A feasible method for clinical delivery verification and dose reconstruction in tomotherapy.

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

abstract：:Gd2O2S phosphor screens between 250 and 1000 mg/cm2 thick were evaluated for use in megavoltage imaging systems. The phosphor layers were placed on brass plates ranging from 1 to 5 mm thick, each with and without an optical back reflector (white paint). Light output and spatial resolution were measured at 6- and 23-MV...

journal_title：Medical physics

authors： Wowk B,Shalev S

更新日期：1994-08-01 00:00:00

abstract：:A very important issue in contemporary inverse treatment radiotherapy planning is the specification of proper dose-volume constraints limiting the treatment planning algorithm from delivering high doses to the normal tissue surrounding the tumor. Recently we have proposed a method called reverse mapping of normal tiss...

journal_title：Medical physics

authors： Markov K,Schinkel C,Stavreva N,Stavrev P,Weldon M,Fallone BG

更新日期：2006-09-01 00:00:00

abstract：:Single kernel scatter correction algorithms are based on the model that the scatter field can be predicted by convolution of the primary intensity (Iprim) with a spatially invariant scatter point-spread function (PSF). Practical limitations (Iprim unknown) suggest the substitution of the total detected intensity (Idet...

journal_title：Medical physics

authors： Kruger DG,Zink F,Peppler WW,Ergun DL,Mistretta CA

更新日期：1994-02-01 00:00:00

abstract：PURPOSE:In order to build up a reliable dose monitoring system for boron neutron capture therapy (BNCT) applications at the TRIGA reactor in Mainz, a computer model for the entire reactor was established, simulating the radiation field by means of the Monte Carlo method. The impact of different source definition techni...

journal_title：Medical physics

authors： Ziegner M,Schmitz T,Khan R,Blaickner M,Palmans H,Sharpe P,Hampel G,Böck H

更新日期：2014-11-01 00:00:00

abstract：PURPOSE:We investigated the feasibility of using simpler methods than manual whole-organ volume-of-interest (VOI) definition to estimate the organ activity concentration in single photon emission computed tomography (SPECT) in cases where the activity in the organ can be assumed to be uniformly distributed on the scale...

journal_title：Medical physics

authors： Vicente EM,Lodge MA,Rowe SP,Wahl RL,Frey EC

更新日期：2017-05-01 00:00:00

abstract：:Subsecond single-slice, multi-slice or cone-beam spiral computed tomography (SSCT, MSCT, CBCT) offer great potential for improving heart imaging. Together with the newly developed phase-correlated cardiac reconstruction algorithms 180 degrees MCD and 180 degrees MCI [Med. Phys. 27, 1881-1902 (2000)] or related algorit...

journal_title：Medical physics

authors： Kachelriess M,Sennst DA,Maxlmoser W,Kalender WA

更新日期：2002-07-01 00:00:00

abstract：PURPOSE:The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different...

journal_title：Medical physics

authors： Schmitz T,Bassler N,Blaickner M,Ziegner M,Hsiao MC,Liu YH,Koivunoro H,Auterinen I,Serén T,Kotiluoto P,Palmans H,Sharpe P,Langguth P,Hampel G

更新日期：2015-01-01 00:00:00

abstract：:Spread of invasive carcinoma throughout breast tissue is believed to occur at supramolecular levels, beyond the range of standard histopathology identification. Small angle x-ray scattering (SAXS) is capable of characterizing the structural properties of collagen and tissue found in the breast at the scale of tens to ...

journal_title：Medical physics

authors： Sidhu S,Siu KK,Falzon G,Hart SA,Foxe JG,Lewis RA

更新日期：2009-07-01 00:00:00

abstract：:Ionization chambers of varying inside diameter have been used to investigate the penumbral region of 60Co, 6-MV, and 31-MV x-ray beams. Measurements were made in water at varying depths up to 25 cm for a square field of side length 10 cm. The dependence of the penumbral widths on both the inside diameter of the ioniza...

journal_title：Medical physics

authors： Dawson DJ,Schroeder NJ,Hoya JD

更新日期：1986-01-01 00:00:00

abstract：:The aim of this study is to perform a statistical analysis to verify the calculated percentage depth dose (PDD) based on the tissue maximum ratio (TMR) with the PDD measurements taken in water. 6 and 15 MV photon beams produced by a Varian linear 2100 C/D accelerator were used. PDDs and TMRs were measured at various d...

journal_title：Medical physics

authors： Isa M,Iqbal K,Afzal M,Buzdar S,Chow J

更新日期：2012-07-01 00:00:00

abstract：:Numerical reconstruction of x-ray spectra from narrow-beam transmission data was tested with published spectra in the range from 45 to 100 kVp. Transmission curves were calculated from the spectra to simulate measured data. Spectra were reconstructed from these transmission curves with use of an iterative numerical an...

