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 multiple metastases patients were planned (Eclipse RapidArc AAA algorithm, v8.6.15) using VMAT (1-6 noncoplanar arcs), dynamic conformal arc (DCA, ∼4 arcs), and IMRT (nine static fields). All plans were evaluated according to a conformity index (CI), healthy brain tissue doses and volumes, and the dose to organs at risk. A 2D dose distribution was measured (Varian Novalis Tx, HD120 MLC, 1000 MU/min, 6 MV beam) for the ∼4 arc VMAT treatment plans using calibrated film dosimetry. RESULTS:The CI (0-1 best) average for all plans was best for ∼4 noncoplanar arc VMAT at 0.86 compared with ∼0.78 for IMRT and a single arc VMAT and 0.68 for DCA. The volumes of healthy brain receiving 50% of the prescribed target coverage dose or more (V(50%)) were lowest for the four arc VMAT [RA(4)] and DCA plans. The average ratio of the V(50%) for the other plans to the RA(4) V(50%) were 1.9 for a single noncoplanar arc VMAT [RA(1nc)], 1.4 for single full coplanar arc VMAT [RA(1f)] and 1.3 for IMRT. The V(50%) improved significantly for single isocenter multiple metastases plan when two noncoplanar VMAT arcs were added to a full single coplanar one. The maximum dose to 5 cc of the outer 1 cm rim of healthy brain which one may want to keep below nonconsequential doses of 300-400 cGy, was 2-3 times greater for IMRT, RA(1nc) and RA(1f) plans compared with the multiple noncoplanar arc DCA and RA(4) techniques. Organs at risk near (0-4 mm) to targets were best spared by (i) single noncoplanar arcs when the targets are lateral to the organ at risk and (ii) by skewed nonvertical planes of IMRT fields when the targets are not lateral to the organ at risk. The highest dose gradient observed between an organ at risk and a target at the edge of a VMAT arc plane or plane of IMRT fields was 17%/mm. The average absolute percent difference between the measured and calculated central axis dose for all the VMAT plans was 3.6 ± 2.2%. The measured perpendicular profile widths and shifts were on average within 0.5 mm of planned values. The average total MUs for VMAT plans was double the DCA average and similar to the IMRT average. CONCLUSIONS:For the aforementioned planning and delivery system and cranial lesions greater than 7 mm in diameter, multiple noncoplanar arc VMAT consistently provides accurate and high quality cranial radiosurgery dose distributions with low doses to healthy brain tissue and high dose conformity to the target. These qualities may make multiple noncoplanar arc VMAT suitable for a greater range of prescription doses or larger and more irregular lesions. For smaller and/or rounder lesions there are other clinically acceptable treatment techniques that may involve fewer couch angles or arcs and reduce treatment times.
journal_name
Med Physjournal_title
Medical physicsauthors
Audet C,Poffenbarger BA,Chang P,Jackson PS,Lundahl RE,Ryu SI,Ray GRdoi
10.1118/1.3641874subject
Has Abstractpub_date
2011-11-01 00:00:00pages
5863-72issue
11eissn
0094-2405issn
2473-4209journal_volume
38pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:It is important for many quantitative brain studies to label meaningful anatomical regions in MR brain images. However, due to high complexity of brain structures and ambiguous boundaries between different anatomical regions, the anatomical labeling of MR brain images is still quite a challenging task. In many ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4940399
更新日期:2016-02-01 00:00:00
abstract::The synchronization of dynamic multileaf collimator (DMLC) response with respiratory motion is critical to ensure the accuracy of DMLC-based four dimensional (4D) radiation delivery. In practice, however, a finite time delay (response time) between the acquisition of tumor position and multileaf collimator response ne...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1915017
更新日期:2005-06-01 00:00:00
abstract::A number of relocatable head fixation systems have become commercially available or developed in-house to perform fractionated stereotactic radiotherapy (SRT) treatment. The uncertainty usually quoted for the target repositioning in SRT is over 2 mm, more than twice that of stereotactic radiosurgery (SRS) systems. Thi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598930
更新日期:2000-04-01 00:00:00
abstract:PURPOSE:The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides exce...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914860
更新日期:2015-04-01 00:00:00
abstract:PURPOSE:The goal of this work is to propose a new multichannel method correcting for systematic thickness disturbances and to evaluate its precision in relevant radiation dosimetry applications. METHODS:The eigencolor ratio technique is introduced and theoretically developed to provide a method correcting for thicknes...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14742
