Abstract:
PURPOSE:In dose guided radiation therapy, incident fluence is one of the important parameters for both influence verification and dose reconstruction. The objective of this investigation was to develop a method to obtain the incident fluence for dose reconstruction in dose guided radiation therapy (DGRT). METHODS:An incident fluence reconstruction model based on Monte Carlo Finite-size pencil beam (MCFSPB) model and "Matthew Effect" Conjugate-gradient (CG) algorithm was developed, where the MCFSPB model was developed by FDS Team (www.fds.org.cn) and the "Matthew Effect" was proposed to advance the accuracy of CG lgorithm. Then, by measuring dose with amorphous silicon flat panel (a-Si flat panel), the incident fluence was unfolded. An artifical head phantom was used to test sample. By using the incident fluence to dose calculation with MCFSPB, the 2D and 3D dose was also reconstructed and compared with the measurement dose and the planing dose respectively. The Passing Rate of Dose Difference (PRDD) in 3% was used to learn the accuracy. RESULTS:Two representative cases (6MV and 10MV) with both five beams were used for beam-by-beam verification, and the corresponding incident fluence was obtained. By comparing the measurement dose with the calculation dose on measurement plane, the results showed that the PRDD (3%) in field was 100%. And by comparing 3D plannning dose with 3D reconstructed dose, the results indicated that the PRDD (3%) in field was 95%∼98%. CONCLUSIONS:The incident fluence reconstruction model based on MCFSPB model and "Matthew Effect" Conjugate-gradient algorithm was developed. The tested results indicated its accuracy. This study is expected to be applied to 3D dose reconstruction and 3D dosimetric verification in DGRT. Supported by the National Natural Science Foundation under grant No.30900386 and the National Science Foundation of Anhui Province (Nos.090413095 and 111040606Q55).
journal_name
Med Physjournal_title
Medical physicsauthors
Li G,Wu Y,FDS Team.doi
10.1118/1.4735593subject
Has Abstractpub_date
2012-06-01 00:00:00pages
3821issue
6Part18eissn
0094-2405issn
2473-4209journal_volume
39pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4894728
更新日期:2014-10-01 00:00:00
abstract::The assessment of the radiation dose to internal organs or to an embryo or fetus is required on occasion for risk assessment or for comparing imaging studies. Limited resources hinder the ability to accurately assess the radiation dose received to locations outside the tissue volume actually scanned during computed to...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1312809
更新日期:2000-10-01 00:00:00
abstract::IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1477415
更新日期:2002-06-01 00:00:00
abstract:PURPOSE:One technical barrier to patient-specific computed tomography (CT) dosimetry has been the lack of computational tools for the automatic patient-specific multi-organ segmentation of CT images and rapid organ dose quantification. When previous CT images are available for the same body region of the patient, the a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14131
更新日期:2020-06-01 00:00:00
abstract:PURPOSE:The GammaPod is a novel dedicated prone breast stereotactic radiosurgery (SRS) device recently developed at the University of Maryland Medical Center. This device utilizes multiple rotating Co-60 sources to create highly conformal dose distributions for breast treatments, including boosts, partial breast irradi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14197
更新日期:2020-08-01 00:00:00
abstract::Manganese (Mn) is an essential nutrient for growth and development. Unfortunately, overexposure can lead to neurological damage, which is manifested as a movement disorder marked by tremors. Preclinical symptoms have been found in populations occupationally exposed to the element, and it is suggested that in late stag...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1517613
更新日期:2002-11-01 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:Mammographic density of glandular breast tissue has a masking effect that can reduce lesion detection accuracy and is also a strong risk factor for breast cancer. Therefore, accurate quantitative estimation of breast density is clinically important. In this study, we investigate experimentally the feasibility o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13031
更新日期:2018-06-03 00:00:00
abstract:PURPOSE:To track variations in the deformation of the arterial wall noninvasively by estimating the accumulated displacement and strain over a cardiac cycle may provide useful indicators of vascular health. METHODS:In this paper, we propose an approach to track a region of interest (ROI) locally and estimate arterial ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4722746
更新日期:2012-07-01 00:00:00
abstract:PURPOSE:In this article, the authors propose a new gold standard data set for the validation of two-dimensional/three-dimensional (2D/3D) and 3D/3D image registration algorithms. METHODS:A gold standard data set was produced using a fresh cadaver pig head with attached fiducial markers. The authors used several imagin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3553402
更新日期:2011-03-01 00:00:00
abstract::We discuss a formalism for clinical proton beam dosimetry based on the use of ionization chamber absorbed dose-to-water calibration and beam quality correction factors. A quantity kQ, the beam quality correction factor, is defined which corrects the absorbed dose-to-water calibration factor ND,w in a reference beam of...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597768
更新日期:1996-01-01 00:00:00
abstract:PURPOSE:Quantitative cone-beam CT (CBCT) imaging is on increasing demand for high-performance image guided radiation therapy (IGRT). However, the current CBCT has poor image qualities mainly due to scatter contamination. Its current clinical application is therefore limited to patient setup based on only bony structure...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3693050
更新日期:2012-04-01 00:00:00
