Performance characteristics of transmission imaging using a uniform sheet source with parallel-hole collimation.

abstract：PURPOSE:In this study, the authors validated a novel respiratory tracking device, the multidimensional respiratory tracking (MDRT) system, that was designed to assist in correcting for respiratory motion in PET/CT images. The authors also investigated a novel PET acquisition technique, smart gating (SG), that enables t...

journal_title：Medical physics

authors： Nehmeh SA,Haj-Ali AA,Qing C,Stearns C,Kalaigian H,Kohlmyer S,Schoder H,Ho AY,Larson SM,Humm JL

更新日期：2011-01-01 00:00:00

abstract：PURPOSE:Four-dimensional volumetric modulated arc therapy (4D VMAT) and four-dimensional intensity-modulated radiotherapy (4D IMRT) are developing radiation therapy treatment strategies designed to maximize dose conformality, minimize normal tissue dose, and deliver the treatment as efficiently as possible. The patient...

journal_title：Medical physics

authors： Klawikowski S,Tai A,Ates O,Ahunbay E,Li XA

更新日期：2018-04-01 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:To investigate whether building a knowledge-based planning (KBP) model with prostate bed plans constructed from constrained hierarchical optimization (CHO) would result in more efficient model construction with more consistent output than a model built using plans from a traditional, trial-and-error-based optim...

journal_title：Medical physics

authors： Lin YH,Hong LX,Hunt MA,Berry SL

更新日期：2018-10-01 00:00:00

abstract：:To account for clinical divergent and polychromatic photon beams, we have developed kernel tilting and kernel hardening correction methods for convolution dose calculation algorithms. The new correction methods were validated by Monte Carlo simulation. The accuracy and computation time of the our kernel tilting and ke...

journal_title：Medical physics

authors： Liu HH,Mackie TR,McCullough EC

更新日期：1997-11-01 00:00:00

abstract：PURPOSE:Tumor motion during radiotherapy can cause a reduction in target dose coverage and an increase in healthy tissue exposure. Tumor motion is not strictly translational and often exhibits complex six degree-of-freedom (6DoF) translational and rotational motion. Although the dosimetric impact of prostate tumor tran...

journal_title：Medical physics

authors： Shi K,Dipuglia A,Booth J,Alnaghy S,Kyme A,Keall P,Nguyen DT

更新日期：2020-12-01 00:00:00

abstract：PURPOSE:X-ray fluorescence computer tomography (XFCT) is a new molecular imaging modality which uses x-ray excitation to stimulate the emission of fluorescent photons in high atomic number contrast agents. Scatter contamination is one of the main challenges in XFCT imaging which limits the molecular sensitivity. When p...

journal_title：Medical physics

authors： Vernekohl D,Tzoumas S,Zhao W,Xing L

更新日期：2018-05-25 00:00:00

abstract：:Dose calculations for treatment planning of photon beam radiotherapy require a model of the beam to drive the dose calculation models. The beam shaping process involves scattering and filtering that yield radiation components which vary with collimator settings. The necessity to model these components has motivated th...

journal_title：Medical physics

authors： Ahnesjö A,Weber L,Murman A,Saxner M,Thorslund I,Traneus E

更新日期：2005-06-01 00:00:00

abstract：:In this work, we present a calcification-detection scheme that automatically localizes calcifications in a previously detected cluster in order to generate the input for a cluster-classification scheme developed in the past. The calcification-detection scheme makes use of three pieces of a priori information: the loca...

journal_title：Medical physics

authors： Salfity MF,Nishikawa RM,Jiang Y,Papaioannou J

更新日期：2003-05-01 00:00:00

abstract：PURPOSE:To investigate energy deposition in glandular tissues of the breast on macro- and microscopic length scales in the context of mammography. METHODS:Multiscale mammography models of breasts are developed, which include segmented, voxelized macroscopic tissue structure as well as nine regions of interest (ROIs) e...

journal_title：Medical physics

authors： Oliver PAK,Thomson RM

更新日期：2019-03-01 00:00:00

abstract：:A computerized scheme is being developed for the detection of masses in digital mammograms. Based on the deviation from the normal architectural symmetry of the right and left breasts, a bilateral subtraction technique is used to enhance the conspicuity of possible masses. The scheme employs two pairs of conventional ...

journal_title：Medical physics

authors： Yin FF,Giger ML,Doi K,Metz CE,Vyborny CJ,Schmidt RA

更新日期：1991-09-01 00:00:00

abstract：:Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmet...

journal_title：Medical physics

authors： Shepard DM,Olivera G,Angelos L,Sauer O,Reckwerdt P,Mackie TR

更新日期：1999-07-01 00:00:00

abstract：PURPOSE:The accuracy and precision of computed tomography (CT) pulmonary ventilation imaging with conventional CT scanners are limited by breathing variations. We propose a method to correct for the effect of breathing variations in CT ventilation imaging based on external respiratory signals acquired throughout a scan...

journal_title：Medical physics

authors： Yamamoto T,Kabus S

更新日期：2018-01-01 00:00:00

abstract：PURPOSE:Transcranial focused ultrasound is an emerging therapeutic modality that can be used to perform noninvasive neurosurgical procedures. The current clinical transcranial phased array operates at 650 kHz, however the development of a higher frequency array would enable more precision, while reducing the risk of st...

journal_title：Medical physics

authors： Pajek D,Hynynen K

更新日期：2013-12-01 00:00:00

abstract：:The computational aspects of the design of an optical distance indicator (ODI) for use with a radiation therapy accelerator are discussed. The specifics of the optical and mechanical design of an ODI for use with a superconducting cyclotron used for fast neutron therapy are presented. ...

