Use of simulated annealing for optimization of alignment parameters in limited MRI acquisition volumes of the brain.

abstract：:The bremsstrahlung spectrum from an 8-MeV linear accelerator has been measured using a NaI(T1) spectrometer system. The spectrum shows a low-energy cutoff at 0.4 MeV and the maximum photon energy to be approximately 6% greater than the nominal energy. The maximum emission of energy fluence was 1.6 and 1.8 MeV for meas...

journal_title：Medical physics

authors： Levy LB,Waggener RG,Wright AE

更新日期：1976-05-01 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：:One limitation to the widespread implementation of Monte Carlo (MC) patient dose-calculation algorithms for radiotherapy is the lack of a general and accurate source model of the accelerator radiation source. Our aim in this work is to investigate the sensitivity of the photon-beam subsource distributions in a MC sour...

journal_title：Medical physics

authors： Fix MK,Keall PJ,Siebers JV

更新日期：2005-04-01 00:00:00

abstract：PURPOSE:The hematopoietically active tissues of skeletal bone marrow are a prime target for computational dosimetry given potential risks of leukemia and, at higher dose levels, acute marrow toxicity. The complex three-dimensional geometry of trabecular spongiosa, however, complicates schema for dose assessment in such...

journal_title：Medical physics

authors： Geyer AM,Schwarz BC,Hobbs RF,Sgouros G,Bolch WE

更新日期：2017-01-01 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：:A slat collimator in single photon emission computed tomography consists of a set of parallel slats. As the collimator spins, the detector measures a one-dimensional projection data set. A complete data set can be obtained by rotating the detector/collimator assembly around the object (patient) while the collimator sp...

journal_title：Medical physics

authors： Zeng GL,Gagnon D,Matthews CG,Kolthammer JA,Radachy JD,Hawkins WG

更新日期：2002-07-01 00:00:00

abstract：PURPOSE:In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts in CBCT images. Such gain variations can be caused by change in detector entrance exposure levels or beam hardening, and they are not accou...

journal_title：Medical physics

authors： Altunbas C,Lai CJ,Zhong Y,Shaw CC

更新日期：2014-09-01 00:00:00

abstract：OBJECTIVE:Carbon ion particle therapy delivers sharp Bragg's peaks, and hence can produce dose delivery of very high precision and conformality. To complement this characteristic, particle therapy centers implement a number of technologies unique to these centers, and are not commonly known to the medical physics commu...

journal_title：Medical physics

authors： Cernica G,Mun S

更新日期：2012-06-01 00:00:00

abstract：:In this paper we examine the few-view reconstruction problem as it applies to imaging vascular trees. A fully automated reconstruction algorithm is described that circumvents the traditional "correspondence problem," using only notions of consistency and connectivity. It is assumed that the vascular tree is a connecte...

journal_title：Medical physics

authors： Henri CJ,Peters TM

更新日期：1996-02-01 00:00:00

abstract：PURPOSE:The aim of this paper is to investigate the accuracy of a laser∕camera surface imaging system (Sentinel) when used on patients treated in the thorax or pelvic regions and to evaluate system employment conditions and patient setup procedures that provide more accurate results. METHODS:The system was tested on t...

journal_title：Medical physics

authors： Pallotta S,Simontacchi G,Marrazzo L,Ceroti M,Paiar F,Biti G,Bucciolini M

更新日期：2013-01-01 00:00:00

abstract：PURPOSE:The purpose of this study is to estimate the effect of edema, developed during implant procedure, on tumor cell surviving fraction(SF) and tumor control probability(TCP) in the patients of prostate cancer who underwent 131 Cs permanent seed implants. METHODS:The impact of edema on SF and TCP, was calculated us...

journal_title：Medical physics

authors： Kehwar TS,Huq MS,Smith RP

更新日期：2012-06-01 00:00:00

abstract：:Current MRI nonuniformity correction techniques are reviewed and investigated. Many approaches are used to remedy this artifact, but it is not clear which method is the most appropriate in a given situation, as the applications have been with different MRI coils and different clinical applications. In this work four w...

journal_title：Medical physics

authors： Velthuizen RP,Heine JJ,Cantor AB,Lin H,Fletcher LM,Clarke LP

更新日期：1998-09-01 00:00:00

abstract：:A method to significantly reduce the exposure area product in fluoroscopy using a pre-patient region-of-interest (ROI) attenuator is presented. The attenuator has a thin central region and a gradually increasing thickness away from the center. It is shown that the unwanted brightening artifact caused by the attenuator...

journal_title：Medical physics

authors： Robert N,Komljenovic PT,Rowlands JA

更新日期：2002-05-01 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：PURPOSE:Obtaining an integral depth-dose (IDD) curve using a recently developed acrylic-disk radiation sensor (ADRS) is time-consuming because its single structure requires point-by-point measurements in a water phantom. The goal of this study was to verify the ability of a newly designed multilayer ADRS, composed of 2...

journal_title：Medical physics

authors： Son J,Shin D,Kim T,Park S,Rah JE

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:Tomosynthesis is a promising modality for breast imaging. The appearance of the tomosynthesis reconstructed image is greatly affected by the choice of acquisition and reconstruction parameters. The purpose of this study was to investigate the limitations of tomosynthesis breast imaging due to scan parameters an...

