Abstract：
:Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter-relationship among arc range, Multi-Leaf Collimator (MLC) leaf positions and angular dose rate optimizations for IMAT delivery of a concave target. A concave planning target volume (PTV) with central cylindrical organ at risk (OAR) was used in dissecting the inter-relationships. Plans with full and limited arc range were generated using leaf position optimization (LPO) alone, angular dose rate optimization (ADRO) alone or LPO followed by ADRO. Two initial IMAT arcs were conformal avoidance arcs created with 5° angular increments where MLC leaf positions were determined from the beams eye view to irradiate the PTV but avoid the OAR. The objective function value (evaluating dose to PTV and OAR), a conformity index, dose homogeneity index, mean dose to OAR and normal tissues were computed and used to evaluate the treatment plans. Dose rate variations and MLC leaf movements as a function of gantry angle were examined in this approach. The results demonstrate that LPO followed by ADRO provided the lowest objective function values, best conformity and dose homogeneity indices, and third in mean dose to OAR and normal tissues for the complete arc range. Future work will address different strategies for simultaneously optimizing both the MLC leaf positions and the variable angular dose rate for IMAT delivery and compare single and multiple arc plans.
journal_name
Med Physjournal_title
Medical physicsauthors
Oliver M,Chen J,Wong Edoi
10.1118/1.2965975subject
Has Abstractpub_date
2008-07-01 00:00:00pages
3412issue
7Part3eissn
0094-2405issn
2473-4209journal_volume
35pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast impl...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3006151
更新日期：2008-12-01 00:00:00
abstract：PURPOSE:The accuracy of a six degree of freedom (6DoF) couch was evaluated using a novel method. METHODS:Cone beam CT (CBCT) images of a 3D phantom (IsoCal) were acquired with different, known combinations of couch pitch and roll angles. Pitch and roll angles between the maximum allowable values of 357 and 3 degrees w...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12342
更新日期：2017-08-01 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：:Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared wit...
journal_title：Medical physics
pub_type： 临床试验,杂志文章
doi：10.1118/1.1800712
更新日期：2004-11-01 00:00:00
abstract：PURPOSE:High-dose-rate brachytherapy (HDR-BT) is a treatment option for malignant skin diseases compared to external beam radiation therapy, HDR-BT provides improved target coverage, better organ sparing, and has comparable treatment times. This is especially true for large clinical targets with complex topologies. To ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13975
更新日期：2020-03-01 00:00:00
abstract：PURPOSE:The collimator monitoring fill factor (CM-FF) introduced by Stelljes et al. (2017) and the FWHM fill factor (FWHM-FF) introduced by Gago-Arias et al. (2012) were determined using the measured photon fluence response functions of various 2D-arrays. The error detection capabilities of 2D-arrays were studied by co...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13417
更新日期：2019-04-01 00:00:00
abstract：PURPOSE:The aim of this study is to understand the characteristics of secondary electrons generated from the interaction of gold nanoparticles (GNPs) with x-rays as a function of nanoparticle size and beam energy and thereby further the understanding of GNP-enhanced radiotherapy. METHODS:The effective range, deflectio...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3539623
更新日期：2011-02-01 00:00:00
abstract：:We are developing a computer program for automated detection of clustered microcalcifications on mammograms. In this study, we investigated the effectiveness of a signal classifier based on a convolution neural network (CNN) approach for improvement of the accuracy of the detection program. Fifty-two mammograms with c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597428
更新日期：1995-10-01 00:00:00
abstract：PURPOSE:The management of thoracic malignancies with radiation therapy is complicated by continuous target motion. In this study, a real time motion analysis approach is proposed to improve the accuracy of patient setup. METHODS:For 11 lung cancer patients a long training fluoroscopy was acquired before the first trea...
