Reconstruction of 4-MV bremsstrahlung spectra from measured transmission data.

abstract：PURPOSE:The most common metric for comparing measured to calculated dose planes is a pass rate generated using percent difference, distance-to-agreement (DTA), or some combination of the two (e.g. gamma evaluation). The grid of analyzed points often corresponds to a dosimeter array with low areal-density of point detec...

journal_title：Medical physics

authors： Bailey D,Nelms B,Kumaraswamy L,Attwood K,Podgorsak M

更新日期：2012-06-01 00:00:00

abstract：:The purpose of this work is to compare the efficacy of mathematical models in predicting the occurrence of radiotherapy-induced left ventricular perfusion defects assessed using single-photon emission computed tomography (SPECT). The basis of this study is data from 73 left-sided breast/ chestwall patients treated wit...

journal_title：Medical physics

authors： Das SK,Baydush AH,Zhou S,Miften M,Yu X,Craciunescu O,Oldham M,Light K,Wong T,Blazing M,Borges-Neto S,Dewhirst MW,Marks LB

更新日期：2005-01-01 00:00:00

abstract：PURPOSE:Dual source CT (DSCT) systems utilize two measurement systems (A) and (B) offset by about 90 degrees. A special challenge in DSCT is cross-scattered radiation, i.e., scattered radiation from x-ray tube (B) detected in detector (A) and vice versa. Cross-scattered radiation can produce artifacts and degrade the c...

journal_title：Medical physics

authors： Petersilka M,Stierstorfer K,Bruder H,Flohr T

更新日期：2010-11-01 00:00:00

abstract：:The performance of a diode array (Profiler) was evaluated by comparing its enhanced dynamic wedge (EDW) profiles measured at various depths with point measurements using a 0.03 cm3 ionization chamber on a commercial linear accelerator. The Profiler, which covers a 22.5 cm width, was used to measure larger field widths...

journal_title：Medical physics

authors： Zhu TC,Ding L,Liu CR,Palta JR,Simon WE,Shi J

更新日期：1997-07-01 00:00:00

abstract：:The aim of this work was to test the suitability of a PTW diamond detector for nonreference condition dosimetry in photon beams of different energy (6 and 25 MV) and field size (from 2.6 cm x 2.6 cm to 10 cm x 10 cm). Diamond behavior was compared to that of a Scanditronix p-type silicon diode and a Scanditronix RK io...

journal_title：Medical physics

authors： Bucciolini M,Buonamici FB,Mazzocchi S,De Angelis C,Onori S,Cirrone GA

更新日期：2003-08-01 00:00:00

abstract：:In previous work it has been shown that a standard backpropagation neural network can be trained to reconstruct sections of single photon emission computed tomography (SPECT) images based on the planar image projections as inputs. In this study, it is demonstrated that an artificial neural network (ANN) trained on a s...

journal_title：Medical physics

authors： Kerr JP,Bartlett EB

更新日期：1995-05-01 00:00:00

abstract：PURPOSE:X-ray phase-contrast tomography (PCT) is a rapidly emerging imaging modality for reconstructing estimates of an object's three-dimensional x-ray refractive index distribution. Unlike conventional x-ray computed tomography methods, the statistical properties of the reconstructed images in PCT remain unexplored. ...

journal_title：Medical physics

authors： Chou CY,Anastasio MA

更新日期：2010-01-01 00:00:00

abstract：PURPOSE:Accurate calculation of proton stopping power ratio (SPR) relative to water is crucial to proton therapy treatment planning, since SPR affects prediction of beam range. Current standard practice derives SPR using a single CT scan. Recent studies showed that dual-energy CT (DECT) offers advantages to accurately ...

journal_title：Medical physics

authors： Shen C,Li B,Chen L,Yang M,Lou Y,Jia X

更新日期：2018-04-01 00:00:00

abstract：PURPOSE:Our aim was to compare different magnet arrangements for magnetic cell delivery to human lower leg arteries and investigate the theoretical targeting efficiency under realistic flow conditions as a possible treatment after angioplasty. Additionally the potential of scaling down or translating the magnetic actua...

journal_title：Medical physics

authors： Riegler J,Lau KD,Garcia-Prieto A,Price AN,Richards T,Pankhurst QA,Lythgoe MF

