Abstract：
:A computed tomography (CT) based system that compensates for patient surface contour and internal tissue inhomogeneity was implemented in our clinic. The compensators are fabricated with a mixture of tin granules and bee's wax. The tin/wax mixture was optimized for tin granule size and tin granule to wax ratio. The narrow beam attenuation coefficients were measured for 4-, 6-, 10-, and 24-MV photon beams. The compensator design and fabrication methodology were verified by measuring the dose distribution for a known surface contour irradiated with a compensated beam and for a known inhomogeneity that was submerged in a water phantom and irradiated with a compensated beam. For the surface contour, the uncompensated isodose levels varied by as much as 10% in the compensation plane and the compensator restored the isodose level to a variation of less than 1.3%. Measured and calculated doses for this surface contour were found to differ by less than 3.4%. For the inhomogeneity, the uncompensated isodose levels varied by 27% in the compensation plane and the compensator restored the isodose level to a variation of less than 1.5%. Measured and calculated doses for the known inhomogeneity were found to differ by less than 2%. Measurements of depth-dose curves indicate that the presence of the compensator in the beam does not significantly increase the surface dose. Twenty-six compensators have now been fabricated for clinical cases. In these patients, dose variations as great as 19% occurred in the plane of compensation prior to placing the compensator in the beam.(ABSTRACT TRUNCATED AT 250 WORDS)
journal_name
Med Physjournal_title
Medical physicsauthors
Jursinic PA,Podgorsak MB,Paliwal BRdoi
10.1118/1.597303subject
Has Abstractpub_date
1994-03-01 00:00:00pages
357-65issue
3eissn
0094-2405issn
2473-4209journal_volume
21pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:In the present investigation, the necessary tests for implementing a quality assurance program for a commercial treatment planning system (TPS), recently installed at Sao Paulo University School of Medicine Clinicas Hospital-Brazil, was established and performed in accordance with the new IAEA publication TRS 430, and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2742779
更新日期：2007-07-01 00:00:00
abstract：:The objective of this work is to assess the suitability and performance of a new dosimeter system with a novel geometry for the quality assurance (QA) of volumetric modulated arc therapy (VMAT). The new dosimeter system consists of a hollow cylinder (15 and 25 cm inner and outer diameters) with 124 diodes embedded in ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3117563
更新日期：2009-05-01 00:00:00
abstract：:Intensity modulated radiation therapy (IMRT) with a dynamic multileaf collimator (DMLC) requires synchronization of DMLC leaf motion with dose delivery. A delay in DMLC communication is known to cause leaf lag and lead to dosimetric errors. The errors may be exacerbated by gated operation. The purpose of this study wa...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1592017
更新日期：2003-08-01 00:00:00
abstract：PURPOSE:To use machine-learning algorithms and blur measure (BM) operators to automatically detect motion blur in mammograms. Motion blur has been reported to reduce lesion detection performance and mask small abnormalities, resulting in failure to detect them until they reach more advanced stages. Automatic detection ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14069
更新日期：2020-04-01 00:00:00
abstract：PURPOSE:Automatic breast ultrasound (ABUS) imaging has become an essential tool in breast cancer diagnosis since it provides complementary information to other imaging modalities. Lesion segmentation on ABUS is a prerequisite step of breast cancer computer-aided diagnosis (CAD). This work aims to develop a deep learnin...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14569
更新日期：2020-10-30 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
pub_type： 杂志文章
doi：10.1118/1.4704496
更新日期：2012-05-01 00:00:00
abstract：:A commercial optical system developed by Solid Photography, Inc., has been used to generate precise paraffin--polyethylene tissue compensators. A program with the objective of constructing a medical facility has been undertaken to access patient topology for treatment planning, tissue-compensator fabrication, and pati...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594447
更新日期：1978-11-01 00:00:00
abstract：:Nuclear Magnetic Resonance (NMR) permits the noninvasive measurement of blood flow signals unimpaired by clothes, bandages, casts, etc. The cylindrical crossed-coil NMR blood flowmeter was used to measure blood flow through a cross-section of the human forearm. Two calibration procedures are described: one for pulsati...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594989
更新日期：1981-07-01 00:00:00
abstract：PURPOSE:To present EBT2 film verification of treatment planning with the eXtend System, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery. METHODS:A human head shaped phantom simulated the verification process for fractionated Gamma Knife (GK) treatment. Phantom preparation for e...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735487
更新日期：2012-06-01 00:00:00
abstract：:For the case of eye tumor therapy with protons, improvements are introduced compared to the standard dose calculation which implies straight-line optics and the constant-density assumption for the eye and its surrounding. The progress consists of (i) taking account of the lateral scattering of the protons in tissue by...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2168067
更新日期：2006-03-01 00:00:00
abstract：PURPOSE:A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not. METHODS:In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validate...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3187231
更新日期：2009-09-01 00:00:00
abstract：PURPOSE:Radiation therapy is often delivered by multiple sequential treatment plans. For an accurate radiobiological evaluation of the overall treatment, fractionation corrections to each dose distribution must be applied before summing the three-dimensional dose matrix of each plan since the simpler approach of perfor...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4792636