journal_title：Medical physics

authors： Reiser I,Nishikawa RM

更新日期：2010-04-01 00:00:00

abstract：:An addendum to the AAPM's TG-51 protocol for the determination of absorbed dose to water in megavoltage photon beams is presented. This addendum continues the procedure laid out in TG-51 but new kQ data for photon beams, based on Monte Carlo simulations, are presented and recommendations are given to improve the accur...

journal_title：Medical physics

authors： McEwen M,DeWerd L,Ibbott G,Followill D,Rogers DW,Seltzer S,Seuntjens J

更新日期：2014-04-01 00:00:00

abstract：PURPOSE:Monitoring of physiological parameters is a major concern in Intensive Care Units (ICU) given their role in the assessment of vital organ function. Within this context, one issue is the lack of efficient noncontact techniques for respiratory monitoring. In this paper, we present a novel noncontact solution for ...

journal_title：Medical physics

authors： Nazir S,Pateau V,Bert J,Clement JF,Fayad H,l'Her E,Visvikis D

更新日期：2020-10-28 00:00:00

abstract：:Using superior localization and immobilization methods, stereotactic radiosurgery is capable of delivering spheres of dose as small as a few millimetres in diameter to intracranial targets. For targets abutting critical structures, the most conformal treatments minimize adverse radiation side effects and it is importa...

journal_title：Medical physics

authors： Keller BM,Peressotti C,Pignol JP

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:For almost four decades bead and wire ramps have been used in the evaluation of slice width as part of QA testing for CT scanners. While each of these approaches have been recognized and accepted as reliable, in this paper we investigate the differences, advantages and limitations of these tools. Moreover, we s...

journal_title：Medical physics

authors： Marteinsdóttir M,Olafsdottir H,Fredriksson J,Andresson A,Healy A,Kristbjornsson A,Kristinsson S,Levy J,Goodenough D

更新日期：2012-06-01 00:00:00

abstract：:Multimodality NIR spectroscopy systems offer the possibility of region-based vascular and molecular characterization of tissue in vivo. However, computationally efficient 3D image reconstruction algorithms specific to these image-guided systems currently do not exist. Image reconstruction is often based on finite-elem...

journal_title：Medical physics

authors： Srinivasan S,Pogue BW,Carpenter C,Yalavarthy PK,Paulsen K

更新日期：2007-11-01 00:00:00

abstract：PURPOSE:Periodic MV∕KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging do...

journal_title：Medical physics

authors： Zhang P,Hunt M,Happersett L,Cox B,Mageras G

更新日期：2012-09-01 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

authors： Vedantham S,Karellas A,Suryanarayanan S,Levis I,Sayag M,Kleehammer R,Heidsieck R,D'Orsi CJ

更新日期：2000-08-01 00:00:00

abstract：:The physical imaging performance of ST-V, ST-VA, and ST-VN computed radiography image plates, read with a Philips AC3 acquisition system, was investigated at 70 kVp with 0.5 mm of copper beam filtration for four different entrance air kerma values: 0.5, 2.6, 26, and 260 micro Gy. Measurements included characteristic r...

journal_title：Medical physics

authors： Kengyelics SM,Davies AG,Cowen AR

更新日期：1998-11-01 00:00:00

abstract：PURPOSE:The overall goal of this work is to improve the computed tomography (CT) image quality for patients with metal implants or fillings by completing the missing kilovoltage (kV) projection data with selectively acquired megavoltage (MV) data that do not suffer from photon starvation. When both of these imaging sys...

journal_title：Medical physics

authors： Wu M,Keil A,Constantin D,Star-Lack J,Zhu L,Fahrig R

更新日期：2014-12-01 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

authors： Garnica-Garza HM

更新日期：2018-02-01 00:00:00

abstract：:The focal spot of a linear accelerator is often considered to have a fully stable position. In practice, however, the beam control loop of a linear accelerator needs to stabilize after the beam is turned on. As a result, some motion of the focal spot might occur during the start-up phase of irradiation. When acquiring...

journal_title：Medical physics

authors： Sonke JJ,Brand B,van Herk M

更新日期：2003-06-01 00:00:00

abstract：PURPOSE:A 3-year project called LABSYNC has been recently funded by the European Commission, with the aim of designing a radiation facility based on a compact light source, i.e., a laboratory-sized commercial synchrotron, capable of accelerating electrons up to 6 or 20 MeV. An accurate spectral description of hard x ra...

journal_title：Medical physics

authors： Marziani M,Taibi A,Di Domenico G,Gambaccini M

更新日期：2009-10-01 00:00:00

abstract：:An automated data-acquisition and analysis system has been developed for dosimetry measurements on the pion therapy beam at the Clinton P. Anderson Meson Physics Facility Biomedical Channel in Los Alamos using a PDP-11/45 computer and CAMAC interface. Initialization, test, and monitor programs allow the user to set th...

journal_title：Medical physics

authors： Rosen I,Smith A,Lane R,Kelsey C,Lake D,Hogstrom K,Somers J,Helland J,Kittell R,Amols H,Bradbury J,Richman C

更新日期：1978-03-01 00:00:00

abstract：PURPOSE:Concurrent irradiation of the prostate and pelvic lymph nodes is technically challenging due to treating one moving target and one immobile target. The purposes of this article are to propose a new management strategy and to compare this strategy to the conventional isocenter shift method and the previously pro...

journal_title：Medical physics

authors： Xia P,Qi P,Hwang A,Kinsey E,Pouliot J,Roach M 3rd

更新日期：2010-09-01 00:00:00