Abstract:
:An important aspect of heavy charged particle radiotherapy is its ability to localize dose to the target volume. Current techniques generally employ beam delivery schemes which use range modulated beams in which the Bragg peak is spread out over a range of depths. The range modulation is constant over the entire beam cross section. This paper examines the potential gain from the use of variable range modulation over the beam cross section which can be achieved through beam scanning. An analytic technique has been developed to calculate a gain factor, related to integral dose, for a number of different charged particle beams. The dependence of the gain factor on tumor depth, diameter, and size has been examined. These analytic results have been compared with computer calculations of treatment plans simulating beam scanning and fixed modulation delivery techniques for actual clinical cases. The rationale for beam scanning, and its potential impact on tumor control is discussed.
journal_name
Med Physjournal_title
Medical physicsauthors
Goitein M,Chen GTdoi
10.1118/1.595419subject
Has Abstractpub_date
1983-11-01 00:00:00pages
831-40issue
6eissn
0094-2405issn
2473-4209journal_volume
10pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:On-board MRI can provide superb soft tissue contrast for improving liver SBRT localization. However, the availability of on-board MRI in clinics is extremely limited. On the contrary, on-board kV imaging systems are widely available on radiotherapy machines, but its capability to localize tumors in soft tissue ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12998
更新日期:2018-07-01 00:00:00
abstract:PURPOSE:Imaging the knee under realistic load-bearing conditions can be carried out in a horizontal plane using a C-arm CT scanner. Human subjects can be scanned in a standing position and acquired data successfully reconstructed. However, reconstructing this data is a challenge due to significant artifacts that are in...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736213
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) IMAT solution. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3622672
更新日期:2011-09-01 00:00:00
abstract::A fully automatic radiophotoluminescent glass rod dosimeter (GRD) system has recently become commercially available. This article discusses the dosimetric properties of the GRD including uniformity and reproducibility of signal, dose linearity, and energy and directional dependence in high-energy photon beams. In addi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1758351
更新日期:2004-07-01 00:00:00
abstract::A conceptual design is presented showing that, by judiciously choosing the beryllium target thickness and the backstop material, improvements can be achieved in dose-rate, skin sparing, and penetration of neutron beams generated by the same proton accelerator. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594748
更新日期:1980-09-01 00:00:00
abstract::To develop volumetric micro-CT fluoroscopy for small animal imaging, we have proposed a cone-beam system with multiple x-ray sources. In this paper, we extend Parker's single-source half-scan weighting scheme to the case of an odd number of x-ray sources that are equiangularly distributed, and apply it for half-scan F...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1381549
更新日期:2001-07-01 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::The physical characteristics of the interactions of megavoltage photons and electrons with matter provide distinct advantages, relative to low-energy (orthovoltage) x rays, that lead to better radiation dose distributions in patients. Use of these high-energy radiations has resulted in better patient care, which has b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596779
更新日期:1992-07-01 00:00:00
abstract:PURPOSE:We propose a new method for efficient particle transportation in voxelized geometry for Monte Carlo simulations. We describe its use for calculating dose distribution in CT images for radiation therapy. MATERIAL AND METHODS:The proposed approach, based on an implicit volume representation named segmented volum...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2884854
更新日期:2008-04-01 00:00:00
abstract::To more accurately and precisely delineate a tumor in a 3D PET image, we proposed a novel, semi-automatic, two-stage method by utilizing an adaptive region-growing algorithm and a dual-front active contour model. First, a rough region of interest (ROI) is manually drawn by a radiation oncologist that encloses a tumor....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2956713
更新日期:2008-08-01 00:00:00
abstract:PURPOSE:The Synchrony respiratory motion tracking of the CyberKnife system purports to provide real-time tumor motion compensation during robotic radiosurgery. Such a complex delivery system requires thorough quality assurance. In this work, RADPOS applicability as a dose and position quality assurance tool for CyberKn...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13102
更新日期:2018-07-25 00:00:00
abstract::The 1983 AAPM protocol for the determination of absorbed dose from high-energy photon and electron beams recommends using Pion (the reciprocal of collection efficiency), as determined by the two-voltage technique, to correct for recombination losses in ionization chambers. Methods and data for the determination of ion...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595574
更新日期:1984-11-01 00:00:00
abstract::Over the past decade, computed tomography (CT) theory, techniques and applications have undergone a rapid development. Since CT is so practical and useful, undoubtedly CT technology will continue advancing biomedical and non-biomedical applications. In this outlook article, we share our opinions on the research and de...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.2836950
更新日期:2008-03-01 00:00:00