更新日期：2013-03-01 00:00:00
abstract：:An algorithmic solution to the biological effective dose (BED) calculation from the Lea-Catcheside formula for a piecewise defined function is presented. Data from patients treated for metastatic thyroid cancer were used to illustrate the solution. The Lea-Catcheside formula for the G-factor of the BED is integrated n...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3070587
更新日期：2009-03-01 00:00:00
abstract：PURPOSE:The purpose of this study was to characterize the Hounsfield unit (HU) distributions of mesothelioma and other tissues present in contrast-enhanced thoracic CT scans, to compare the HU distributions of mesothelioma, muscle, and liver by scanner and reconstruction filter/kernel combination, and to assess interpa...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3537610
更新日期：2011-02-01 00:00:00
abstract：PURPOSE:Quantitative SPECT imaging is limited by many factors, including penetration of high energy photons through the collimator. Even small peaks of high energy yield extensive contamination in the photopeak energy window. Rotating slat collimators typically offer a 40- to 50-fold increase in geometric detection eff...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3177312
更新日期：2009-09-01 00:00:00
abstract：PURPOSE:To study if malfunction of a receiver can be detected robustly using the simple ACR SNR measurement approach on a 32-channel head coil. METHODS:Standard ACR T1W images (11slice) were acquired with a commercial 32 channel head coil on a 3T Philips Achieva MR scanner following the ACR recommended setup. Raw data...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736227
更新日期：2012-06-01 00:00:00
abstract：:Carlo Fidani Peel Regional Cancer Center at the Credit Valley Site of the Credit Valley Hospital and Trillium Health Center is currently undergoing a redevelopment to build a brachytherapy suite and associated areas with a projected start date of April 2013. The new brachytherapy suite will be located in the PRCC, and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4740117
更新日期：2012-07-01 00:00:00
abstract：:Nuclear magnetic resonance (NMR) imaging of perfluorocarbon (PFC) emulsions and neat liquids has shown potential for in vivo oxygen imaging in blood and organ tissue. PFC compounds exhibit complicated NMR spectra caused by chemical shifts and spin-spin couplings which can lead to artifacts and degraded spatial resolut...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595960
更新日期：1986-07-01 00:00:00
abstract：PURPOSE:To quantify the needle tip detection errors in ultrasound images due to bevel-tip orientation in relation to the location on template grid. METHODS:Transrectal ultrasound (TRUS) system (BK Medical) with physical template grid and 18-gauge bevel-tip (20-deg beveled angle) brachytherapy needle (Bard Medical, Cov...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734916
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Conformal SBRT plans for Lung cancer with static gantry angles are ideal candidates for applying motion tracking because of: (1) better dosimetric conformity with reduced target margin and (2) easier and more faithful target tracking without intensity modulation. This work is to demonstrate that by delivering t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734998
更新日期：2012-06-01 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
pub_type： 杂志文章
doi：10.1118/1.594744
更新日期：1980-09-01 00:00:00
abstract：PURPOSE:To develop and validate a multivariate statistical method to optimize scanning parameters for material quantification in spectral x-rayimaging. METHODS:An optimization metric was constructed by extensively sampling the thickness space for the expected number of counts for m (two or three) materials. This resul...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734708
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:To evaluate if the recently described problems with the calibration of jaws at Varian linear accelerators can be detected with the DAVID system. METHODS:Recently Varian Clinac field size issues resulted in a widespread medical device correction notice, stating that incorrect jaw positioning due to excessive co...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736189
更新日期：2012-06-01 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
pub_type： 杂志文章
doi：10.1118/1.4897242
更新日期：2014-11-01 00:00:00
abstract：PURPOSE:The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. METHODS:The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Co...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3218767
更新日期：2009-10-01 00:00:00
abstract：:The American Association of Physicists in Medicine Radiation Therapy Committee Task Group 36 report (TG-36) provides guidelines for managing radiation therapy of pregnant patients. Included in the report are data that can be used to estimate the dose to the fetus. The purpose of this study is to evaluate the accuracy ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2710332
更新日期：2007-04-01 00:00:00
abstract：PURPOSE:Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3519873
更新日期：2011-01-01 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
pub_type： 杂志文章
doi：10.1118/1.596610
更新日期：1991-09-01 00:00:00
abstract：:A calculation is described that enables the rapid assessment of dose rate at various points of interest within the eye (lens, optic nerve, etc.) for the treatment of choroidal melanoma by plaque therapy. 125I seeds are used as the radiation source. The location of the plaque and its associated seeds relative to the ey...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596234
更新日期：1988-05-01 00:00:00
abstract：:Two new liquid ionization chamber (LIC) designs, consisting of cylindrical and plane-parallel configurations, are presented. They are designed to be suitable for high-precision measurements of absorbed dose-to-water at dose rates and photon energies typical for LDR intermediate photon energy brachytherapy sources. The...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598268
更新日期：1998-06-01 00:00:00