更新日期:2021-02-01 00:00:00
abstract:PURPOSE:As hypoxic cells are more resistant to photon radiation, it is desirable to obtain information about the oxygen distribution in tumors prior to the radiation treatment. Noninvasive techniques are currently not able to provide reliable oxygenation maps with sufficient spatial resolution; therefore mathematical m...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4812431
更新日期:2013-08-01 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
pub_type: 杂志文章
doi:10.1118/1.3132305
更新日期:2009-07-01 00:00:00
abstract::The dose distributions in the bifurcated vessels treated with intravascular brachytherapyline sources are complicated and depend on the bifurcation geometry consisting of a main and a branch vessel at different angles. To investigate the dosimetric effects at the bifurcation, calculations were performed on branching v...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1582813
更新日期:2003-07-01 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
pub_type: 杂志文章
doi:10.1118/1.595963
更新日期:1986-01-01 00:00:00
abstract:PURPOSE:This study (1) examines a variety of real-world cases where systematic errors were not detected by widely accepted methods for IMRT/VMAT dosimetric accuracy evaluation, and (2) drills-down to identify failure modes and their corresponding means for detection, diagnosis, and mitigation. The primary goal of detai...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4826166
更新日期:2013-11-01 00:00:00
abstract:PURPOSE:The aim of this study was to evaluate a surrogate-driven motion model based on four-dimensional computed tomography that is able to predict CT volumes corresponding to arbitrary respiratory phases. Furthermore, the comparison of three different driving surrogates is examined and the feasibility of using the mod...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12243
更新日期:2017-06-01 00:00:00
abstract:PURPOSE:A novel 3D printing method has been developed, which employs human CT images to construct patient specific phantoms by controlling the filament extrusion rate. METHODS:An in-house software was developed comprising pixel-by-pixel (PbP) reading of the Hounsfield Units (HU) values in the original patient DICOM im...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13154
更新日期:2018-10-01 00:00:00
abstract::Accurate segmentation of microcalcifications in mammography is crucial for the quantification of morphologic properties by features incorporated in computer-aided diagnosis schemes. A novel segmentation method is proposed implementing active rays (polar-transformed active contours) on B-spline wavelet representation t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2991286
更新日期:2008-11-01 00:00:00
abstract::The measurement of the radioactivity administered to the patient is one of the major components of 90Y microsphere liver brachytherapy. The activity of 90Y microspheres in a glass delivery vial was measured in a dose calibrator. The calibration value to use for 90Y in the dose calibrator was verified using an activity...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2731034
更新日期:2007-06-01 00:00:00
abstract:PURPOSE:Stray neutron radiation is of concern after radiation therapy, especially in children, because of the high risk it might carry for secondary cancers. Several previous studies predicted the stray neutron exposure from proton therapy, mostly using Monte Carlo simulations. Promising attempts to develop analytical ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4829512
更新日期:2013-12-01 00:00:00
abstract:PURPOSE:To generate hybrid VMAT-IMRT treatment plans by utilizing an IMRT beam-angle-optimality (BAO) search under a commercially available TPS without the aid of custom optimization software or high performance computing. METHODS:The high dose modulation provided by IMRT beams can be exploited to improve the quality ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735712
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To evaluate the accuracy of skin dose determination for composite multibeam 3D conformal radiation therapy (3DCRT) and intensity modulated radiation therapy (IMRT) treatments using optically stimulated luminescent dosimeters (OSLDs) and Eclipse treatment planning system. METHODS:Surface doses measured by OSLDs...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4890795
更新日期:2014-08-01 00:00:00
abstract::The use of electronic portal imaging devices (EPIDs) is a promising method for the dosimetric verification of external beam, megavoltage radiation therapy-both pretreatment and in vivo. In this study, a previously developed EPID back-projection algorithm was modified for IMRT techniques and applied to an amorphous sil...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2147744
