Abstract：
:The attenuating properties of several types of lead (Pb)-based and non-Pb radiation shielding materials were studied and a correlation was made of radiation attenuation, materials properties, calculated spectra and ambient dose equivalent. Utilizing the well-characterized x-ray and gamma ray beams at the National Research Council of Canada, air kerma measurements were used to compare a variety of commercial and pre-commercial radiation shielding materials over mean energy ranges from 39 to 205 keV. The EGSnrc Monte Carlo user code cavity. cpp was extended to provide computed spectra for a variety of elements that have been used as a replacement for Pb in radiation shielding garments. Computed air kerma values were compared with experimental values and with the SRS-30 catalogue of diagnostic spectra available through the Institute of Physics and Engineering in Medicine Report 78. In addition to garment materials, measurements also included pure Pb sheets, allowing direct comparisons to the common industry standards of 0.25 and 0.5 mm "lead equivalent." The parameter "lead equivalent" is misleading, since photon attenuation properties for all materials (including Pb) vary significantly over the energy spectrum, with the largest variations occurring in the diagnostic imaging range. Furthermore, air kerma measurements are typically made to determine attenuation properties without reference to the measures of biological damage such as ambient dose equivalent, which also vary significantly with air kerma over the diagnostic imaging energy range. A single material or combination cannot provide optimum shielding for all energy ranges. However, appropriate choice of materials for a particular energy range can offer significantly improved shielding per unit mass over traditional Pb-based materials.
journal_name
Med Physjournal_title
Medical physicsauthors
McCaffrey JP,Shen H,Downton B,Mainegra-Hing Edoi
10.1118/1.2426404subject
Has Abstractpub_date
2007-02-01 00:00:00pages
530-7issue
2eissn
0094-2405issn
2473-4209journal_volume
34pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS:The phantom presents a set of m...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13952
更新日期：2020-02-01 00:00:00
abstract：:The computational aspects of the design of an optical distance indicator (ODI) for use with a radiation therapy accelerator are discussed. The specifics of the optical and mechanical design of an ODI for use with a superconducting cyclotron used for fast neutron therapy are presented. ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598510
更新日期：1999-02-01 00:00:00
abstract：PURPOSE:We propose a new metric called Distance Discordance (DD), which is defined as the distance between two anatomic points from two moving images, which are co-located on some reference image, when deformed onto another reference image. METHODS:To demonstrate the concept of DD, we created a reference software phan...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736139
更新日期：2012-06-01 00:00:00
abstract：OBJECTIVE:To develop an anthropomorphic, deformable and multimodal pelvis phantom with positron emission tomography extension for radiotherapy (ADAM PETer). METHODS:The design of ADAM PETer was based on our previous pelvis phantom (ADAM) and extended for compatibility with PET and use in 3T magnetic resonance imaging ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14597
更新日期：2020-11-18 00:00:00
abstract：:Part III (oral exam) is the final part of ABR board exam for Diagnostic Medical Physics. In this exam, each of five oral examiners questions the candidate in each of five question categories. Oral exam has unique challenges to the candidate compared with the written exams. The candidate is expected to have not only ad...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736136
更新日期：2012-06-01 00:00:00
abstract：:When a catheter is inserted through an artery, the wall shear stress increases and the secondary flow exhibits an increased number of instantaneous vortices. These effects become more evident when the annular gap between the catheter and the artery becomes more narrow. Accordingly it is suggested that these factors ma...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596448
更新日期：1990-09-01 00:00:00
abstract：:A four-parameter Laplace transform pair model, which accurately reconstructs an experimental bremsstrahlung spectrum from attenuation data, is presented. Computed spectral values with both aluminum and copper attenuators generally agree with experimental 70-kVp data to better than 2%. Reconstructed spectra at other kV...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595193
更新日期：1982-11-01 00:00:00
abstract：PURPOSE:There is evidence that computed tomography (CT) and positron emission tomography (PET) imaging metrics are prognostic and predictive in nonsmall cell lung cancer (NSCLC) treatment outcomes. However, few studies have explored the use of standardized uptake value (SUV)-based image features of nodal regions as pre...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4926755
更新日期：2015-08-01 00:00:00
abstract：:An artificial neural network using input data derived from attenuation measurements was trained to generate spectral profiles (relative number of photons versus energy). Once the relative spectral distribution is reconstructed, absolute spectra (number of photons per unit exposure spectral distribution is reconstructe...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596495
更新日期：1990-07-01 00:00:00
abstract：:The physical characteristics of a clinical charge coupled device (CCD)-based imager (Senovision, GE Medical Systems, Milwaukee, WI) for small-field digital mammography have been investigated. The imager employs a MinR 2000 (Eastman Kodak Company, Rochester, NY) scintillator coupled by a 1:1 optical fiber to a front-il...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1286720
更新日期：2000-08-01 00:00:00
abstract：PURPOSE:To evaluate the availability and performance of pencil beam algorithm for fast neutrons radiotherapy dose calculations and to achieve improvements in universality, speed and inhomogeneities corrections. METHODS:Pencil beam (PB) method uses integration of dose kernel cross field size to estimate dose distributi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735630
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Tumor grading is an important part of breast cancer diagnosis and currently requires biopsy as its standard. Here, the authors investigate quantitative ultrasound parameters in locally advanced breast cancers that can potentially separate tumors from normal breast tissue and differentiate tumor grades. METHODS...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4852875
更新日期：2014-01-01 00:00:00
abstract：PURPOSE/OBJECTIVE:Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12104
更新日期：2017-03-01 00:00:00
abstract：:The objective of this study was to compare the contrast-detail performance of five different commercial liquid crystal displays (LCDs) to other LCD and cathode-ray tube (CRT) displays for medical applications. A contrast-detail phantom, supplemented with 5 in. of acrylic, was imaged on a commercial digital radiographi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2868780
更新日期：2008-04-01 00:00:00
abstract：:A nondestructive and noninvasive method for numeric characterization (quantification) of the structural composition of human bone tissue has been developed and tested. In order to quantify and to compare the structural composition of bones from 2D computed tomography (CT) images acquired at different skeletal location...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2336501
更新日期：2006-10-01 00:00:00
abstract：PURPOSE:Treatments like radiotherapy and focused ultrasound in the abdomen require accurate motion tracking, in order to optimize dosage delivery to the target and minimize damage to critical structures and healthy tissues around the target. 4D ultrasound is a promising modality for motion tracking during such treatmen...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4890091
更新日期：2014-08-01 00:00:00
abstract：PURPOSE:The management of thoracic malignancies with radiation therapy is complicated by continuous target motion. In this study, a real time motion analysis approach is proposed to improve the accuracy of patient setup. METHODS:For 11 lung cancer patients a long training fluoroscopy was acquired before the first trea...
