Noise correlations in images acquired simultaneously with a dual-energy sandwich detector.

abstract：PURPOSE:The need for an accurate lesion segmentation tool in 18FDG PET is a prerequisite for the estimation of lesion response to therapy, for radionuclide dosimetry, and for the application of 18FDG PET to radiotherapy planning. In this work, the authors have developed an iterative method based on a mathematical fit d...

journal_title：Medical physics

authors： Nehmeh SA,El-Zeftawy H,Greco C,Schwartz J,Erdi YE,Kirov A,Schmidtlein CR,Gyau AB,Larson SM,Humm JL

更新日期：2009-10-01 00:00:00

abstract：PURPOSE:To formulate convex planning objectives of treatment plan multicriteria optimization with explicit relationships to the dose-volume histogram (DVH) statistics used in plan quality evaluation. METHODS:Conventional planning objectives are designed to minimize the violation of DVH statistics thresholds using pena...

journal_title：Medical physics

authors： Engberg L,Forsgren A,Eriksson K,Hårdemark B

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:The primary feasibility steps of demonstrating the ability of microwave-induced thermoacoustic (TA) in phantoms have been previously reported. However, none were shown to target a diseased site in living subjects in thermoacoustic tomography (TAT) field so far. To determine the expressions of oncogenic surface ...

journal_title：Medical physics

authors： Nie L,Ou Z,Yang S,Xing D

更新日期：2010-08-01 00:00:00

abstract：:The calibration and quality control of compensators is conventionally performed with an ion chamber in a water-equivalent phantom. In our center, the compensator factor and four off-axis fluence ratios are measured to verify the central axis beam modulation and orientation of the compensator. Here we report the invest...

journal_title：Medical physics

authors： Menon GV,Sloboda RS

更新日期：2003-07-01 00:00:00

abstract：PURPOSE:Until recently the treatment verification for patients undergoing fast neutron therapy at our facility was accomplished through a combination of neutron beam portal films aligned with a graticule mounted on an orthronormal x-ray tube. To eliminate uncertainty with respect to the relative positions of the x-ray ...

journal_title：Medical physics

authors： Halford R,Snyder M

更新日期：2012-06-01 00:00:00

abstract：:A detailed Monte Carlo study of the PTW-diamond solid state detector response in megavoltage photon beams (60Co gamma rays to 25 MV x rays) has been performed with the EGS4 Monte Carlo Code. The sensitive volume of the diamond detector is a disk of diameter 4.4 mm and thickness 0.40 mm. The phantom material was water ...

journal_title：Medical physics

authors： Mobit PN,Sandison GA

更新日期：1999-11-01 00:00:00

abstract：PURPOSE:The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. METHODS:The effective range, deflectio...

journal_title：Medical physics

authors： Leung MK,Chow JC,Chithrani BD,Lee MJ,Oms B,Jaffray DA

更新日期：2011-02-01 00:00:00

abstract：PURPOSE:The purpose of this study was to investigate the impact of transverse magnetic fields on the dose response of a radiophotoluminescent glass dosimeter (RGD) in megavoltage photon beams. METHODS:The RGD relative response (i.e., RGD dose per absorbed dose to water at the midpoint of the detector in the absence of...

journal_title：Medical physics

authors： Ito S,Araki F,Ohno T

更新日期：2020-04-01 00:00:00

abstract：:A computer dose model for a low energy gamma-emitting stent in a heterogeneous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distribution about filtered gamma sources (Sievert-DPK model). The new gamma stent model can take into a...

journal_title：Medical physics

authors： Janicki C,Duggan DM,Rahdert DA

更新日期：2001-07-01 00:00:00

abstract：PURPOSE:Dose verification in highly conformal radiation therapy such as IMRT or proton therapy can benefit from the high spatial resolution offered by radio-chromic films such as Gafchromic EBT or EBT2. Recently, a new generation of these films, EBT3, has become available. The composition and thickness of the sensitive...