journal_title：Medical physics

authors： Huang PH,Chen TS,Kase KR

更新日期：1986-09-01 00:00:00

abstract：PURPOSE:Distortions in magnetic resonance imaging (MRI) compromise spatial fidelity, potentially impacting delineation and dose calculation. We characterized 2D and 3D large field of view (FOV), sequence-independent distortion at various positions in a 1.0 T high-field open MR simulator (MR-SIM) to implement correction...

journal_title：Medical physics

authors： Price RG,Kadbi M,Kim J,Balter J,Chetty IJ,Glide-Hurst CK

更新日期：2015-10-01 00:00:00

abstract：:Calcium concentration may be a useful feature for distinguishing benign from malignant lung nodules in computer-aided diagnosis. The calcium concentration can be estimated from the measured CT number of the nodule and a CT number vs calcium concentration calibration line that is derived from CT scans of two or more ca...

journal_title：Medical physics

authors： Goodsitt MM,Chan HP,Way TW,Schipper MJ,Larson SC,Christodoulou EG

更新日期：2009-07-01 00:00:00

abstract：:The anti-scatter grid has been widely used to reject scatter and increase the perceptibility of a low-contrast object in chest radiography; however, it also attenuated the primary x-rays, resulting in a substantial loss of information and an increased relative noise level in heavily attenuated regions. A more dose eff...

journal_title：Medical physics

authors： Liu X,Shaw CC

更新日期：2007-07-01 00:00:00

abstract：:A PTW Riga diamond detector and LiF TLDs have been evaluated for use in proton beam dosimetry by comparing results of proton beam calibration with those obtained using thimble ionization chambers. The thimble ionization chambers were calibrated in terms of exposure while the TLDs and diamond detector were calibrated i...

journal_title：Medical physics

authors： Vatnitsky S,Miller D,Siebers J,Moyers M

更新日期：1995-04-01 00:00:00

abstract：PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...

journal_title：Medical physics

authors： Fast MF,Wisotzky E,Oelfke U,Nill S

更新日期：2013-09-01 00:00:00

abstract：:The purpose of this study is to perform a clinical evaluation of the first commercial (MDS Nordion, now Nucletron) treatment planning system for electron beams incorporating Monte Carlo dose calculation module. This software implements Kawrakow's VMC++ voxel-based Monte Carlo calculation algorithm. The accuracy of the...

journal_title：Medical physics

authors： Cygler JE,Daskalov GM,Chan GH,Ding GX

更新日期：2004-01-01 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：: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:To use EGSnrc Monte Carlo simulations for magnetic field dosimetry to determine optimal measurement orientations, calculate beam quality conversion factors for 32 cylindrical and three parallel-plate (PP) ion chambers, evaluate the beam quality and angular dependence of these factors, and examine the magnetic f...

journal_title：Medical physics

authors： Malkov VN,Rogers DWO

更新日期：2018-02-01 00:00:00

abstract：:Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programm...

journal_title：Medical physics

authors： Yang S,Wang G,Skinner MW,Rubinstein JT,Vannier MW

更新日期：2000-04-01 00:00:00

abstract：PURPOSE:Identification of calcifications and hemorrhages is essential for the etiological diagnosis of cerebral lesions. The purpose of this work was to develop a robust method for characterization of para- and diamagnetic intracerebral lesions based on clinical gradient-echo magnetic resonance phase data acquired at 1...

journal_title：Medical physics

authors： Schweser F,Deistung A,Lehr BW,Reichenbach JR

更新日期：2010-10-01 00:00:00

abstract：PURPOSE:The depth dose of a monoenergetic broad parallel proton beam has been modeled in a number of ways, but evidently not yet for oblique incidence. The purpose of this investigation is to find an accurate analytic formula for this case, which can then be used to model the depth dose of a broad beam with an initial ...

journal_title：Medical physics

authors： Jette D,Yuan J,Chen W

更新日期：2010-11-01 00:00:00

abstract：:Effectiveness of an oral presentation depends on the ability of the speaker to communicate with the audience. An important part of this communication is focusing on two to five key points and emphasizing those points during the presentation. Every aspect of the presentation should be purposeful and directed at facilit...

journal_title：Medical physics

authors： Collins J,Aydogan B

更新日期：2012-06-01 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：: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

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:The implementation of an accurate beam model is an integral part of the commissioning of any planning system. This process is especially challenging in the case of IMRT beam models owing to the complexity of small field sizes and MLC leaf-end and tongue-and-groove effects. The question of how to judge the quali...

journal_title：Medical physics

authors： Veltchev I,Fourkal E,Price R,Ma C

更新日期：2012-06-01 00:00:00

abstract：:Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (...

journal_title：Medical physics

authors： Raylman RR,Majewski S,Wojcik R,Weisenberger AG,Kross B,Popov V,Bishop HA

更新日期：2000-08-01 00:00:00