journal_title：Medical physics
pub_type： 临床试验,杂志文章
doi：10.1118/1.4794489
更新日期：2013-04-01 00:00:00
abstract：PURPOSE:To characterize a new air vented ionization chamber technology, suitable to build detector arrays with small pixel pitch and independence of sensitivity on dose per pulse. METHODS:The prototype under test is a linear array of air vented ionization chambers, consisting of 80 pixels with 3.5 mm pixel pitch dista...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4945414
更新日期：2016-05-01 00:00:00
abstract：:A proton dose computational algorithm, performing an analytical superposition of infinitely narrow proton beamlets (ASPB) is introduced. The algorithm uses the standard pencil beam technique of laterally distributing the central axis broad beam doses according to the Moliere scattering theory extended to slablike vary...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2064887
更新日期：2005-12-01 00:00:00
abstract：:Up to the present, the majority of low contrast object evaluations performed on phantom images have been accomplished in a subjective fashion. This is mainly due to the time and effort required to manually measure each radiograph with a densitometer to obtain quantitative results. However, with the development of digi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1543153
更新日期：2003-03-01 00:00:00
abstract：PURPOSE:The segmentation accuracy of medical images was improved by increasing the number of training samples using a local image warping technique. The performance of the proposed method was evaluated in the segmentation of breast masses, prostate and brain tumors, and lung nodules. METHODS:We propose a simple data a...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14651
更新日期：2020-12-10 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:To demonstrate the feasibility of compressed sensing (CS) to accelerate the acquisition of hyperpolarized (HP) 129 Xe multi-b diffusion MRI for quantitative assessments of lung microstructural morphometry. METHODS:Six healthy subjects and six chronic obstructive pulmonary disease (COPD) subjects underwent HP 1...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12944
更新日期：2018-07-01 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：:The modulation transfer function (MTF) of a screen-film system can be measured by two methods, i.e., a slit method with Fourier transform on the line spread function and a square-wave response function (SWRF) method. However, it is still uncertain whether MTFs obtained by the two methods are identical. In this study, ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597456
更新日期：1995-02-01 00:00:00
abstract：:Calcium concentration may be a useful feature for distinguishing benign from malignant lung nodules in computer-aided diagnosis. The calcium concentration can be estimated from the measured CT number of the nodule and a CT number vs calcium concentration calibration line that is derived from CT scans of two or more ca...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3148536
更新日期：2009-07-01 00:00:00
abstract：PURPOSE:This paper describes the low-kV spectral optimization of dual-energy CT (DECT) equipped with high-kV tin filtration for the quantitative acquisition of electron density information, which is essential for treatment planning in radiotherapy. In addition, an analytical DECT image simulation was preliminarily perf...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3584200
更新日期：2011-06-01 00:00:00
abstract：:This article provides a quantitative evaluation of Varian Medical Systems' beam matching procedure. A one-dimensional y analysis is employed to investigate the level of agreement of matched beams. A customized concept of one-dimensional gamma evaluation was designed. Our algorithm first performs a "local" fit of the r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2745239
更新日期：2007-07-01 00:00:00
abstract：:DICOM format is the de facto standard for communications between therapeutic and diagnostic modalities. A plan generated by a treatment planning system (TPS) is often exported to DICOM format. BEAMnrc/DOSXYZnrc is a widely used Monte Carlo (MC) package for beam and dose simulations in radiotherapy. It has its own defi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4740186
更新日期：2012-07-01 00:00:00
abstract：PURPOSE:To develop an automated technique for evaluating lung stereotactic body radiotherapy (SBRT) plan quality and predicting achievable lung dose constraints. METHODS:We examined the workflow scripting capabilities of a radiation oncology software package (MIM Software Inc) for automatically generating mean dose gr...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735279
更新日期：2012-06-01 00:00:00
