Postal intercomparison of absorbed dose for high energy x rays with thermoluminescence dosimeters.

abstract：:Proton therapy offers the potential for excellent dose conformity and reduction in integral dose. The superior dose distribution is, however, much more sensitive to changes in radiological depths along the beam path than for photon fields. Respiratory motion can cause such changes for treatments sites like lung, liver...

journal_title：Medical physics

authors： Lu HM,Brett R,Sharp G,Safai S,Jiang S,Flanz J,Kooy H

更新日期：2007-08-01 00:00:00

abstract：PURPOSE:Multiple commercial, open-source, and academic software tools exist for objective quantification of lung density in computed tomography (CT) images. The purpose of this study was to evaluate the intersoftware reproducibility of CT lung density measurements. METHODS:Computed tomography images from 50 participan...

journal_title：Medical physics

authors： Kirby M,Hatt C,Obuchowski N,Humphries SM,Sieren J,Lynch DA,Fain SB,QIBA Lung Density Committee.

更新日期：2020-07-01 00:00:00

abstract：PURPOSE:One limitation of positron emission tomography (PET) imaging of the torso is patient motion. Motion-compensated image reconstruction (MCIR) is one method employed to reduce the deleterious effects of motion. Existing MCIR algorithms use a single sensitivity correction term, which provides inexact normalization ...

journal_title：Medical physics

authors： Dikaios N,Fryer TD

更新日期：2011-09-01 00:00:00

abstract：:A direct data link between a CT scanner and a radiation treatment planning system has been developed. The link transmits the data serially over a coaxial cable using the pseudo-paper-tape punch and reader (serial PIO) interfaces. The data transmission rate with error-check is approximately 25,000 8-bit bytes/s. This t...

journal_title：Medical physics

authors： Abel RN,Buhler LA,Chu WT,Slater JM,Neilsen IR,Zimmerman DC

更新日期：1979-09-01 00:00:00

abstract：PURPOSE:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system ...

journal_title：Medical physics

authors： Mendez I,Hartman V,Hudej R,Strojnik A,Casar B

更新日期：2013-01-01 00:00:00

abstract：PURPOSE:Previous studies have shown atlas-based segmentation using a single best matched (SBM) atlas subject can significantly reduce contouring time. A new multi-atlas approach has been shown to provide greater accuracy than SBM for cancer of the head and neck. The goal of this study was to evaluate the multi-atlas te...

journal_title：Medical physics

authors： Pirozzi S,Horvat M,Piper J,Nelson A

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:An original radionuclide calibrator method for activity determination is presented. The method could be used for intercomparison surveys for short half-life radioactive sources used in Nuclear Medicine, such as(99m)Tc or most positron emission tomography radiopharmaceuticals. METHODS:By evaluation of the resul...

journal_title：Medical physics

authors： Oliveira PA,Santos JA

更新日期：2014-07-01 00:00:00

abstract：PURPOSE:In medical imaging, data scaling is sometimes desired to handle the system complexity, such as uniformity calibration. Since the data are usually saved in short integer, conventional data scaling will first scale the data in floating point format and then truncate or round the floating point data to short integ...

journal_title：Medical physics

authors： Bai C,Conwell R,Kindem J

更新日期：2010-06-01 00:00:00

abstract：PURPOSE:This work introduces a rigid registration framework for patient positioning in radiotherapy, based on real-time surface acquisition by a time-of-flight (ToF) camera. Dynamic properties of the system are also investigated for future gating/tracking strategies. METHODS:A novel preregistration algorithm, based on...

journal_title：Medical physics

authors： Placht S,Stancanello J,Schaller C,Balda M,Angelopoulou E

更新日期：2012-01-01 00:00:00

abstract：PURPOSE:Respiration-induced intrafraction target motion is a concern in liver cancer radiotherapy, especially in stereotactic body radiotherapy (SBRT), and therefore, verification of its motion is necessary. An effective means to localize the liver cancer is to insert metal fiducial markers to or near the tumor with si...

journal_title：Medical physics

authors： Park JC,Park SH,Kim JH,Yoon SM,Kim SS,Kim JS,Liu Z,Watkins T,Song WY

更新日期：2011-02-01 00:00:00

abstract：PURPOSE:This work investigates the energy response and dose-response curve determinations for XR-QA2 radiochromic film dosimetry system used for synchrotron radiation work and for quality assurance in diagnostic radiology, in the range of effective energies 18-46.5 keV. METHODS:Pieces of XR-QA2 films were irradiated, ...

journal_title：Medical physics

authors： Di Lillo F,Mettivier G,Sarno A,Tromba G,Tomic N,Devic S,Russo P

更新日期：2016-01-01 00:00:00

abstract：:Dose uniformity throughout the treatment volume is essential to precision radiation therapy. Tissue compensators are often used as a means to eliminate dose nonuniformity resulting from surface contour irregularities. This paper evaluates the accuracy of using an effective attenuation coefficient for calculating the t...

journal_title：Medical physics

authors： Bagne FR,Samsami N,Hoke SW,Bronn DG

更新日期：1990-01-01 00:00:00

abstract：PURPOSE:The spatial and temporal tracking performance of a commercially available 3D optical surface imaging system is evaluated for its potential use in frameless stereotactic radiosurgery head tracking applications. METHODS:Both 3D surface and infrared (IR) marker tracking were performed simultaneously on a head pha...

journal_title：Medical physics

authors： Wiersma RD,Tomarken SL,Grelewicz Z,Belcher AH,Kang H

更新日期：2013-11-01 00:00:00

abstract：PURPOSE:The research is to develop a novel CNN-based adversarial deep learning method to improve and expedite the multi-organ semantic segmentation of CT images and to generate accurate contours on pelvic CT images. METHODS:Planning CT and structure datasets for 120 patients with intact prostate cancer were retrospect...