更新日期：2011-07-01 00:00:00

abstract：:The relative sensitivity of the half-value layer (HVL) method as a quality index for megavoltage x-ray beams is examined by theoretical calculation and experimental measurements for 4-, 6-, 10-, and 25-MV x-ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher...

journal_title：Medical physics

authors： Meli JA,Nath R

更新日期：1985-01-01 00:00:00

abstract：:One of the methods currently being used to treat choroidal melanoma employs an episcleral plaque containing I-125 radioactive seeds. However, comprehensive dosimetry studies on the plaque are scarce and controversial. For this work, we use film to study the dosimetry outside the lip of the gold shield of the eye plaqu...

journal_title：Medical physics

authors： Wu A,Krasin F

更新日期：1990-09-01 00:00:00

abstract：PURPOSE:In the practice code of dosimetry, humidity effect is assumed to be constant as far as the measurements are performed in the relative humidity (RH) range of (20-80)%; thus, the humidity effect can be ignored with a dose uncertainty of 0.15%. This assumption is based on the previous experimental results by Niate...

journal_title：Medical physics

authors： Sato Y,Shimizu M,Morishita Y,Sato M,Hoshina M

更新日期：2019-09-01 00:00:00

abstract：:Accelerator-based neutron source have been considered to be practical for boron neutron capture therapy (BNCT). Based on experience with a parameters of the Brookhaven National Laboratory BMRR reactor neutron source, which has been used in treatment experiments, the future accelerator-based neutron source for BNCT sho...

journal_title：Medical physics

authors： Yu W,Yue G,Han X,Chen J,Tian B

更新日期：1998-07-01 00:00:00

abstract：PURPOSE:To investigate the effect of the number of projection views on image noise in cone-beam CT (CBCT) with a flat-panel detector. METHODS:This fairly fundamental consideration in CBCT system design and operation was addressed experimentally (using a phantom presenting a uniform medium as well as statistically moti...

journal_title：Medical physics

authors： Zhao Z,Gang GJ,Siewerdsen JH

更新日期：2014-06-01 00:00:00

abstract：PURPOSE:In radiotherapy, it is important to predict the response of tumors to irradiation prior to the treatment. This is especially important for hypoxic tumors, which are known to be highly radioresistant. Mathematical modeling based on the dose distribution, biological parameters, and medical images may help to impr...

journal_title：Medical physics

authors： Espinoza I,Peschke P,Karger CP

更新日期：2015-01-01 00:00:00

abstract：PURPOSE:Temporal subtraction is used to detect the interval change in chest radiographs and aid radiologists in patient diagnosis. This method registers two temporally different images by geometrically warping the lung region, or "lung mask," of a previous radiographic image to align with the current image. The gray le...

journal_title：Medical physics

authors： Armato SG 3rd,Sensakovic WF,Passen SJ,Engelmann R,MacMahon H

更新日期：2009-12-01 00:00:00

abstract：:The dose received in the buildup region outside the primary beam has been measured for 60Co gamma rays and 6- and 18-MV X rays. The variation of this dose with field size and depth was evaluated. The effect of blocking trays and the importance of their design was determined. ...

journal_title：Medical physics

authors： Horton JL

更新日期：1984-05-01 00:00:00

abstract：PURPOSE:Recent recommendations of the International Commission on Radiological Protection state that the use of effective dose (E) for assessing patient exposure has severe limitations, though it can be kept for dose comparisons. In cardiology procedures, the equivalent dose (H(T)) is one of the most appropriate dose q...

journal_title：Medical physics

authors： Compagnone G,Ortolani P,Domenichelli S,Ovi V,Califano G,Dall'Ara G,Marzocchi A

更新日期：2011-04-01 00:00:00

abstract：:A clamp-on current probe utilizing the Hall effect was used to determine x-ray tube current. This noninvasive technique was compared to two other methods of mA measurement: the Machlett Dynalyzer and the mR/mAs linearity method. Three diagnostic x-ray units were used in the comparison; two modern three-phase rooms and...

journal_title：Medical physics

authors： Atherton JV,Nickoloff EL

更新日期：1987-03-01 00:00:00

abstract：:The data from Meisberger et al. [Radiology 90, 953-957 (1968)] are often used as a basis for dose calculations in brachytherapy. In order to describe the absorbed dose in water around a brachytherapy point source, Meisberger provided a polynomial fit for different isotopes taking into account the effect of attenuation...

