A new pulse sequence for determining T1 and T2 simultaneously.

abstract：PURPOSE:The pulse line ion accelerator (PLIA) is a low-cost accelerator concept originally designed to accelerate heavy ions. Our group has been investigating the use of PLIA to accelerate light ions and believe a multi-stage PLIA could be useful for short half-life PET isotope production. The goal of this work was to ...

journal_title：Medical physics

authors： Behbahani RA,Diot Q,Kavanagh B,Serkova NJ,Miften M,Westerly DC

更新日期：2019-12-01 00:00:00

abstract：PURPOSE:A dynamic bowtie filter can modulate flux along both fan and view angles for reduced patient dose, scatter, and required photon flux, which is especially important for photon counting detectors (PCDs). Among the proposed dynamic bowtie designs, the piecewise-linear attenuator (Hsieh and Pelc, Med Phys. 2013;40:...

journal_title：Medical physics

authors： Shunhavanich P,Hsieh SS,Pelc NJ

更新日期：2019-01-01 00:00:00

abstract：:Monte Carlo dose calculations will potentially reduce systematic errors that may be present in currently used dose calculation algorithms. However, Monte Carlo calculations inherently contain random errors, or statistical uncertainty, the level of which decreases inversely with the square root of computation time. Our...

journal_title：Medical physics

authors： Keall PJ,Siebers JV,Jeraj R,Mohan R

更新日期：2000-03-01 00:00:00

abstract：PURPOSE:Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. METHODS:In the variational image segmen...

journal_title：Medical physics

authors： Zhao T,Ruan D

更新日期：2016-05-01 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：:Fluoroscopy is a low dose imaging technique. As such, a very sensitive detector is required to create images of good quality. Present day flat panel active matrix read out systems introduce an amount of noise that inhibits present direct and indirect methods from producing optimal quality images at fluoroscopic exposu...

journal_title：Medical physics

authors： Hunt DC,Kirby SS,Rowlands JA

更新日期：2002-11-01 00:00:00

abstract：PURPOSE:Avoiding measurement variability from 18 F phantom preparation by using 68 Ge/68 Ga phantoms for the determination of 18 F recovery curves (RC) in clinical quality assurance measurements and for PET/CT site qualification in multicentre clinical trials. METHODS:RCs were obtained from PET/CT measurements of seve...

journal_title：Medical physics

authors： Prenosil GA,Hentschel M,Fürstner M,Krause T,Weitzel T,Klaeser B

更新日期：2017-07-01 00:00:00

abstract：:MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...

journal_title：Medical physics

authors： Huang Y,Curiel L,Kukic A,Plewes DB,Chopra R,Hynynen K

更新日期：2009-06-01 00:00:00

abstract：:During our routine calibration of a Varian Clinac-20 linear accelerator, the absorbed dose for a fixed monitor unit (mu) was found to decrease with increasing dose rate. Between dose rates of 100 and 500 mu/min, there was up to 20% difference in absorbed dose for a 20-MeV electron beam. The cause of this problem was a...

journal_title：Medical physics

authors： Cheng PC,Kubo H

更新日期：1988-09-01 00:00:00

abstract：PURPOSE:Motion compensated positron emission tomography (PET) imaging requires detecting and monitoring of patient body motion. We developed a semiautomatic list-mode method to track the three-dimensional (3D) motion of fiducial positron-emitting markers during PET imaging. METHODS:A previously developed motion tracki...

journal_title：Medical physics

authors： Chamberland MJP,deKemp RA,Xu T

更新日期：2020-08-01 00:00:00

abstract：:Cardiac arrhythmias are a major health burden, associated with reduced quality of life and substantial morbidity and mortality. Current therapy includes moderately effective medication and catheter-based ablation of arrhythmogenic substrates in the heart. Catheter interventions frequently have to be repeated due to re...

