Dosimetric aspects of a 3.3-MV linear accelerator.

abstract：PURPOSE:Current respiratory motion monitoring devices used for motion synchronization in medical imaging and radiotherapy provide either 1D respiratory signal over a specific region or 3D information based on few external or internal markers. On the other hand, newer technology may offer the potential to monitor the en...

journal_title：Medical physics

authors： Fayad H,Pan T,Clement JF,Visvikis D

更新日期：2011-06-01 00:00:00

abstract：PURPOSE:The authors' objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-sp...

journal_title：Medical physics

authors： Grimes J,Celler A

更新日期：2014-09-01 00:00:00

abstract：:Errors in the determination of xenon concentrations in arterial blood during inhalation of xenon-oxygen mixtures are used to assess errors in the derivation of regional cerebral blood flow by the xenon-enhanced computed tomography (CT) method. The results of this study indicate that approximating the arterial buildup ...

journal_title：Medical physics

authors： Good WF,Gur D,Yonas H,Herron JM

更新日期：1987-05-01 00:00:00

abstract：:Lag in fluoroscopic systems introduces a frame-averaging effect that reduces measurements of image noise and incorrectly inflates measurements of the detective quantum efficiency (DQE). A correction can be implemented based on measurements of the temporal modulation transfer function (MTF). We introduce a method of me...

journal_title：Medical physics

authors： Friedman SN,Cunningham IA

更新日期：2008-06-01 00:00:00

abstract：PURPOSE:Design and optimization of medical imaging systems benefit from accurate theoretical modeling that identifies the physical factors governing image quality, particularly in the early stages of system development. This work extends Fourier metrics of imaging performance and detectability index (d') to tomosynthes...

journal_title：Medical physics

authors： Gang GJ,Lee J,Stayman JW,Tward DJ,Zbijewski W,Prince JL,Siewerdsen JH

更新日期：2011-04-01 00:00:00

abstract：:This paper examines the distributions of the SAR (specific absorption rate) ratio and temperature elevation when an ultrasound beam propagates through the interface of muscle and bone. This interface is regarded as a flat boundary to partition the energy of the ultrasound beam, and the analytical solution of temperatu...

journal_title：Medical physics

authors： Lin WL,Liauh CT,Chen YY,Liu HC,Shieh MJ

更新日期：2000-05-01 00:00:00

abstract：:This paper compares the characteristics of three types of commercial p-type electron diodes specially designed for in vivo dosimetry (Scanditronix EDD2, Sun Nuclear QED 111200-0 and PTW T60010E diodes coupled with a Therados DPD510 dosimeter) in electron fields with energies from 4.5 to 21 MeV, and in conditions simil...

journal_title：Medical physics

authors： Marre D,Marinello G

更新日期：2004-01-01 00:00:00

abstract：:In prostate seed implants, radioactive seeds are implanted into the prostate through a guiding needle with the help of a template and real-time imaging. The ideal locations of the guiding needles and the relative positions of the seeds in each needle are determined before the implantation under the assumption that the...

journal_title：Medical physics

authors： Nath S,Chen Z,Yue N,Trumpore S,Peschel R

更新日期：2000-05-01 00:00:00

abstract：:Subsecond single-slice, multi-slice or cone-beam spiral computed tomography (SSCT, MSCT, CBCT) offer great potential for improving heart imaging. Together with the newly developed phase-correlated cardiac reconstruction algorithms 180 degrees MCD and 180 degrees MCI [Med. Phys. 27, 1881-1902 (2000)] or related algorit...

journal_title：Medical physics

authors： Kachelriess M,Sennst DA,Maxlmoser W,Kalender WA

更新日期：2002-07-01 00:00:00

abstract：:We compare the results of absorbed dose determined at reference conditions according to the AAPM TG-21 dose calibration protocol and the new AAPM TG-51 protocol. The AAPM TG-21 protocol for absorbed dose calibration is based on ionization chambers having exposure calibration factors for 60Co gamma rays, N(x). The new ...