journal_title：Medical physics

authors： Tiourina TB,Dries WJ,van der Linden PM

更新日期：1995-05-01 00:00:00

abstract：PURPOSE:The purpose of this study was to describe and evaluate methods for calculating a megavoltage computed tomography (MVCT)-derived MR hardware attenuation map (μ-map) and dual-energy CT (DECT) for 511 keV photons. METHODS:Phantom measurements were acquired on a whole-body hybrid PET/MRI system, using a four-chann...

journal_title：Medical physics

authors： Patrick JC,Terry Thompson R,So A,Butler J,Faul D,Stodilka RZ,Yartsev S,Prato FS,Gaede S

更新日期：2017-09-01 00:00:00

abstract：:Ultrasound contrast agents consist of microscopically small encapsulated bubbles that oscillate upon insonification. To enhance diagnostic ultrasound imaging techniques and to explore therapeutic applications, these medical microbubbles have been studied with the aid of high-speed photography. We filmed medical microb...

journal_title：Medical physics

authors： Postema M,van Wamel A,ten Cate FJ,de Jong N

更新日期：2005-12-01 00:00:00

abstract：PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...

journal_title：Medical physics

authors： Fast MF,Wisotzky E,Oelfke U,Nill S

更新日期：2013-09-01 00:00:00

abstract：:The analysis and understanding of results of computed tomography (CT) require an understanding of photon attenuation in matter. The high sensitivity and resolution of these devices coupled with the use of a polychromatic photon source require a level and breadth of understanding about photon attenuation not usually re...

journal_title：Medical physics

authors： McCullough EC

更新日期：1975-11-01 00:00:00

abstract：PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined th...

journal_title：Medical physics

authors： Hsieh SS,Chesler DA,Fleischmann D,Pelc NJ

更新日期：2016-03-01 00:00:00

abstract：:A method is described for calibration of 192Ir high-dose-rate (HDR) brachytherapy afterloading systems. Since NIST does not offer calibration of ionization chambers with the gamma-ray spectrum of iridium-192, an interpolation procedure is employed, using calibrations above (137Cs, 662 keV) and below (250 kVcp, 146-keV...

journal_title：Medical physics

authors： Goetsch SJ,Attix FH,Pearson DW,Thomadsen BR

更新日期：1991-05-01 00:00:00

abstract：PURPOSE:Body composition is known to be associated with many diseases including diabetes, cancers, and cardiovascular diseases. In this paper, we developed a fully automatic body tissue decomposition procedure to segment three major compartments that are related to body composition analysis - subcutaneous adipose tissu...

journal_title：Medical physics

authors： Fu Y,Ippolito JE,Ludwig DR,Nizamuddin R,Li HH,Yang D

更新日期：2020-11-01 00:00:00

abstract：PURPOSE:Tissue textures have been recognized as biomarkers for various clinical tasks. In computed tomography (CT) image reconstruction, it is important but challenging to preserve the texture when lowering x-ray exposure from full- toward low-/ultra-low dose level. Therefore, this paper aims to explore the texture-dos...

journal_title：Medical physics

authors： Gao Y,Liang Z,Xing Y,Zhang H,Pomeroy M,Lu S,Ma J,Lu H,Moore W

更新日期：2020-10-01 00:00:00

abstract：:Computer-aided diagnosis (CAD) has been a major field of research for the past few decades. CAD uses machine learning methods to analyze imaging and/or nonimaging patient data and makes assessment of the patient's condition, which can then be used to assist clinicians in their decision-making process. The recent succe...

journal_title：Medical physics

authors： Chan HP,Hadjiiski LM,Samala RK

更新日期：2020-06-01 00:00:00

abstract：PURPOSE:To compare optimization characteristics, plan quality, and treatment delivery efficiency between total marrow irradiation (TMI) plans using the new TomoTherapy graphic processing unit (GPU) based dose engine and CPU/cluster based dose engine. METHODS:Five TMI plans created on an anthropomorphic phantom were op...

journal_title：Medical physics

authors： Nalichowski A,Burmeister J

更新日期：2013-07-01 00:00:00