journal_title：Medical physics

authors： Graeff C,Bert C

更新日期：2018-11-01 00:00:00

abstract：:The line spread function (LSF) of an imaging system incorporating a pinhole of 0.275 cm radius and a scintillation camera has been measured and its full width at half maximum (FWHM) compared to the values predicted by an expression based on the resolution index of Anger. In most cases, the actual resolution of the sys...

journal_title：Medical physics

authors： Goulet P,Joy ML

更新日期：1980-09-01 00:00:00

abstract：:High false-positive (FP) rate remains to be one of the major problems to be solved in CAD study because too many false-positively cued signals will potentially degrade the performance of detecting true-positive regions and increase the call-back rate in CAD environment. In this paper, we proposed a novel classificatio...

journal_title：Medical physics

authors： Li L,Zheng Y,Zhang L,Clark RA

更新日期：2001-02-01 00:00:00

abstract：:Optimal visualization of moving structures such as the heart and coronary arteries using digital radiographic imaging systems is a difficult problem that can involve tradeoffs between temporal, spatial, and density resolution. The motion dependence of four angiographic measures of vessel dimensions is given and demons...

journal_title：Medical physics

authors： Parker DL,Clayton PD,Gustafson DE

更新日期：1985-11-01 00:00:00

abstract：PURPOSE:The treatment of moving targets with scanned proton beams is challenging. For motion mitigation, an Active Breathing Coordinator (ABC) can be used to assist breath-holding. The delivery of pencil beam scanning fields often exceeds feasible breath-hold durations, requiring high breath-hold reproducibility. We ev...

journal_title：Medical physics

authors： den Otter LA,Kaza E,Kierkels RGJ,Meijers A,Ubbels FJF,Leach MO,Collins DJ,Langendijk JA,Knopf AC

更新日期：2018-12-01 00:00:00

abstract：PURPOSE:to use complementary cine EPID and gimbals log file analysis for in-vivo tracking accuracy monitoring. METHODS:A clinical prototype of dynamic tracking (DT) was installed on the Vero SBRT system. This prototype version allowed tumor tracking by gimballed linac rotations using an internal-external correspondenc...

journal_title：Medical physics

authors： Poels K,Depuydt T,Verellen D,De Ridder M

更新日期：2012-06-01 00:00:00

abstract：:An algorithm, which combines the scanning beam with dynamic collimation to generate any arbitrary intensity profile, is presented. The desired intensity profile is assumed to be piecewise linear. The dynamic collimation method used is the "sliding window." The algorithm can be used either for a given scanning beam pro...

journal_title：Medical physics

authors： Spirou SV,Chui CS

更新日期：1996-01-01 00:00:00

abstract：:The Anisotropic Analytical Algorithm (AAA) of the Varian Eclipse treatment planning system calculates absolute dose for a variety of beam settings including those with an enhanced dynamic wedge (EDW). This algorithm has gone through a number of version updates since it was first released in July 2005. Previous version...

journal_title：Medical physics

authors： Salomons G,Kerr A,Mei X,Patel D

更新日期：2008-07-01 00:00:00

abstract：:Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter-relationship among arc range, Multi-Leaf Collimator (MLC) leaf positions and angular...

journal_title：Medical physics

authors： Oliver M,Chen J,Wong E

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:Several works have recently focused on flattening-filter-free (FFF) beams of linear accelerators of various companies (in particular, Varian and Elekta), but no overview as yet exists for the flattening-filter free 7XU beam (Siemens Artiste). METHODS:Dosimetric properties of the 7XU beam were measured in May a...

journal_title：Medical physics

authors： Dzierma Y,Licht N,Nuesken F,Ruebe C

更新日期：2012-05-01 00:00:00

abstract：PURPOSE:Though failure mode and effects analysis (FMEA) is becoming more widely adopted for risk assessment in radiation therapy, to our knowledge, its output has never been validated against data on errors that actually occur. The objective of this study was to perform FMEA of a stereotactic body radiation therapy (SB...