journal_title：Medical physics

authors： Reinhardt S,Hillbrand M,Wilkens JJ,Assmann W

更新日期：2012-08-01 00:00:00

abstract：:A prototype Emission-Transmission Computed Tomography (ETCT) system is being developed that will acquire single-slice x-ray transmission CT images simultaneously with single photon emission computed tomography (SPECT) images. This system will permit the correlation of anatomical information from x-ray CT with function...

journal_title：Medical physics

authors： Liew SC,Hasegawa BH

更新日期：1991-09-01 00:00:00

abstract：PURPOSE:Water equivalent diameter (WED) is the preferred surrogate for patient size in CT. It is better than geometric size surrogates and patient weight/height/BMI/age because it correlates the best with x-ray attenuation. The administration of oral/IV contrast agents increases a patient's attenuation and should there...

journal_title：Medical physics

authors： Viggiano B,Rose S,Szczykutowicz TP

更新日期：2021-01-13 00:00:00

abstract：:Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared wit...

journal_title：Medical physics

authors： Prisciandaro JI,Frechette CM,Herman MG,Brown PD,Garces YI,Foote RL

更新日期：2004-11-01 00:00:00

abstract：PURPOSE:Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is correc...

journal_title：Medical physics

authors： Tornero-López AM,Guirado D,Perez-Calatayud J,Ruiz-Arrebola S,Simancas F,Gazdic-Santic M,Lallena AM

更新日期：2013-12-01 00:00:00

abstract：PURPOSE:High-dose-rate brachytherapy (HDR-BT) is a treatment option for malignant skin diseases compared to external beam radiation therapy, HDR-BT provides improved target coverage, better organ sparing, and has comparable treatment times. This is especially true for large clinical targets with complex topologies. To ...

journal_title：Medical physics

authors： Guthier CV,Devlin PM,Harris TC,O'Farrell DA,Cormack RA,Buzurovic I

更新日期：2020-03-01 00:00:00

abstract：PURPOSE:To evaluate the energy dependence of Gafchromic EBT3 film for establishing a quality assurance method of bolus electron conformal radiotherapy. METHODS:We irradiated electron beam to EBT3 films, which were set in the water tank. The linear accelerator used was Varian Clinac 21EX. The energy of electron beams w...

journal_title：Medical physics

authors： Inoue T,Sugimoto S,Fukata K,Kurokawa C,Ozawa S,Sasai K

更新日期：2012-06-01 00:00:00

abstract：:Computed tomography is sensitive to changes in the imaged distribution during acquisition of the projection data. Previous investigations have emphasized discrete or discontinuous changes in the imaged object. Recent advances have motivated our investigation of object time-dependence characterized by a continuous func...

journal_title：Medical physics

authors： Holden JE,Ip WR

更新日期：1978-11-01 00:00:00

abstract：:The purposes of this research are to investigate the effectiveness of our novel image features for segmentation of anatomic regions such as the lungs and the mediastinum in chest radiographs and to develop an automatic computerized method for image processing. A total of 85 screening chest radiographs from Johns Hopki...

journal_title：Medical physics

authors： Tsujii O,Freedman MT,Mun SK

更新日期：1998-06-01 00:00:00

abstract：:The half-life of two I-125 encapsulated clinical seeds was measured with a Si(Li) semiconductor detector. Two measurements of each seed yielded an average half-life of 59.56 +/- 0.17 days. The results are discussed in terms of the influence of possible I-126 contamination and leakage of I-125 activity through encapsul...

journal_title：Medical physics

authors： Kubo H

更新日期：1983-11-01 00:00:00

abstract：:A beam intensity monitor was tested in a 230-MeV proton beam at the Loma Linda Proton Therapy Accelerator during its commissioning at Fermi National Accelerator Laboratory. The intensity monitor was designed to regulate the beam intensity extracted from the proton synchrotron. The proton beam is tunable between 70 and...

