Abstract：
:The dose-calculation accuracy of the tomotherapy Hi-Art II(R) (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values < or =1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Chaudhari SR,Pechenaya OL,Goddu SM,Mutic S,Rangaraj D,Bradley JD,Low Ddoi
10.1088/0031-9155/54/8/004subject
Has Abstractpub_date
2009-04-21 00:00:00pages
2315-22issue
8eissn
0031-9155issn
1361-6560pii
S0031-9155(09)75309-6journal_volume
54pub_type
杂志文章abstract：:Range verification in proton therapy is a critical quality assurance task. We studied the feasibility of online range verification based on proton-induced acoustic signals, using a bidirectional long-short-term-memory recurrent neural network and various signal processing techniques. Dose distribution of 1D pencil pro...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/abaa5e
更新日期：2020-11-05 00:00:00
abstract：:Intra-fractional motion is a concern during prostate radiation therapy, as it may cause deviations between planned and delivered radiation doses. Because accurate motion information during treatment delivery is critical to address dose deviation, we developed the projection marker matching method (PM3), a novel method...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa6e37
更新日期：2017-07-07 00:00:00
abstract：:The purpose of this paper for four-dimensional (4D) computed tomography (CT) is threefold. (1) A new spatiotemporal model is presented from the matrix perspective with the row dimension in space and the column dimension in time, namely the robust PCA (principal component analysis)-based 4D CT model. That is, instead o...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/11/002
更新日期：2011-06-07 00:00:00
abstract：:This study evaluates the dosimetric performance of the polymer gel dosimeter 'Methacrylic and Ascorbic acid in Gelatin, initiated by Copper' and its suitability for quality assurance and analysis of I-131-targeted radionuclide therapy dosimetry. Four batches of gel were manufactured in-house and sets of calibration vi...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/22/017
更新日期：2011-11-21 00:00:00
abstract：:Online adaptive radiation therapy (ART) based on real-time magnetic resonance imaging represents a paradigm-changing treatment scheme. However, conventional quality assurance (QA) methods based on phantom measurements are not feasible with the patient on the treatment couch. The purpose of this work is to develop a fa...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa6e38
更新日期：2017-06-21 00:00:00
abstract：:The energy dependence of alanine/EPR dosimetry, in terms of absorbed dose-to-water for clinical 6, 10, 25 MV x-rays and 60Co gamma-rays was investigated by measurements and Monte Carlo (MC) calculations. The dose rates were traceable to the NRC primary standard for absorbed dose, a sealed water calorimetry. The electr...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/49/2/006
更新日期：2004-01-21 00:00:00
abstract：:For angiography using synchrotron radiation we measured the absorbed dose distribution in inhomogeneous phantoms with thin LiF:Mg, Cu, P, LiF:Mg, Ti thermoluminescent dosimeters (TLDs) in tissue and lung substitutes, and with Mg2SiO4:Tb TLDs in bone substitute for 33.32 keV monoenergetic photons from synchrotron radia...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/46/3/308
更新日期：2001-03-01 00:00:00
abstract：:This study looks at blood flow in four different human right coronary arteries (RCAs), which have been reconstructed from bi-plane angiograms. A generalized power-law model of blood viscosity is used to study the blood flow at a particular point in the cardiac cycle. Large differences are found in the wall shear stres...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/9/013
更新日期：2007-05-07 00:00:00
abstract：:This paper reports an inverse arc-modulated radiation therapy planning technique based on linear models. It is implemented with a two-step procedure. First, fluence maps for 36 fixed-gantry beams are generated using a linear model-based intensity-modulated radiation therapy (IMRT) optimization algorithm. The 2D fluenc...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/55/13/020
更新日期：2010-07-07 00:00:00
abstract：:A hydrogen clearance technique for the measurement of capillary blood flow in skeletal muscle (both resting and working) and the beating heart in experimental animals is described. Various methods for introducing the hydrogen into the region of measurement are compared, together with the appropriate methods for evalua...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/34/10/005
更新日期：1989-10-01 00:00:00
abstract：:Beta emitting 106Ru-applicators are used to treat choroidal melanoma. In order to improve the accuracy and simplify the dosimetry of these applicators, the suitability of using a p-type silicon semiconductor detector has been investigated. The detector is calibrated in a low energy electron beam. An important property...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/36/7/005
更新日期：1991-07-01 00:00:00
abstract：:A single photon absorptiometry method to measure the arterial concentration of injected iodinated contrast agent was developed. A prototype absorptiometry unit was built which consists of either a square or circular cross section acrylic (polymethylmethacrylate) cuvette connected to an arterial catheter at one end and...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/37/9/002
更新日期：1992-09-01 00:00:00
abstract：:Measurements of patient entrance surface dose rate provide valuable data for interpreting results from dose-area product studies on fluoroscopic x-ray equipment. Methods for measurement of entrance surface dose rate with backscatter and incident dose rate without backscatter have been investigated. Entrance surface do...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/40/5/008
更新日期：1995-05-01 00:00:00
abstract：:The clinical value of multiple b-value diffusion-weighted (DW) magnetic resonance imaging (MRI) has been shown in many studies. However, DW-MRI often suffers from low signal-to-noise ratio, especially at high b-values. To address this limitation, we present an image denoising method based on the concept of deep image ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab8105
