The determination of electron density by the dual-energy Compton scatter method.

abstract：PURPOSE:The fundamental nature of positron emission tomography (PET), as an event detection system, provides some flexibility for data handling, including retrospective data manipulation. The reorganization of acquisition data allows the emulation of new scans arising from identical radiotracer spatial distributions, b...

journal_title：Medical physics

authors： Schaefferkoetter J,Nai YH,Reilhac A,Townsend DW,Eriksson L,Conti M

更新日期：2019-06-01 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：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：:Current edge detection methods used to determine coronary artery dimensions from digital (DSA) images suffer a strong dependence on the system's modulation transfer function (MTF). The videodensitometric algorithms are less sensitive to MTF blurring, yet still result in an overestimation of the vessel size of 10% to 2...

journal_title：Medical physics

authors： Weber DM

更新日期：1989-03-01 00:00:00

abstract：PURPOSE:Magnetic resonance imaging (MRI) is increasingly used for radiotherapy target delineation, image guidance, and treatment response monitoring. Recent studies have shown that an entire external x-ray radiotherapy treatment planning (RTP) workflow for brain tumor or prostate cancer patients based only on MRI refer...

journal_title：Medical physics

authors： Koivula L,Wee L,Korhonen J

更新日期：2016-08-01 00:00:00

abstract：:The most favorable treatment for moving body anatomy should aim at utilizing organ motion to minimize the dose to sensitive structures without compromising the dose delivered to the target. The solution of the problem of appropriate intensity redistribution over different phases of body motion is achievable in dynamic...

journal_title：Medical physics

authors： Papiez L,McMahon R,Timmerman R

更新日期：2007-12-01 00:00:00

abstract：:The effects of small cavities on dose in water and the dose in a homogeneous nonunit density medium illustrate that inhomogeneities do not act independently in photon dose perturbation, and serve as two constraints which should be satisfied by approximate methods of computed tomography (CT) pixel-based dose calculatio...

journal_title：Medical physics

authors： Wong JW,Henkelman RM

更新日期：1983-03-01 00:00:00

abstract：:Results of an 18-alternative forced-choice experiment have shown that observers were capable of detecting a signal with a contrast of 1 in terms of 10-bit data which were displayed on a CRT monitor with an 8-bit video generator and a window width setting of 1024. We investigated the conditions under which 10-bit signa...

journal_title：Medical physics

authors： Giger ML,Ohara K,Doi K

更新日期：1986-05-01 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 assess current education, practices, attitudes, and perceptions pertaining to ethics and professionalism in medical physics. METHODS:A link to a web-based survey was distributed to the American Association of Physicists in Medicine (AAPM) e-mail membership list, with a follow-up e-mail sent two weeks later....

journal_title：Medical physics

authors： Ozturk N,Armato SG 3rd,Giger ML,Serago CF,Ross LF

更新日期：2013-04-01 00:00:00

abstract：PURPOSE:Intensity-modulated proton therapy (IMPT) is known to be sensitive to patient setup and range uncertainty issues. Multiple robust optimization methods have been developed to mitigate the impact of these uncertainties. Here, we propose a new robust optimization method, which provides an alternative way of robust...

journal_title：Medical physics

authors： Shan J,Sio TT,Liu C,Schild SE,Bues M,Liu W

更新日期：2019-01-01 00:00:00

abstract：:Postoperative beta-irradiation after pterygium excision has been considered a valuable therapeutic procedure to reduce the recurrence rate. Recently, it was reported that beta-irradiation also substantially reduced the risk of surgical failure after glaucoma surgery. Pure beta-irradiation using a 90Sr/Y applicator has...

journal_title：Medical physics

authors： Park YK,Ye SJ,Kim IH,Wee WR,Kim MK,Han HS,Son KJ,Park UJ

更新日期：2008-05-01 00:00:00

abstract：PURPOSE:Modulated electron radiation therapy (MERT) can offer significant advantages for breast treatments over conventional radiotherapy in terms of sparing distal critical structures. While intensity modulated radiation therapy (IMRT) has the advantage of achieving better dose homogeneity inside the target combining ...

journal_title：Medical physics

authors： Eldib A,Li J,Jin L,Ma C

更新日期：2012-06-01 00:00:00

abstract：:Deformable registration is needed for a variety of tasks in establishing the voxel correspondence between respiratory phases. Most registration algorithms assume or imply that the deformation field is smooth and continuous everywhere. However, the lungs are contained within closed invaginated sacs called pleurae and a...

journal_title：Medical physics

authors： Wu Z,Rietzel E,Boldea V,Sarrut D,Sharp GC

更新日期：2008-02-01 00:00:00

abstract：PURPOSE:The authors describe the integration of optical imaging with a targeted small animal irradiator device, focusing on design, instrumentation, 2D to 3D image registration, 2D targeting, and the accuracy of recovering and mapping the optical signal to a 3D surface generated from the cone-beam computed tomography (...

journal_title：Medical physics

authors： Weersink RA,Ansell S,Wang A,Wilson G,Shah D,Lindsay PE,Jaffray DA

更新日期：2014-10-01 00:00:00

abstract：:The visual observer performance for detecting low-contrast patterns by employing both the receiver operating characteristic (ROC) and the 9-alternative forced choice (9-AFC) method is investigated. For each observer and each experimental technique, the results were reproducible with respect to a repeated observation. ...