journal_title：Medical physics

authors： Ding GX,Cygler JE,Kwok CB

更新日期：2000-06-01 00:00:00

abstract：:Gafchromic XRCT, radiochromic film is assessed over a broad energy range, from kilovoltage to megavoltage x rays for variations in reflected optical density to dose response. A large energy dependence was found with reflected optical density output for the same delivered dose varying from 7.8 +/- 0.35 at 25.5 keV (50 ...

journal_title：Medical physics

authors： Butson MJ,Cheung T,Yu PK

更新日期：2006-08-01 00:00:00

abstract：PURPOSE:Experimental dosimetry of high-dose-rate (HDR) 192 Ir brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high se...

journal_title：Medical physics

authors： Kaveckyte V,Malusek A,Benmakhlouf H,Alm Carlsson G,Carlsson Tedgren Å

更新日期：2018-01-01 00:00:00

abstract：:A method is proposed for realistic simulation of the breast ductal network as part of a computer three-dimensional (3-D) breast phantom. The ductal network is simulated using tree models. Synthetic trees are generated based upon a description of ductal branching by ramification matrices (R matrices), whose elements re...

journal_title：Medical physics

authors： Bakic PR,Albert M,Brzakovic D,Maidment AD

更新日期：2003-07-01 00:00:00

abstract：PURPOSE:To evaluate if the recently described problems with the calibration of jaws at Varian linear accelerators can be detected with the DAVID system. METHODS:Recently Varian Clinac field size issues resulted in a widespread medical device correction notice, stating that incorrect jaw positioning due to excessive co...

journal_title：Medical physics

authors： Poppe B,Looe H,Harder D

更新日期：2012-06-01 00:00:00

abstract：:We are evaluating the usefulness of stereomammography in improving breast cancer diagnosis. One area that we are investigating is whether the improved depth perception associated with stereomammography might be significantly enhanced with the use of a virtual 3D cursor. A study was performed to evaluate the accuracy o...

journal_title：Medical physics

authors： Goodsitt MM,Chan HP,Hadjiiski L

更新日期：2000-06-01 00:00:00

abstract：PURPOSE:Recently, brain tumor segmentation has made important progress. However, the quality of manual labels plays an important role in the performance, while in practice, it could vary greatly and in turn could substantially mislead the learning process and decrease the accuracy. We need to design a mechanism to comb...

journal_title：Medical physics

authors： Cheng G,Ji H,He L

更新日期：2020-09-24 00:00:00

abstract：PURPOSE:Metastatic melanoma lesions experienced marked regression after systemic targeted alpha therapy in a phase 1 clinical trial. This unexpected response was ascribed to tumor antivascular alpha therapy (TAVAT), in which effective tumor regression is achieved by killing endothelial cells (ECs) in tumor capillaries ...

journal_title：Medical physics

authors： Huang CY,Oborn BM,Guatelli S,Allen BJ

更新日期：2012-03-01 00:00:00

abstract：PURPOSE:Fluence field modulated computed tomography (FFMCT) presents a novel approach for acquiring CT images, whereby a patient model guides dynamically changing fluence patterns in an attempt to achieve task-based, user-prescribed, regional variations in image quality, while also controlling dose to the patient. This...

journal_title：Medical physics

authors： Bartolac S,Jaffray D

更新日期：2013-12-01 00:00:00

abstract：PURPOSE:The aim of the study was to evaluate the impact of multileaf collimator (MLC) leaf width on treatment adaptation and delivery accuracy for concurrent treatment of the prostate and pelvic lymph nodes with intensity modulated radiation therapy (IMRT). METHODS:Seventy-five kilovoltage cone beam CTs (KV-CBCT) from...

journal_title：Medical physics

authors： Shang Q,Qi P,Ferjani S,Xia P

更新日期：2013-06-01 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：:We have reexamined the problem of estimating the luminal area of an elliptically shaped coronary artery cross section from two or more radiographic diameter measurements. The expected error is found to be much smaller than the maximum potential error. In the cases of two orthogonal views, closed form expressions have ...

