Abstract：
PURPOSE:The goal of this work is to propose a new multichannel method correcting for systematic thickness disturbances and to evaluate its precision in relevant radiation dosimetry applications. METHODS:The eigencolor ratio technique is introduced and theoretically developed to provide a method correcting for thickness disturbances. The method is applied to EBT3 GafchromicTM film irradiated with cobalt-60 and 6 MV photon beams and digitized with an Epson 10000XL photo scanner. Dose profiles and output factors of different field sizes are measured and analyzed. Variance analysis of the previous method of Bouchard et al. ["On the characterization and uncertainty analysis of radiochromic film dosimetry" Med.Phys. 36(6), 1931-1946 (2009)] is adapted to the new approach. Uncertainties are predicted for relevant applications. RESULTS:Results show that systematic disturbances attributed to thickness variations are efficiently corrected. The method is shown efficient to identify and correct for dark spots which cause systematic errors in single-channel distributions. Applications of the method in the context of relative dosimetry yields standard uncertainties ranging between 0.8% and 1.9%, depending on the ROI size and the film irradiation. Variance analysis predicts that uncertainty levels between 0.3% and 0.6% are achievable with repeated measurements. Uncertainties are found to vary with absorbed dose and ROI size. CONCLUSIONS:The proposed multichannel method is efficient for accurate dosimetry, reaching uncertainty levels comparable to previous publications with EBT film. The method is also promising for applications beyond clinical QA, such as machine characterization and other advanced dosimetry applications.
journal_name
Med Physjournal_title
Medical physicsauthors
Bouchard H,Billas I,Subie A,Duane Sdoi
10.1002/mp.14742subject
Has Abstractpub_date
2021-02-01 00:00:00eissn
0094-2405issn
2473-4209pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595546
更新日期：1984-09-01 00:00:00
abstract：:We measured the physical imaging performance of a 41 x 41 cm2 amorphous silicon flat panel detector designed for angiographic and R&F imaging applications using methods from the emerging IEC standard for the measurement of detective quantum efficiency (DQE) in digital radiographic detectors. Measurements on 12 product...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1609151
更新日期：2003-10-01 00:00:00
abstract：:Accurate segmentation of microcalcifications in mammography is crucial for the quantification of morphologic properties by features incorporated in computer-aided diagnosis schemes. A novel segmentation method is proposed implementing active rays (polar-transformed active contours) on B-spline wavelet representation t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2991286
更新日期：2008-11-01 00:00:00
abstract：PURPOSE:A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible corre...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4964449
更新日期：2016-11-01 00:00:00
abstract：PURPOSE:The aim of this study is to investigate the performance of Sentinel(™), a patient setup verification device based on a laser/camera system, when used on rigid-body phantoms. METHODS:The Sentinel system consists of a scanner unit, containing the laser and the camera, and surface-matching registration software. ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3675973
更新日期：2012-02-01 00:00:00
abstract：PURPOSE:Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3519873
更新日期：2011-01-01 00:00:00
abstract：PURPOSE:Hybrid radiotherapy-MRI devices promise real time tracking of moving tumors to focus the radiation portals to the tumor during irradiation. This approach will benefit from the increased temporal resolution of MRI's data acquisition and reconstruction. In this work, the authors propose a novel spatial-temporal c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4885960
更新日期：2014-08-01 00:00:00
abstract：PURPOSE:To demonstrate, via Monte Carlo simulation, that an image obtained from the patient-generated scattered radiation forced to impinge on the detector from a known direction by means of parallel-focused grids, can be used to complement the information conveyed by the primary image, such that accurate stereoscopic ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12712
更新日期：2018-02-01 00:00:00
abstract：PURPOSE:Silicon photodetectors are of significant interest for use in positron emission tomography (PET) systems due to their compact size, insensitivity to magnetic fields, and high quantum efficiency. However, one of their main disadvantages is fluctuations in temperature cause strong shifts in gain of the devices. P...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4903889
更新日期：2015-01-01 00:00:00
abstract：:The NSD equation, D = 1850 x T0.11 x N0.24, is a celebrated transmogrification of Cohen's two well-known collations of data on response to clinical irradiations (3 degrees erythema and 0.90 ablation of skin cancer) in which the relation of D and T is fixed by the data selected by Cohen and the additional constraint th...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595034
更新日期：1981-11-01 00:00:00
abstract：:Contemporary reconstruction methods employed for clinical helical cone-beam computed tomography (CT) are analytical (noniterative) but mathematically nonexact, i.e., the reconstructed image contains so called cone-beam artifacts, especially for higher cone angles. Besides cone artifacts, these methods also suffer from...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2966353
更新日期：2008-09-01 00:00:00
abstract：PURPOSE:There is significant current interest in the use of biological image guidance in radiotherapy planning. In lung-cancer treatment, tumor motion due to respiration is known to be a limitation. This is particularly true in PET, where image data are collected over a number of minutes. An in-house-developed 4D PET a...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3276776
更新日期：2010-02-01 00:00:00
abstract：PURPOSE:Computed tomography (CT) is one of the most used imaging modalities for imaging both symptomatic and asymptomatic patients. However, because of the high demand for lower radiation dose during CT scans, the reconstructed image can suffer from noise and artifacts due to the trade-off between the image quality and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12523
更新日期：2017-10-01 00:00:00
abstract：PURPOSE:This article presents a new reconstruction method for 3D imaging using a multiple 360 degrees circular orbit cone beam CT system, specifically a way to combine 3D volumes reconstructed with each orbit. The main goal is to improve the noise performance in the combined image while avoiding cone beam artifacts. M...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3484058
更新日期：2010-10-01 00:00:00
abstract：:Myocardial beta adrenergic receptor (beta-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasiv...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2402585
更新日期：2007-01-01 00:00:00
abstract：:The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rush...