journal_title：Medical physics
pub_type： 临床试验,杂志文章
doi：10.1118/1.4794489
更新日期：2013-04-01 00:00:00
abstract：:With the increasing complexity of dose patterns external beam radiotherapy, there is a great need for new types of dosimeters. We studied the first prototype of a new dosimeter array consisting of water-equivalent plastic scintillating fibers for dose measurement in external beam radiotherapy. We found that this array...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2719363
更新日期：2007-05-01 00:00:00
abstract：PURPOSE:This article presents a new reconstruction method for 3D imaging using a multiple 360 degrees circular orbit cone beam CT system, specifically a way to combine 3D volumes reconstructed with each orbit. The main goal is to improve the noise performance in the combined image while avoiding cone beam artifacts. M...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3484058
更新日期：2010-10-01 00:00:00
abstract：:Reconstruction of electron spectra of medical accelerators from measured depth dose distributions is an attractive tool for commissioning of a Monte Carlo treatment planning system. However, the reconstruction method is an inverse radiation transport problem which is poorly conditioned, in the sense it may become unst...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1461840
更新日期：2002-04-01 00:00:00
abstract：:Deformable image registration is an important tool for image-guided radiotherapy. Physics-model-based deformable image registration using finite element analysis is one of the methods currently being investigated. The calculation accuracy of finite element analysis is dependent on given boundary conditions, which are ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1774131
更新日期：2004-09-01 00:00:00
abstract：PURPOSE:The efficiency of radioembolization procedures could be greatly enhanced if results of the 99m Tc-MAA pretreatment procedure were immediately available in the interventional suite, enabling 1-day procedures as a result of direct estimation of the hepatic radiation dose and lung shunt fraction. This would, howev...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13253
更新日期：2019-01-01 00:00:00
abstract：PURPOSE:To investigate the sensitivity of the plan-class specific correction factor to dose distributions in composite nonstandard field dosimetry. METHODS:A cylindrical water-filled PMMA phantom was constructed at the center of which reference absorbed dose could be measured. Ten different TomoTherapy(®)-based IMRT f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3669487
更新日期：2012-01-01 00:00:00
abstract：PURPOSE:A critical step in adaptive radiotherapy (ART) workflow is deformably registering the simulation CT with the daily or weekly volumetric imaging. Quantifying the deformable image registration accuracy under these circumstances is a complex task due to the lack of known ground-truth landmark correspondences betwe...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12321
更新日期：2017-08-01 00:00:00
abstract：:Three-dimensional water phantoms are routinely used when acquiring the data necessary to commission medical linear accelerators. A new water phantom controller has been developed at our institution that is unique in several aspects. The water phantom controller is based on an IBM XT compatible computer. This has been ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596414
更新日期：1989-01-01 00:00:00
abstract：:The purpose of this study was to investigate the effect of z overscanning on eye lens dose and effective dose received by pediatric patients undergoing head CT examinations. A pediatric patient study was carried out to obtain the exposure parameters and data regarding the eye lens position with respect to imaged volum...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2207212
更新日期：2006-07-01 00:00:00
abstract：PURPOSE:Two ultra-high-resolution (UHR) computed tomography (CT) scanners are clinically available. One is achieved by a CT system with a 0.25 mm × 160 row detector (Detector-UHR), whereas the other is with a 0.6 mm × 32 row detector with in-plane comb filtering in a dual source CT (Comb-UHR). We compared radiation dos...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13949
更新日期：2020-02-01 00:00:00
abstract：PURPOSE:New preclinical image-guided irradiators and treatment planning systems represent a huge progress in radiobiology. Nevertheless, quality control of preclinical treatments is not as advanced as in clinical radiotherapy and in vivo dosimetry is less developed. In this study, we evaluate the use of a scintillating...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13903
更新日期：2020-01-01 00:00:00
abstract：PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735656
更新日期：2012-06-01 00:00:00
abstract：:Current MRI nonuniformity correction techniques are reviewed and investigated. Many approaches are used to remedy this artifact, but it is not clear which method is the most appropriate in a given situation, as the applications have been with different MRI coils and different clinical applications. In this work four w...
journal_title：Medical physics
pub_type： 杂志文章,评审
doi：10.1118/1.598357
更新日期：1998-09-01 00:00:00
abstract：:The physical imaging performance of ST-V, ST-VA, and ST-VN computed radiography image plates, read with a Philips AC3 acquisition system, was investigated at 70 kVp with 0.5 mm of copper beam filtration for four different entrance air kerma values: 0.5, 2.6, 26, and 260 micro Gy. Measurements included characteristic r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598412
更新日期：1998-11-01 00:00:00
abstract：:The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10 x 10 cm2 collimator setting, by varying source-to-det...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1650563
更新日期：2004-04-01 00:00:00
abstract：PURPOSE:The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. METHODS:The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4918321
更新日期：2015-05-01 00:00:00
abstract：PURPOSE:Several new technologies for single photon emission computed tomography (SPECT) instrumentation with parallel-hole collimation have been proposed to improve detector sensitivity and signal collection efficiency. Benefits from improved signal efficiency include shorter acquisition times and lower dose requiremen...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4897567
更新日期：2014-11-01 00:00:00
abstract：PURPOSE:Design and optimization of medical imaging systems benefit from accurate theoretical modeling that identifies the physical factors governing image quality, particularly in the early stages of system development. This work extends Fourier metrics of imaging performance and detectability index (d') to tomosynthes...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3560428
更新日期：2011-04-01 00:00:00
abstract：:This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyeth...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596084
更新日期：1987-03-01 00:00:00
abstract：:An automated technique has been developed for the verification of treatment field size and shape in external beam radiation therapy. Portal images from film or digital on-line imaging system are analyzed, and basic parameters are derived to describe the field size and shape from the contour points on the field boundar...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597017
更新日期：1993-05-01 00:00:00
abstract：:Automatic exposure control (AEC) systems have been developed by computed tomography (CT) manufacturers to improve the consistency of image quality among patients and to control the absorbed dose. Since a multichannel helical CT scan may easily increase individual radiation doses, this technical improvement is of speci...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2746492
更新日期：2007-07-01 00:00:00
