Continuous time-dependence in computed tomography.

abstract：PURPOSE:The feasibility of intensity modulated brachytherapy (IMBT) to improve dose conformity for irregularly shaped targets has been previously investigated by researchers by means of using partially shielded sources. However, partial shielding does not fully explore the potential of IMBT. The goal of this study is t...

journal_title：Medical physics

authors： Shi C,Guo B,Cheng CY,Esquivel C,Eng T,Papanikolaou N

更新日期：2010-07-01 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:This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. METHODS:A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treat...

journal_title：Medical physics

authors： Pavoni JF,Pike TL,Snow J,DeWerd L,Baffa O

更新日期：2012-05-01 00:00:00

abstract：PURPOSE:The aim of this work was to provide a novel description of how the radiotherapy community configures treatment planning system (TPS) radiation beam models for clinically used treatment machines. Here we describe the results of a survey of self-reported TPS beam modeling parameter values across different C-arm l...

journal_title：Medical physics

authors： Glenn MC,Peterson CB,Followill DS,Howell RM,Pollard-Larkin JM,Kry SF

更新日期：2020-01-01 00:00:00

abstract：PURPOSE:Ultrasound-induced mild hyperthermia has advantages for noninvasive, localized and controlled drug delivery. In this study, a tissue-mimicking agarose-based phantom with a thermally sensitive indicator was developed for studying the spatial drug delivery profile using ultrasound-induced mild hyperthermia. METH...

journal_title：Medical physics

authors： Lai CY,Kruse D,Seo JW,Kheirolomoom A,Ferrara KW

更新日期：2013-08-01 00:00:00

abstract：:Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast impl...

journal_title：Medical physics

authors： Abboud F,Scalliet P,Vynckier S

更新日期：2008-12-01 00:00:00

abstract：PURPOSE:In the nuclear medicine department, the activity of radiopharmaceuticals is measured using dose calibrators (DCs) prior to patient injection. The DC consists of an ionization chamber that measures current generated by ionizing radiation (emitted from the radiotracer). In order to obtain an activity reading, the...

journal_title：Medical physics

authors： Esquinas PL,Tanguay J,Gonzalez M,Vuckovic M,Rodríguez-Rodríguez C,Häfeli UO,Celler A

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:This article presents an iterative method for compensation of motion artifacts for slowly rotating computed tomography (CT) systems. Patient's motion introduces inconsistencies among projections and yields severe reconstruction artifacts for free-breathing acquisitions. Streaks and doubling of structures can ap...

journal_title：Medical physics

authors： Schretter C,Rose G,Bertram M

更新日期：2009-11-01 00:00:00

abstract：:Seeds containing radioactive Ytterbium-169 (169Yb) have recently been manufactured for possible application to brachytherapy. Ytterbium-169 emits photons with an average energy of 93 keV (excluding energies less than 10 keV), and decays with a half-life of 32 days. Analytic and Monte Carlo computations have been used ...

journal_title：Medical physics

authors： Mason DL,Battista JJ,Barnett RB,Porter AT

更新日期：1992-05-01 00:00:00

abstract：PURPOSE:There is interest in developing linac-MR systems for MRI-guided radiation therapy. To date, the designs for such linac-MR devices have been restricted to a transverse geometry where the static magnetic field is oriented perpendicular to the direction of the incident photon beam. This work extends possibilities ...

journal_title：Medical physics

authors： Kirkby C,Murray B,Rathee S,Fallone BG

更新日期：2010-09-01 00:00:00

abstract：:An anthropomorphic 1H MRS head phantom has been developed which mimics the in vivo structure, metabolite concentrations, and relaxation times (for both water and metabolites) of human brain tissue. Different brain regions and two tumor types, fluid-containing ventricles, and air-filled sinus, and subcutaneous fat are ...

journal_title：Medical physics

authors： Rice JR,Milbrandt RH,Madsen EL,Frank GR,Boote EJ,Blechinger JC

更新日期：1998-07-01 00:00:00

abstract：PURPOSE:An optimized air ventilation system design for a treatment room in Heavy-ion Medical Facility is an important issue in the aspects of nuclear safety because the activated air produced in a treatment room can directly affect the medical staff and the general public in the radiation-free area. METHODS:Optimized ...

journal_title：Medical physics

authors： Kum O

更新日期：2018-06-01 00:00:00

abstract：PURPOSE:Patient-specific QA of highly conformal radiotherapy treatments are usually conducted using 2D or 3D dosimetry of the incident dose distribution in a water-equivalent phantom. However, dosimeters typically used for this task usually lack in either spatial resolution or dose accuracy. The purpose of this work is...

journal_title：Medical physics

authors： Goulet M,Archambault L,Beaulieu L,Gingras L

更新日期：2012-08-01 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：:Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S val...