journal_title：Medical physics
pub_type： 杂志文章,评审
doi：10.1118/1.3002314
更新日期：2008-12-01 00:00:00
abstract：PURPOSE:The performance of a newly developed, high resolution, microangiographic fluoroscope (MAF) (35 μm pixel pitch and 300 μm thick CsI phosphor) was evaluated using a generalized linear system analysis and compared with that of a standard amorphous Si thin film transistor flat panel detector (FPD) (194 μm pixel pit...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4792460
更新日期：2013-03-01 00:00:00
abstract：PURPOSE:An improvement in tissue assignment for low-dose rate brachytherapy (LDRB) patients using more accurate Monte Carlo (MC) dose calculation was accomplished with a metallic artifact reduction (MAR) method specific to dual-energy computed tomography (DECT). METHODS:The proposed MAR algorithm followed a four-step ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4947486
更新日期：2016-05-01 00:00:00
abstract：PURPOSE:The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides exce...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4914860
更新日期：2015-04-01 00:00:00
abstract：PURPOSE:As radiation therapy evolves toward more adaptive techniques, image guidance plays an increasingly important role, not only in patient setup but also in monitoring the delivered dose and adapting the treatment to patient changes. This study aimed to validate a method for evaluation of delivered intensity modula...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4903292
更新日期：2015-01-01 00:00:00
abstract：PURPOSE:Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4962483
更新日期：2016-10-01 00:00:00
abstract：:Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1406519
更新日期：2001-10-01 00:00:00
abstract：PURPOSE:The purpose of this study is to evaluate the feasibility of kilovoltage cone-beam CT (CBCT) images that are obtained with the Varian On-Board Imager in dose calculation at each radiation therapy. METHODS:CBCT images are commonly degraded by scattered radiations originating in the patient's body, and so the CT ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734936
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Hybrid Photon Counting (HPC) detectors profoundly improved x-ray diffraction experiments at third generation synchrotron facilities. Enabling the simultaneous measurement of x-ray intensities in multiple energy bins, they also have many potential applications in the field of medical imaging. A prerequisite for ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12323
更新日期：2017-09-01 00:00:00
abstract：PURPOSE:Pulse pileup occurring at high x-ray fluxes can severely degrade the energy resolution provided by a photon counting detector, which can represent a problem in spectroscopic CT when performing quantitative material discrimination tasks. As the effects of pileup can be most easily seen as a degradation of a dete...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4820535
更新日期：2013-10-01 00:00:00
abstract：PURPOSE:Computed tomography (CT) intrascanner and interscanner variability has not been well characterized. Thus, the purpose of this study was to examine the within-run, between-run, and between-scanner precision of physical dosimetry-related measurements collected over the course of 1 yr on three different makes and ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3426000
更新日期：2010-08-01 00:00:00
abstract：PURPOSE:For the purpose of size-specific dose estimation, information regarding patient attenuation is required. The purpose of this work is to describe a method for measuring patient attenuation and expressing the results in terms of a water cylinder, with cross sectional area A(w), which would absorb the same average...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4754303
更新日期：2012-11-01 00:00:00
abstract：:The authors present an alternative approach to inverse planning optimization and apply it to volumetric modulated are therapy (VMAT) in one rotation with a prior knowledge about the type of leaf motions. The optimization is based on the projection theorem in inner product spaces. MLC motion is directly considered in t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3173815
更新日期：2009-08-01 00:00:00
abstract：PURPOSE:Identification of calcifications and hemorrhages is essential for the etiological diagnosis of cerebral lesions. The purpose of this work was to develop a robust method for characterization of para- and diamagnetic intracerebral lesions based on clinical gradient-echo magnetic resonance phase data acquired at 1...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3481505
更新日期：2010-10-01 00:00:00
abstract：PURPOSE:Respiratory gating in PET is an approach used to minimize the negative effects of respiratory motion on spatial resolution. It is based on an initial determination of a patient's respiratory movements during a scan, typically using hardware based systems. In recent years, several fully automated databased algor...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3483784
更新日期：2010-10-01 00:00:00