journal_title：Medical physics

authors： Coutrakon G,Miller D,Kross BJ,Anderson DF,DeLuca P Jr,Siebers J

更新日期：1991-07-01 00:00:00

abstract：:The intensity of Compton scattered photons is directly proportional to the electron density of a substance; therefore it is possible to detect changes in electron density by this noninvasive method. The source-detector geometry has been varied to study the effects of geometry on the calculated electron density values,...

journal_title：Medical physics

authors： Huddleston AL,Sackler JP

更新日期：1985-01-01 00:00:00

abstract：:Accurately assessing the quality of prostate brachytherapy intraoperatively would be valuable for improved clinical outcome by ensuring the delivery of a prescribed tumoricidal radiation dose to the entire prostate gland. One necessary step towards this goal is the robust and rapid localization of implanted seeds. Sev...

journal_title：Medical physics

authors： Tutar IB,Managuli R,Shamdasani V,Cho PS,Pathak SD,Kim Y

更新日期：2003-12-01 00:00:00

abstract：PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

journal_title：Medical physics

authors： Li T,Li X,Yang Y,Heron DE,Huq MS

更新日期：2010-12-01 00:00:00

abstract：:Monte Carlo (MC) techniques can be used to build a simulation model of an electron accelerator to calculate output factors for electron fields. This can be useful during commissioning of electron beams from a linac and in clinical practice where irregular fields are also encountered. The Monte Carlo code BEAM/EGS4 was...

journal_title：Medical physics

authors： Verhaegen F,Mubata C,Pettingell J,Bidmead AM,Rosenberg I,Mockridge D,Nahum AE

更新日期：2001-06-01 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：:It has recently been shown that longitudinal aliasing can be a significant and detrimental presence in reconstructed single-slice helical computed tomography (CT) volumes. This aliasing arises because the directly measured data in helical CT are generally undersampled by a factor of at least 2 in the longitudinal dire...

journal_title：Medical physics

authors： La Rivière PJ,Pan X

更新日期：2001-03-01 00:00:00

abstract：:Transmission imaging is receiving increasing attention in SPECT due to the need to compensate for nonuniform attenuation in cardiac-chest SPECT. The quality of a transmission image has an important effect on the measured attenuation distribution. To improve image quality, knowledge of the performance characteristics o...

journal_title：Medical physics

authors： Cao Z,Tsui BM

更新日期：1992-09-01 00:00:00

abstract：:The purpose of this paper is to determine the correlation between dose-volume histogram (DVH) and dose wall-histogram (DWH) in the evaluation of rectal complications for prostate cancer patients treated with three-dimensional conformal radiotherapy (3D-CRT). A retrospective analysis of DVHs and DWHs of a subset of 25 ...

journal_title：Medical physics

authors： García-Vicente F,Zapatero A,Floriano A,Cruz-Conde A,Perez L,Marín A,Mínguez C,Torres JJ

更新日期：2005-08-01 00:00:00

abstract：PURPOSE:The study aims to investigate whether Nakagami parameters--estimated from the statistical distribution of the backscattered ultrasound radio-frequency (RF) signals--could provide a means for quantitative characterization of parotid-gland injury resulting from head-and-neck radiotherapy. METHODS:A preliminary c...

journal_title：Medical physics

authors： Yang X,Tridandapani S,Beitler JJ,Yu DS,Wu N,Wang Y,Bruner DW,Curran WJ,Liu T

更新日期：2014-02-01 00:00:00

abstract：BACKGROUND:The rapid development and complexity of new x-ray computed tomography (CT) technologies and the need for evidence-based optimization of image quality with respect to radiation and contrast media dose call for an updated approach towards CT performance evaluation. AIMS:This report offers updated testing guid...

journal_title：Medical physics

authors： Samei E,Bakalyar D,Boedeker KL,Brady S,Fan J,Leng S,Myers KJ,Popescu LM,Ramirez Giraldo JC,Ranallo F,Solomon J,Vaishnav J,Wang J

更新日期：2019-11-01 00:00:00