journal_title：Medical physics

authors： Yang F,Cao N,Young L,Howard J,Logan W,Arbuckle T,Sponseller P,Korssjoen T,Meyer J,Ford E

更新日期：2015-06-01 00:00:00

abstract：:Permanent implants of 125I seeds at Memorial Sloan-Kettering Cancer Center are performed by the method of "dimension averaging" to determine the total activity to be implanted; that is, the activity (in mCi) is taken to be five times the average dimension (in cm) of the target region. A nomograph has recently been dev...

journal_title：Medical physics

authors： Anderson LL

更新日期：1976-01-01 00:00:00

abstract：PURPOSE:To apply the recent code of practice from the IAEA/AAPM, TRS 483, to helical tomotherapy (HT) for reference and relative dosimetry obtaining correction factors for the Exradin A1SL ionization chamber. METHODS:The beam quality correction factor for the A1SL chamber was obtained through three different approache...

journal_title：Medical physics

authors： Lopes MDC,Santos T,Ventura T,Capela M

更新日期：2019-12-01 00:00:00

abstract：:Calibration of an imported strontium-90 ophthalmic applicator at the U.S. National Bureau of Standards (now the National Institute of Standards and Technology) has disclose a significant discrepancy in dose rate calibration (32%-35%) with that quoted by the manufacturer. The University of Wisconsin has investigated th...

journal_title：Medical physics

authors： Goetsch SJ,Sunderland KS

更新日期：1991-03-01 00:00:00

abstract：PURPOSE:To design an efficient method for utilizing phase-space source models in the GPU-based Monte Carlo (MC) dose calculation engine gDPM. METHODS:In GPU-based MC algorithms, particles are transported in parallel on different threads. Particles of different types and energies can require significantly different exe...

journal_title：Medical physics

authors： Townson R,Jia X,Zavgorodni S,Jiang S

更新日期：2012-06-01 00:00:00

abstract：:The photon energy spectrum emanating from a Leksell Gamma Knife, Model 23004B, was measured between 0.250 and 3.5 MeV with the sources exposed. Measurements were made using a 2x2 inch NaI detector enclosed in a lead-shielded apparatus having a 1/4 inch diameter measurement aperture, which reduced the amount of radiati...

journal_title：Medical physics

authors： Drzymala RE,Sohn JW,Guo C,Sobotka LG,Purdy JA

更新日期：2001-04-01 00:00:00

abstract：:The immediate goal of clinically based x-ray-transmission computed tomography (CT) is to provide a measurement of the x-ray linear attenuation coefficient in cross section with the ultimate goal of impacting on patient management and care. To do this with the accuracy needed for clinical goals requires the careful int...

journal_title：Medical physics

authors： McCullough EC,Payne JT

更新日期：1977-03-01 00:00:00

abstract：PURPOSE:To quickly and automatically propagate organ contours from pretreatment to fraction images in magnetic resonance (MR)-guided prostate external-beam radiotherapy. METHODS:Five prostate cancer patients underwent 20 fractions of image-guided external-beam radiotherapy on a 1.5 T MR-Linac system. For each patient,...

journal_title：Medical physics

authors： Eppenhof KAJ,Maspero M,Savenije MHF,de Boer JCJ,van der Voort van Zyp JRN,Raaymakers BW,Raaijmakers AJE,Veta M,van den Berg CAT,Pluim JPW

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:To compare how the inclusion of the uncertainties in dose and optical density affects the results of the calibration of Gafchromic(®) EBT3 radiochromic films. METHODS:Five methods of least square minimization were compared for calibration of radiochromic films. These differed in the way in which the uncertaint...

journal_title：Medical physics

authors： Garcia LI,Azorin JF

更新日期：2013-07-01 00:00:00

abstract：:This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). In particular, the option of producing a therapy beam at an orthogonal direction to the incoming protons is considered. Monte Carlo radiation transport simulations, both with and wit...

journal_title：Medical physics

authors： Allen DA,Beynon TD,Green S

更新日期：1999-01-01 00:00:00