journal_title：Medical physics

authors： Pacilio M,Lanconelli N,Lo MS,Betti M,Montani L,Torres AL,Coca PM

更新日期：2009-05-01 00:00:00

abstract：PURPOSE:For cone-beam computed tomography (CBCT) systems, we propose a sphere phantom based method to estimate the full three-dimensional (3D) modulation transfer function (MTF). METHODS:The FDK reconstruction of CBCT system in a local region was modeled by a triple convolution operator. Afterward, we calculated the d...

journal_title：Medical physics

authors： Lee C,Song HD,Baek J

更新日期：2020-07-01 00:00:00

abstract：:Three-dimensional water phantoms are routinely used when acquiring the data necessary to commission medical linear accelerators. A new water phantom controller has been developed at our institution that is unique in several aspects. The water phantom controller is based on an IBM XT compatible computer. This has been ...

journal_title：Medical physics

authors： Schmid MG,Morris RL

更新日期：1989-01-01 00:00:00

abstract：PURPOSE:Detailed characterization of changes in vessel size is crucial for the diagnosis and management of a variety of vascular diseases. Because clinical measurement of vessel size is typically dependent on the radiologist's subjective interpretation of the vessel borders, it is often prone to high inter- and intra-u...

journal_title：Medical physics

authors： O'Dell WG,Gormaley AK,Prida DA

更新日期：2017-12-01 00:00:00

abstract：PURPOSE:The management of thoracic malignancies with radiation therapy is complicated by continuous target motion. In this study, a real time motion analysis approach is proposed to improve the accuracy of patient setup. METHODS:For 11 lung cancer patients a long training fluoroscopy was acquired before the first trea...

journal_title：Medical physics

authors： Chen T,Jabbour SK,Qin S,Haffty BG,Yue N

更新日期：2013-04-01 00:00:00

abstract：PURPOSE:Quantification of body composition plays an important role in many clinical and research applications. Radiologic imaging techniques such as Dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and computed tomography (CT) imaging make accurate quantification of the body composition possibl...

journal_title：Medical physics

authors： Liu T,Udupa JK,Miao Q,Tong Y,Torigian DA

更新日期：2019-03-01 00:00:00

abstract：:Depth dose distributions for a d(14)Be neutron beam, measured separately for total and gamma absorbed dose, are presented for nine tissue substitutes and for two field sizes. These data are used to examine methods to transform depth dose curves from one material to another. Best results are found when the local depths...

journal_title：Medical physics

authors： Hensley FW,Rassow J,Temme A

更新日期：1985-05-01 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:A commonly used beam quality index (Q) for high-energy photon beams is the tissue phantom ratio (TPR20,10) for a square field of 10 x 10 cm2 and SDD of 100 cm. On some specialized radiotherapy treatment equipment such a reference collimator setting is not achievable. Likewise a flat beam profile, not explicitly...

journal_title：Medical physics

authors： Sauer OA

更新日期：2009-09-01 00:00:00

abstract：:The calibration (in rad/nC) of an air-filled tissue-equivalent ionization chamber for neutrons of 15-MeV average energy was determined by measuring absolute fluences and calculating the kerma per unit fluence. The neutron calibration determined from the gamma-ray calibration and application of the Bragg-Gray relation ...

journal_title：Medical physics

authors： Barschall HH,Goldberg E

更新日期：1977-03-01 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:Image guidance is crucial for percutaneous tumor ablations, enabling accurate needle-like applicator placement into target tumors while avoiding tissues that are sensitive to injury and/or correcting needle deflection. Although ultrasound (US) is widely used for image guidance, magnetic resonance (MR) is prefer...

journal_title：Medical physics

authors： Yamada A,Tokuda J,Naka S,Murakami K,Tani T,Morikawa S

更新日期：2020-03-01 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：:Consensus has been developing over the past few decades on a number of measurements required for the laboratory assessment of medical imaging modalities. Nevertheless, understanding of the connection between these measurements and human observer performance in a broad range of tasks remains far from complete. Focusing...

journal_title：Medical physics

authors： Metz CE,Wagner RF,Doi K,Brown DG,Nishikawa RM,Myers KJ

更新日期：1995-07-01 00:00:00

abstract：:The ability to control thermal drifts is essential in operating a calorimeter. We investigated a thermal enclosure, which envelops the calorimeter with temperature-regulated air, thus thermally isolating the calorimeter from the room. The desired temperature in the enclosure is controlled by a control circuit and a th...

journal_title：Medical physics

authors： Kubo H,Brown DE,Russell MD

更新日期：1985-05-01 00:00:00

abstract：PURPOSE:The recent development of multifocal stereotactic radiosurgery (SRS) using a single isocenter volumetric modulated arc theory (VMAT) technique warrants a re-examination of the quality assurance (QA) tolerances for routine mechanical QA recommended by the American Association of Physicists in Medicine Task Group...

journal_title：Medical physics

authors： Faught AM,Trager M,Yin FF,Kirkpatrick J,Adamson J

更新日期：2016-10-01 00:00:00