journal_title：Medical physics

authors： Zhang Z,Zhao T,Gay H,Zhang W,Sun B

更新日期：2020-11-05 00:00:00

abstract：PURPOSE:External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam. A hi...

journal_title：Medical physics

authors： Barbés B,Azcona JD,Burguete J,Martí-Climent JM

更新日期：2014-01-01 00:00:00

abstract：:This study proposes an algorithm for selecting beam weight, wedge angle, and wedge orientation for three-dimensional radiation therapy treatment planning. According to dose gradient analysis, the necessary and sufficient condition for achieving a homogeneous dose over the target volume is that the total vector sum of ...

journal_title：Medical physics

authors： Dai J,Zhu Y

更新日期：2000-08-01 00:00:00

abstract：PURPOSE:To determine the accuracy and reproducibility of the automatic- setup procedure of a 3D water scanner (3D SCANNER, Sun Nuclear Corp). The procedure automatically aligns the scanner's coordinate system to the Linac coordinate system. A unique off-center detector holder extends the scan range to 630 mm, eliminati...

journal_title：Medical physics

authors： Li J,Lu B,Yan G,Huang Y,Liu C

更新日期：2012-06-01 00:00:00

abstract：:This study evaluates the effects of respiratory motion on breast radiotherapy delivered using segmented multileaf collimator (SMLC) intensity modulation. An anthropomorphic breast phantom was constructed of polystyrene plates between which radiographic films were inserted. The phantom was mounted on a moving platform ...

journal_title：Medical physics

authors： Liu Q,McDermott P,Burmeister J

更新日期：2007-01-01 00:00:00

abstract：PURPOSE:This report describes upgrades and performance characterization of an experimental benchtop cone-beam x-ray fluorescence computed tomography (XFCT) system capable of determining the spatial distribution and concentration of metal probes such as gold nanoparticles (GNPs). Specifically, a high-power (~3 kW) indus...

journal_title：Medical physics

authors： Manohar N,Reynoso FJ,Cho SH

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:To validate a delivery quality assurance (DQA) protocol for tomotherapy based on the measurement of the leaf open times (LOTs). In addition, to show the correlation between the mean relative LOT discrepancy and the dose deviation in the planning target volume (PTV). MATERIALS AND METHODS:We used a LOT measurem...

journal_title：Medical physics

authors： Schopfer M,Bochud FO,Bourhis J,Moeckli R

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. METHODS:Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was...

journal_title：Medical physics

authors： Hoppe ME,Schmidt TG

更新日期：2012-06-01 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:To develop a novel three-dimensional (3D) hybrid-encoding framework using compressed sensing (CS) and Toeplitz encoding with variable phase-scrambled radio-frequency (RF) excitation, which has the following advantages: low power deposition of RF pulses, reduction of the signal dynamic range, no additional hardw...

journal_title：Medical physics

authors： Wang H,Liang D,Su S,King KF,Chang Y,Liu X,Zheng H,Ying L

更新日期：2020-04-01 00:00:00

abstract：PURPOSE:To determine the diagnostic efficacy of optical coherence tomography (OCT) to identify cervical intraepithelial neoplasia (CIN) grade 2 or higher by computer-aided diagnosis (CADx). METHODS:OCT has been investigated as a screening/diagnostic tool in the management of preinvasive and early invasive cancers of t...

journal_title：Medical physics

authors： Kang W,Qi X,Tresser NJ,Kareta M,Belinson JL,Rollins AM

更新日期：2011-01-01 00:00:00

abstract：PURPOSE:The lateral edge of a proton therapy beam is commonly used to achieve conformality to the treatment volume where critical structures reside close to the target. However, when treating shallow depths, the lateral edge of a pencil beam scanning (PBS) system may be broader than that of a double scattered (DS) syst...

journal_title：Medical physics

authors： Charlwood FC,Aitkenhead AH,Mackay RI

更新日期：2016-03-01 00:00:00

abstract：PURPOSE:To implement the DMAIC (Define-Measure-Analyze-Improve-Control) can be used for customizing the patient-specific QA by designing site-specific range tolerances. METHODS:The DMAIC framework (process flow diagram, cause and effect, Pareto chart, control chart, and capability analysis) were utilized to determine ...

journal_title：Medical physics

authors： Rah JE,Shin D,Manger RP,Kim TH,Oh DH,Kim DY,Kim GY

更新日期：2018-02-01 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 optimum x-ray spectra for acquisition of digital mammographic images using an amorphous selenium (a-Se) photoconductor are investigated. The recorded images consist of latent charge distributions on the surface of an a-Se plate, which are then read out using two methods, laser discharge, or flat panel recharge. Th...

journal_title：Medical physics

authors： Fahrig R,Rowlands JA,Yaffe MJ

更新日期：1996-04-01 00:00:00

abstract：PURPOSE:The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor. METHODS:The authors ...

journal_title：Medical physics

authors： Badano A,Wang J,Boynton P,Le Callet P,Cheng WC,Deroo D,Flynn MJ,Matsui T,Penczek J,Revie C,Samei E,Steven PM,Swiderski S,Van Hoey G,Yamaguchi M,Hasegawa M,Nagy BV

更新日期：2016-07-01 00:00:00

abstract：PURPOSE:To construct a Monte Carlo (MC)-based simulation model for analyzing the dependence of tumor oxygen distribution on different variables related to tumor vasculature [blood velocity, vessel-to-vessel proximity (vessel proximity), and inflowing oxygen partial pressure (pO2)]. METHODS:A voxel-based tissue model c...

journal_title：Medical physics

authors： Lagerlöf JH,Kindblom J,Bernhardt P

更新日期：2014-09-01 00:00:00