-03-01 00:00:00
abstract：PURPOSE:Total and regional body composition are important indicators of health and mortality risk, but their measurement is usually restricted to controlled environments in clinical settings with expensive and specialized equipment. A method that approaches the accuracy of the current gold standard method, dual-energy ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14492
更新日期：2020-12-01 00:00:00
abstract：PURPOSE:The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4939663
更新日期：2016-02-01 00:00:00
abstract：:Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmet...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598615
更新日期：1999-07-01 00:00:00
abstract：PURPOSE:This study aims to investigate carotid plaque calcification (CPC) using two-dimensional (2D) and 3D ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequences and compare T1, T2*, water concentration, and bone mineral density (BMD) of CPC with those of cortical bone. METHODS:Twelve carotid plaque sp...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4819944
更新日期：2013-10-01 00:00:00
abstract：PURPOSE:Having been overlooked for many years, research is now starting to take into account the directional distribution of neutron workplace fields. Existing neutron dosimetry instrumentation does not account for this directional distribution, resulting in conservative estimates of dose in neutron workplace fields (b...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4964456
更新日期：2016-11-01 00:00:00
abstract：PURPOSE:To introduce a novel laser-based optical-CT scanner for the readout of three-dimensional (3D) radiation dosimeters. METHODS:The scanner employs a diode laser, a cylindrical lens, a motorized linear rail, a rotation stage, and a charge-coupled device camera. The scanner operates in a translate-rotate fashion an...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3538924
更新日期：2011-02-01 00:00:00
abstract：PURPOSE:To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). METHODS:Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4963213
更新日期：2016-10-01 00:00:00
abstract：PURPOSE:Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as inter...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4948999
更新日期：2016-06-01 00:00:00
abstract：PURPOSE:To investigate how the setting of optimization parameters, fractional dose and tuning structure in tomotherapy treatment planning affects plan dosimetric quality and treatment efficiency. METHODS:A digital phantom to simulate head and neck radiotherapy was constructed for this study. Tumor was 10cm long C-shap...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735724
更新日期：2012-06-01 00:00:00
abstract：:One limitation to the widespread implementation of Monte Carlo (MC) patient dose-calculation algorithms for radiotherapy is the lack of a general and accurate source model of the accelerator radiation source. Our aim in this work is to investigate the sensitivity of the photon-beam subsource distributions in a MC sour...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1884385
更新日期：2005-04-01 00:00:00
abstract：PURPOSE:Since the introduction of clinical x-ray phase-contrast mammography (PCM), a technique that exploits refractive-index variations to create edge enhancement at tissue boundaries, a number of optimization studies employing physical image-quality metrics have been performed. Ideally, task-based assessment of PCM w...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3676183
更新日期：2012-02-01 00:00:00
abstract：PURPOSE:To reduce image noise and radiation dose in Digital Breast Tomosynthesis (DBT) reconstructions. METHODS:A retrospective study was performed on clinical data sets acquired at a normal dose with Hologic Selenia Dimensions DBT systems. The Prior Image Constrained Compressed Sensing (PICCS) algorithm was used to r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735982
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4894728
更新日期：2014-10-01 00:00:00
abstract：:Effectiveness of an oral presentation depends on the ability of the speaker to communicate with the audience. An important part of this communication is focusing on two to five key points and emphasizing those points during the presentation. Every aspect of the presentation should be purposeful and directed at facilit...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735944
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be fu...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4948498
更新日期：2016-06-01 00:00:00