journal_title：Medical physics

authors： Herrmann C,Buhr E,Hoeschen D,Fan SY

更新日期：1993-05-01 00:00:00

abstract：PURPOSE:In this study the Octavius detector 729 ionization chamber (IC) array with the Octavius 4D phantom was characterized for flattening filter (FF) and flattening filter free (FFF) static and rotational beams. The device was assessed for verification with FF and FFF RapidArc treatment plans. METHODS:The response o...

journal_title：Medical physics

authors： McGarry CK,O'Connell BF,Grattan MW,Agnew CE,Irvine DM,Hounsell AR

更新日期：2013-09-01 00:00:00

abstract：PURPOSE:The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in ...

journal_title：Medical physics

authors： Edelhoff D,Walczak L,Frank F,Heil M,Schmitz I,Weichert F,Suter D

更新日期：2015-10-01 00:00:00

abstract：PURPOSE:Accurate calculation of proton stopping power ratio (SPR) relative to water is crucial to proton therapy treatment planning, since SPR affects prediction of beam range. Current standard practice derives SPR using a single CT scan. Recent studies showed that dual-energy CT (DECT) offers advantages to accurately ...

journal_title：Medical physics

authors： Shen C,Li B,Chen L,Yang M,Lou Y,Jia X

更新日期：2018-04-01 00:00:00

abstract：:Two experimental methods are described for obtaining average energies of neutron spectra produced by an electron accelerator in a medical treatment room. In the first method, the dose equivalent is measured by means of indium activation foils in an Andersson-Braun moderator. Fluences are determined by the usual activa...

journal_title：Medical physics

authors： LaRiviere PD

更新日期：1985-11-01 00:00:00

abstract：:Bioluminescent imaging (BLI) of luciferase-expressing cells in live small animals is a powerful technique for investigating tumor growth, metastasis, and specific biological molecular events. Three-dimensional imaging would greatly enhance applications in biomedicine since light emitting cell populations could be unam...

journal_title：Medical physics

authors： Slavine NV,Lewis MA,Richer E,Antich PP

更新日期：2006-01-01 00:00:00

abstract：PURPOSE:The Imaging and Radiation Oncology Core Houston (IROC-H) (formerly the Radiological Physics Center) has reported varying levels of agreement in their anthropomorphic phantom audits. There is reason to believe one source of error in this observed disagreement is the accuracy of the dose calculation algorithms an...

journal_title：Medical physics

authors： Faught AM,Davidson SE,Fontenot J,Kry SF,Etzel C,Ibbott GS,Followill DS

更新日期：2017-09-01 00:00:00

abstract：:The gamma index is a tool that compares a dose distribution with a reference distribution by combining dose-difference and distance-to-agreement criteria. It has been widely used for ten years despite its high computational cost. This cost is due to both a search process for each reference point and the necessity to r...

journal_title：Medical physics

authors： Blanpain B,Mercier D

更新日期：2009-03-01 00:00:00

abstract：:In this x-ray/MR hybrid system an x-ray flat panel detector is placed under the patient cradle, close to the MR volume of interest (VOI), where the magnetic field strength is approximately 0.5 T. Immersed in this strong field, several electronic components inside the detector become magnetized and create an additional...

journal_title：Medical physics

authors： Wen Z,Fahrig R,Williams ST,Pelc NJ

更新日期：2008-09-01 00:00:00

abstract：:The concept of the radiological depth is central to all algorithms which calculate radiation dose in a heterogeneous medium. For a discrete heterogeneous medium, consisting of regions of inhomogeneity, the radiological depth is usually presented as the sum over segments of the product of the segment length and the inh...

journal_title：Medical physics

authors： Siddon RL

更新日期：1985-01-01 00:00:00

abstract：PURPOSE:Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be fu...

journal_title：Medical physics

authors： Teramoto A,Fujita H,Yamamuro O,Tamaki T

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:Transurethral MR-HIFU is a minimally invasive image-guided treatment for localized prostate cancer that enables precise targeting of tissue within the gland. The treatment is performed within a clinical MRI to obtain real-time MR thermometry used as an active feedback to control the spatial heating pattern in t...

journal_title：Medical physics

authors： Schmitt A,Mougenot C,Chopra R

更新日期：2014-11-01 00:00:00

abstract：:During the past decade the use of undersampled acquisition and constrained reconstruction have led to significant increases in data acquisition speed, SNR, spatial resolution and temporal resolution in MR imaging. When a separately acquired constraining image is combined with an angiographic time series the traditiona...

journal_title：Medical physics

authors： Mistretta C

更新日期：2012-06-01 00:00:00

abstract：:Modulation of the activity of the subthalamic nucleus (STN) using deep brain stimulation (DBS) in patients with advanced Parkinson's disease is the most common procedure performed today by functional neurosurgeons. The STN contours cannot be entirely identified on common 1.5 T images; in particular, the ventromedial b...

journal_title：Medical physics

authors： Stancanello J,Muacevic A,Sebastiano F,Modugno N,Cerveri P,Ferrigno G,Uggeri F,Romanelli P

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR (192)Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambe...

journal_title：Medical physics

authors： Araki F,Kouno T,Ohno T,Kakei K,Yoshiyama F,Kawamura S

更新日期：2013-09-01 00:00:00