journal_title：Medical physics

authors： Maughan RL

更新日期：1999-02-01 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:Atherosclerosis of peripheral cerebral arteries can lead to stroke either by stenosis formation or plaque rupture. This pathology is initiated by the alteration of arterial wall mechanical properties shown to be assessable by ultrasound elastography. Recently, noninvasive vascular elastography (NIVE) was introd...

journal_title：Medical physics

authors： Mercure E,Deprez JF,Fromageau J,Basset O,Soulez G,Cloutier G,Maurice RL

更新日期：2011-02-01 00:00:00

abstract：PURPOSE:High-quality radiation therapy using highly conformal dose distributions and image-guided techniques requires optimum machine delivery performance. In this work, a monitoring system for multileaf collimator (MLC) performance, integrating semiautomated MLC quality control (QC) tests and statistical process contr...

journal_title：Medical physics

authors： Létourneau D,Wang A,Amin MN,Pearce J,McNiven A,Keller H,Norrlinger B,Jaffray DA

更新日期：2014-12-01 00:00:00

abstract：:A new approach to the calculation of the x-ray spectrum emerging from an x-ray tube is proposed. Theoretical results for the bremsstrahlung cross section appearing in the literature are summarized. Four different treatments of electron penetration, based on the work presented in Part I, are then used to generate brems...

journal_title：Medical physics

authors： Poludniowski GG

更新日期：2007-06-01 00:00:00

abstract：:The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x ...

journal_title：Medical physics

authors： Grein EE,Lee R,Luchka K

更新日期：2002-10-01 00:00:00

abstract：PURPOSE:To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. METHODS:Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multip...

journal_title：Medical physics

authors： Audet C,Poffenbarger BA,Chang P,Jackson PS,Lundahl RE,Ryu SI,Ray GR

更新日期：2011-11-01 00:00:00

abstract：PURPOSE:MR-guided radiation therapy (RT) offers unparalleled soft tissue contrast for localization and target tracking. However, MRI distortions may be detrimental to high precision RT. This work characterizes the gradient nonlinearity (GNL) and total distortions over the first year of clinical operation of a 0.35T MR-...

journal_title：Medical physics

authors： Nejad-Davarani SP,Kim JP,Du D,Glide-Hurst C

更新日期：2019-05-01 00:00:00

abstract：PURPOSE:The purpose of this study was to assess, using an anthropomorphic digital phantom, the accuracy of algorithms in registering precontrast and contrast-enhanced computed tomography (CT) chest images for generation of iodine maps of the pulmonary parenchyma via temporal subtraction. MATERIALS AND METHODS:The XCAT...

journal_title：Medical physics

authors： Grob D,Oostveen L,Rühaak J,Heldmann S,Mohr B,Michielsen K,Dorn S,Prokop M,Kachelrieβ M,Brink M,Sechopoulos I

更新日期：2019-05-01 00:00:00

abstract：:Proton NMR spectroscopy was applied to quantitate the measurement of total body water/fat distributions in vivo. A special MR protocol was developed to excite a thick slab of tissue and display the magnitude NMR spectrum of the collected response signal. Very short echo time TE (8 ms) and long repetition time TR (4000...

journal_title：Medical physics

authors： Sobol WT,Elster AD,Hinson WH,Chwals WJ

更新日期：1992-01-01 00:00:00

abstract：:Interchange or transfer of radiographic techniques through measurement of penetration quality is discussed. The usefulness of this achievement is verified using an aluminum step wedge. Also, the procedure described provides a method for performance evaluation of kVp compensation on diagnostic x-ray installations. ...

journal_title：Medical physics

authors： Lin PJ

更新日期：1975-01-01 00:00:00

abstract：:Variation of the photoactivation rate across radiation fields of three different bremsstrahlung beams of two medical accelerators has been measured, making use of the photonuclear reactions in natural indium probes: 115In(y,y')115mIn and 115In(y,n)114mIn. The third nuclear reaction, 115In(n,y)116mIn, was used to detec...

journal_title：Medical physics

authors： Krmar M,Slivka J,Bikit I,Conkić L,Rudić A

更新日期：1999-04-01 00:00:00

abstract：PURPOSE:A dynamic bowtie filter can modulate flux along both fan and view angles for reduced patient dose, scatter, and required photon flux, which is especially important for photon counting detectors (PCDs). Among the proposed dynamic bowtie designs, the piecewise-linear attenuator (Hsieh and Pelc, Med Phys. 2013;40:...

journal_title：Medical physics

authors： Shunhavanich P,Hsieh SS,Pelc NJ

更新日期：2019-01-01 00:00:00

abstract：PURPOSE:The image registration literature comprises many methods for 2D-3D registration for which accuracy has been established in a variety of applications. However, clinical application is limited by a small capture range. Initial offsets outside the capture range of a registration method will not converge to a succe...

journal_title：Medical physics

authors： van der Bom MJ,Bartels LW,Gounis MJ,Homan R,Timmer J,Viergever MA,Pluim JP

更新日期：2010-04-01 00:00:00

abstract：:Neutron and photon energy spectra were measured in different depths and lateral positions in tissue-equivalent phantoms exposed to a therapeutical 14.1 MeV neutron beam. Intensity weighted mass energy absorption coefficients were derived for application in ionization chamber dosimetry in mixed neutron-gamma fields. Th...

journal_title：Medical physics

authors： Schmidt R,Magiera E,Scobel W

更新日期：1980-09-01 00:00:00

abstract：:We investigated protection strategies of organs at risk (OARs) in intensity modulated radiation therapy (IMRT). These strategies apply to delivery of IMRT to moving body anatomies that show relative displacement of OAR in close proximity to a tumor target. We formulated an efficient genetic algorithm which makes it po...

journal_title：Medical physics

authors： Abolfath RM,Papiez L

更新日期：2009-07-01 00:00:00