更新日期：2020-05-11 00:00:00
abstract：:The analysis of (x-ray) mammograms remains qualitative, relying on the judgement of clinicians. We present a novel method to compute a quantitative, normalized measure of tissue radiodensity traversed by the primary beam incident on each pixel of a mammogram, a measure we term the standard attenuation rate (SAR). SAR ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/57/20/6519
更新日期：2012-10-21 00:00:00
abstract：:A radiofrequency and field-gradient pulse sequence is presented permitting the non-invasive, volume-selective and spectroscopically resolved determination of incoherent transport parameters with the aid of an NMR field-gradient method. With proton NMR, diffusion or (quasi-incoherent) perfusion coefficients as low as 1...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/35/1/007
更新日期：1990-01-01 00:00:00
abstract：:Determining plaque vulnerability is critical when selecting the most suitable treatment for patients with atherosclerotic plaque. Currently, clinical non-invasive ultrasound-based methods for plaque characterization are limited to visual assessment of plaque morphology and new quantitative methods are needed. In this ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/60/8/3151
更新日期：2015-04-21 00:00:00
abstract：:The absolute dose rate around beta sources for intravascular brachytherapy was measured with thin thermoluminescent (TL) dosimeters and radiochromic film. The calibration of these dosimeters was performed at the dose maximum in a 6 MeV electron beam of a linear accelerator. Compared to the values given by the manufact...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/45/8/311
更新日期：2000-08-01 00:00:00
abstract：:Dose calculation for radiotherapy with protons and heavier ions deals with a large volume of path integrals involving a scattering power of body tissue. This work provides a simple model for such demanding applications. There is an approximate linearity between RMS end-point displacement and range of incident particle...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/5/N01
更新日期：2009-03-07 00:00:00
abstract：:A theoretical analysis and numerical solutions are presented for viscosity-dominated flow through a uniform, highly distensible tube with a slit-shaped cross section undergoing peristalsis. At flow rates below an intrinsic upper limit to the peristaltic carrying capacity of the tube, provided that there is always at l...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/32/7/002
更新日期：1987-07-01 00:00:00
abstract：:In a previous paper the calibration of an isotropic light detector in clear media was described and validated. However, in most applications the detector is used to measure light distribution in turbid (scattering) media, that is, in tissues or tissue equivalent optical phantoms. Despite its small diameter (typically ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/47/12/304
更新日期：2002-06-21 00:00:00
abstract：:Elastography, which uses ultrasound to image the tissue strain that results from an applied displacement, can display tumours and heat-ablated tissue with high contrast. However, its application to liver in vivo may be problematic due to the presence of respiratory and cardiovascular sources of displacement. The aim o...
journal_title：Physics in medicine and biology
pub_type： 临床试验,杂志文章
doi：10.1088/0031-9155/49/18/001
更新日期：2004-09-21 00:00:00
abstract：:An original method for the analysis of oscillations of cutaneous blood flow has been developed, which makes use of laser Doppler flowmetry (LDF) data and is based on the continuous wavelet transform and adaptive wavelet theory. The potential of the method has been demonstrated in experiments with the response of micro...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/53/21/005
更新日期：2008-11-07 00:00:00
abstract：:This paper presents a computerized method for the selection of an irregular region of interest (ROI) in broadband ultrasound attenuation (BUA) images. A region growing algorithm searches an initial region in the posterior part of the calcaneus until the pixel with the lowest attenuation value is found; this is the sta...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/47/2/310
更新日期：2002-01-21 00:00:00
abstract：:Abdominal organ motion may lead to considerable uncertainties in pencil-beam scanning (PBS) proton therapy of pancreatic cancer. Beam gating, where irradiation only occurs in certain breathing phases in which the gating conditions are fulfilled, may be an option to reduce the interplay effect between tumor motion and ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab1175
更新日期：2019-04-10 00:00:00
abstract：:For conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align the radiation and imaging isocenter may require a modifica...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aac228
更新日期：2018-05-29 00:00:00
abstract：:Computational phantoms are commonly used in internal radiation dosimetry to assess the amount and distribution pattern of energy deposited in various parts of the human body from different internal radiation sources. Radiation dose assessments are commonly performed on predetermined reference computational phantoms wh...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa75b4
更新日期：2017-07-13 00:00:00
abstract：:Four-dimensional (4D) methods strive to achieve highly conformal radiotherapy, particularly for lung and breast tumours, in the presence of respiratory-induced motion of tumours and normal tissues. Four-dimensional radiotherapy accounts for respiratory motion during imaging, planning and radiation delivery, and requir...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/48/1/304
更新日期：2003-01-07 00:00:00
abstract：:Assessment of image quality for digital x-ray mammography systems used in European screening programs relies mainly on contrast-detail CDMAM phantom scoring and requires the acquisition and analysis of many images in order to reduce variability in threshold detectability. Part II of this study proposes an alternative ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/14/003
更新日期：2011-07-21 00:00:00
abstract：:An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) fo...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/58/13/4643
更新日期：2013-07-07 00:00:00