journal_title：Medical physics

authors： Lee PL,Selzer RH

更新日期：1988-07-01 00:00:00

abstract：PURPOSE:To develop and evaluate a tool for accurate, reproducible, and programmable motion control of imaging phantoms for use in motion sensitive magnetic resonance imaging (MRI) appli cations. METHODS:In this paper, the authors introduce a compact linear motion stage that is made of nonmagnetic material and is actua...

journal_title：Medical physics

authors： Tavallaei MA,Johnson PM,Liu J,Drangova M

更新日期：2016-01-01 00:00:00

abstract：:The trend toward conformal techniques in stereotactic radiosurgery necessitates an accurate and practical method for verification of irregular three-dimensional dose distributions. This work presents the design and evaluation of a phantom system facilitating the measurement of conformal dose distributions using one or...

journal_title：Medical physics

authors： Robar JL,Clark BG

更新日期：2000-05-01 00:00:00

abstract：PURPOSE:Onboard imaging-currently performed primarily by x-ray transmission modalities-is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single pho...

journal_title：Medical physics

authors： Bowsher J,Yan S,Roper J,Giles W,Yin FF

更新日期：2014-01-01 00:00:00

abstract：:A suitable was phantom was designed for evaluating various film techniques used in subtraction radiography. Holes are drilled in a slab of wax and filled with various concentrations of iodinated wax, producing disk-shaped regions with diffuse borders. The technical details of construction and a representative applicat...

journal_title：Medical physics

authors： Ort MG,Gregg EC

更新日期：1977-05-01 00:00:00

abstract：PURPOSE:To investigate the inconsistency of recent literature on the effect of magnetic field on the response of radiochromic films, we studied the influence of 0.35 T magnetic field on dosimetric response of EBT3 and EBT-XD GafchromicTM films. METHODS:Two different models of radiochromic films, EBT3 and EBT-XD, were ...

journal_title：Medical physics

authors： Darafsheh A,Hao Y,Maraghechi B,Cammin J,Reynoso FJ,Khan R

更新日期：2020-09-01 00:00:00

abstract：:Computed tomography dose index (CTDI) is a conventional indicator of the patient dose in CT studies. It is measured as the integration of the longitudinal single scan dose profile (SSDP) by using a 100-mm-long pencil ionization chamber and a single axial scan. However, the assumption that most of the SSDP is contained...

journal_title：Medical physics

authors： Nakonechny KD,Fallone BG,Rathee S

更新日期：2005-01-01 00:00:00

abstract：PURPOSE:Two-dimensional antiscatter grids (2DASG) for cone beam computed tomography (CBCT) is a new area of research to reduce scatter intensity, and consequently improve CBCT image quality. One of the challenges in implementation of 2DASGs is their septa shadows that are impinged on the projections. If these artifacts...

journal_title：Medical physics

authors： Alexeev T,Kavanagh B,Miften M,Altunbas C

更新日期：2019-05-01 00:00:00

abstract：PURPOSE:Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the ...

journal_title：Medical physics

authors： Xia W,Piras D,van Hespen JC,van Veldhoven S,Prins C,van Leeuwen TG,Steenbergen W,Manohar S

更新日期：2013-03-01 00:00:00

abstract：PURPOSE:The accuracy of a six degree of freedom (6DoF) couch was evaluated using a novel method. METHODS:Cone beam CT (CBCT) images of a 3D phantom (IsoCal) were acquired with different, known combinations of couch pitch and roll angles. Pitch and roll angles between the maximum allowable values of 357 and 3 degrees w...

journal_title：Medical physics

authors： Zhang Q,Driewer J,Wang S,Li S,Zhu X,Zheng D,Cao Y,Zhang J,Jamshidi A,Cox BW,Knisely JPS,Potters L,Klein EE

更新日期：2017-08-01 00:00:00