更新日期:2006-02-01 00:00:00
abstract::Calibration of an imported strontium-90 ophthalmic applicator at the U.S. National Bureau of Standards (now the National Institute of Standards and Technology) has disclose a significant discrepancy in dose rate calibration (32%-35%) with that quoted by the manufacturer. The University of Wisconsin has investigated th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596702
更新日期:1991-03-01 00:00:00
abstract:PURPOSE:To Validate Brainlab-ExacTrac IGRT with Dot-Decimal electron compensator(BolusECT) for accurate patient positioning. METHODS:Dot-Decimal electron compensators(BolusECT) are used to achieve conformal dose distributions and greater sparing to normal structures for cases with varying patient contours and treated ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734881
更新日期:2012-06-01 00:00:00
abstract::Intensity modulated radiotherapy (IMRT) requires extensive knowledge of multileaf collimator (MLC) leaf positioning accuracy, precision, and long-term reproducibility. We have developed a technique to efficiently measure the absolute position of each MLC leaf, over the range of leaf positions utilized in IMRT, based o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1564091
更新日期:2003-05-01 00:00:00
abstract::The hybrid algorithms developed recently for the reconstruction of fan-beam images possess computational and noise properties superior to those of the fan-beam filtered backprojection (FFBP) algorithm. However, the hybrid algorithms cannot be applied directly to a halfscan fan-beam sinogram because they require knowle...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1288239
更新日期:2000-09-01 00:00:00
abstract::Some limitations of conventional two-dimensional computer programs used to plan radiation therapy are presented. These include: a lack of involvement in defining the clinical problem; deficiencies in the algorithms for computing dose; failure to compute dose throughout the volume of interest; an inability to handle tr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595226
更新日期:1982-07-01 00:00:00
abstract:PURPOSE:The authors investigate performance of thin-film cadmium telluride (CdTe) in detecting high-energy (6 MV) x rays. The utilization of this material has become technologically feasible only in recent years due to significant development in large area photovoltaic applications. METHODS:The CdTe film is combined w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3438082
更新日期:2010-08-01 00:00:00
abstract:PURPOSE:The objectives are: (i) assess the development of the impedance of some arteries during the first decades of life; (ii) determine the influence of pulse rate in arterial impedance; (iii) compare the structure of some arterial segments with optimized structures with respect to blood flow; and (iv) explain the el...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4876379
更新日期:2014-06-01 00:00:00
abstract::Effective radioimmunotherapy may depend on a priori knowledge of the radiation absorbed dose distribution obtained by trace imaging activities administered to a patient before treatment. A new, fast, and effective treatment planning approach is developed to deal with a heterogeneous activity distribution. Calculation ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598422
更新日期:1998-11-01 00:00:00
abstract:PURPOSE:The x-ray performance evaluation of digital x-ray detectors is based on the calculation of the modulation transfer function (MTF), the noise power spectrum (NPS), and the resultant detective quantum efficiency (DQE). The flat images used for the extraction of the NPS should not contain any fixed pattern noise (...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3664003
更新日期:2011-12-01 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::Setting up and maintaining video display monitors properly will help to reduce display variation and improve overall presentation of the radiological image. Display monitor gray-scale characteristics were examined using the SMPTE test pattern. This test pattern may be used as a standard for adjusting brightness and co...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596846
更新日期:1992-05-01 00:00:00
abstract::Optimal visualization of moving structures such as the heart and coronary arteries using digital radiographic imaging systems is a difficult problem that can involve tradeoffs between temporal, spatial, and density resolution. The motion dependence of four angiographic measures of vessel dimensions is given and demons...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595651
更新日期:1985-11-01 00:00:00