abstract:PURPOSE:Diffusion magnetic resonance imaging (MRI) in combination with functional MRI promises a whole new vista for scientists to investigate noninvasively the structural and functional connectivity of the human brain-the human connectome, which had heretofore been out of reach. As with other imaging modalities, diffu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3700166
更新日期:2012-05-01 00:00:00
abstract::An improved reconstructed stereoscopic x-ray image display system, based on the principle of binocular parallax, is described. Pulse-synchronized operation of two triode x-ray tubes and one plumbicon TV camera is employed to separate the left and right images for presentation to the two eyes, respectively. The princip...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595365
更新日期:1983-09-01 00:00:00
abstract:PURPOSE:Intracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the ski...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3429089
更新日期:2010-06-01 00:00:00
abstract:PURPOSE:Since the introduction of clinical x-ray phase-contrast mammography (PCM), a technique that exploits refractive-index variations to create edge enhancement at tissue boundaries, a number of optimization studies employing physical image-quality metrics have been performed. Ideally, task-based assessment of PCM w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3676183
更新日期:2012-02-01 00:00:00
abstract:PURPOSE:Mammography is known to be one of the most difficult radiographic exams to interpret. Mammography has important limitations, including the superposition of normal tissue that can obscure a mass, chance alignment of normal tissue to mimic a true lesion and the inability to derive volumetric information. It has b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3562901
更新日期:2011-04-01 00:00:00
abstract::This article provides a quantitative evaluation of Varian Medical Systems' beam matching procedure. A one-dimensional y analysis is employed to investigate the level of agreement of matched beams. A customized concept of one-dimensional gamma evaluation was designed. Our algorithm first performs a "local" fit of the r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2745239
更新日期:2007-07-01 00:00:00
abstract::Skin entrance doses of patients undergoing interventional x-ray procedures are capable of causing skin damage and should be monitored routinely. Single TLD chips are not suitable because the location of maximum skin exposure cannot be predicted. Most photographic films are too sensitive at diagnostic x-ray energies fo...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597973
更新日期:1997-10-01 00:00:00
abstract::The ability to control thermal drifts is essential in operating a calorimeter. We investigated a thermal enclosure, which envelops the calorimeter with temperature-regulated air, thus thermally isolating the calorimeter from the room. The desired temperature in the enclosure is controlled by a control circuit and a th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595760
更新日期:1985-05-01 00:00:00
abstract:PURPOSE:Dual-energy computed tomography and dual-energy cone-beam computed tomography (DE-CBCT) are promising modalities for applications ranging from vascular to breast, renal, hepatic, and musculoskeletal imaging. Accordingly, the optimization of imaging techniques for such applications would benefit significantly fr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736420
更新日期:2012-08-01 00:00:00
abstract::The Monte Carlo (MC) method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with conventional, deterministic dose algorithms. Despite its p...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.2795842
更新日期:2007-12-01 00:00:00
abstract:PURPOSE:Wide-angle free-air chambers (WAFACs) are used as primary standard measurement devices for establishing the air-kerma strength of low-energy, low-dose rate brachytherapy seeds. The National Research Council of Canada (NRC) is commissioning a primary standard wide-angle free-air chamber (NRC WAFAC) to serve the ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4951727
更新日期:2016-07-01 00:00:00
abstract::Current methods for imaging joint motion are limited to either two-dimensional (2D) video fluoroscopy, or to animated motions from a series of static three-dimensional (3D) images. 3D movement patterns can be detected from biplane fluoroscopy images matched with computed tomography images. This involves several x-ray ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2000647
更新日期:2005-09-01 00:00:00
abstract:PURPOSE:Currently applied calibration approaches lead to satisfying 3D roadmapping overlay and 3D reconstruction accuracies; however, the required calibration times are extensive. The aim of this paper is the introduction of a novel model-based approach for geometric system calibrations, leading to a significant reduct...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4931964
更新日期:2015-11-01 00:00:00
abstract::A tomographic attachment was designed and developed that attaches to our existing simulator. The film tomograms obtained with the aid of this device exhibit very low geometrical distortion and good contrast and resolution for the objects used in this investigation. In addition, our results to date show that adjacent a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594662
更新日期:1980-03-01 00:00:00
abstract:PURPOSE:The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor. METHODS:The authors ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4953186
更新日期:2016-07-01 00:00:00
abstract::Quantitative evaluation of cardiac image data obtained using multidetector row computed tomography (CT) is compromised by partial scan reconstructions, which improve the temporal resolution but significantly increase image-to-image CT number variations for a fixed region of interest compared to full reconstruction ima...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2805476
更新日期:2007-12-01 00:00:00
abstract::In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595546
更新日期:1984-09-01 00:00:00