abstract:PURPOSE:Manual delineation of head and neck (H&N) organ-at-risk (OAR) structures for radiation therapy planning is time consuming and highly variable. Therefore, we developed a dynamic multiatlas selection-based approach for fast and reproducible segmentation. METHODS:Our approach dynamically selects and weights the a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13854
更新日期:2019-12-01 00:00:00
abstract:PURPOSE:Because the small-radius photon beams shaped by cones in stereotactic radiosurgery (SRS) lack lateral electronic equilibrium and a detector's finite cross section, direct experimental measurement of dosimetric data for these beams can be subject to large uncertainties. As the dose calculation accuracy of a trea...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3488900
更新日期:2010-10-01 00:00:00
abstract::A new high dose rate 20 mm 32P intravascular brachytherapy (IVB) beta source used with automated stepping has recently been introduced. The AAPM Task Group 60 recommends that beta IVB sources should have well characterized dosimetric parameters in water. In this study, Monte Carlo simulations (MCNPX v 2.4) were used t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1646651
更新日期:2004-03-01 00:00:00
abstract::Stereotactic Body Radiation Therapy (SBRT) is an important form of cancer therapy with increasingly broad application across a spectrum of tumor types in primary and metastatic settings. In this presentation the radiation biology, clinical experience from various trials, and cautionary updates on normal tissue toleran...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735812
更新日期:2012-06-01 00:00:00
abstract::Because of the high energy of the treatment beam, contrast of portal verification films is very poor. A simple contrast enhancement technique is described which we have labeled selective histogram equalization (SHE), to improve visualization of double-exposure portal images and this facilitate the beam verification pr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597085
更新日期:1993-01-01 00:00:00
abstract:PURPOSE:Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. METHODS:In the variational image segmen...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4945046
更新日期:2016-05-01 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::The purpose of this study was to implement the Monte Carlo method for clinical radiotherapy dose calculations. We used the EGS4/BEAM code to obtain the phase-space data for 6-20 MeV electron beams and 4, 6, and 15 MV photon beams for Varian Clinac 1800, 2100C, and 2300CD accelerators. A multiple-source model was used ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598729
更新日期:1999-10-01 00:00:00
abstract::The head-scatter factors H were examined for four different linear accelerators and were found to be similar at field sizes larger than 3 x 3 cm2. Sharply reduced values for small collimator openings were observed for all the accelerators. It is concluded that the head-scatter (or collimator-scatter) factor has two ma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597256
更新日期:1994-01-01 00:00:00
abstract:PURPOSE:The purpose of this study is to estimate the effect of edema, developed during implant procedure, on tumor cell surviving fraction(SF) and tumor control probability(TCP) in the patients of prostate cancer who underwent 131 Cs permanent seed implants. METHODS:The impact of edema on SF and TCP, was calculated us...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735061
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:In photon radiotherapy, respiratory-induced target motion can be accounted for by internal target volumes (ITV) or mid-ventilation target volumes (midV) defined on the basis of four-dimensional computed tomography (4D-CT). Intrinsic limitations of these approaches can result in target volumes that are not repre...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14023
更新日期:2020-04-01 00:00:00
abstract::Dose to the total body from induced radiation resulting from primary exposure to radiotherapeutic beams is not detailed in routine treatment planning though this information is potentially important for better estimates of health risks including secondary cancers. This information can also allow better management of p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1612947
更新日期:2003-10-01 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:To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS:Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4725172
更新日期:2012-07-01 00:00:00
abstract:OBJECTIVE:To develop an anthropomorphic, deformable and multimodal pelvis phantom with positron emission tomography extension for radiotherapy (ADAM PETer). METHODS:The design of ADAM PETer was based on our previous pelvis phantom (ADAM) and extended for compatibility with PET and use in 3T magnetic resonance imaging ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14597
更新日期:2020-11-18 00:00:00
abstract::Radiation sensitive gels have been used as dosimeters for clinical dose verification of different radiation therapy modalities. However, the use of gels is not widespread, because careful techniques are required to achieve the dose precision and accuracy aimed for in clinical dose verification. Here, the introduction ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2712042
更新日期:2007-04-01 00:00:00
abstract::Coherent scattering of x-ray photons leads to the phenomenon of x-ray diffraction, which is widely used for determining atomic structure in materials science. A technique [x-ray diffraction computed tomography (CT)] is described, analogous to conventional CT, in which the x-ray diffraction properties of a stack of two...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596063
更新日期:1987-07-01 00:00:00
abstract:PURPOSE:Adding magnetic resonance (MR)-derived information to standard transrectal ultrasound (TRUS) images for guiding prostate biopsy is of substantial clinical interest. A tumor visible on MR images can be projected on ultrasound (US) by using MR-US registration. A common approach is to use surface-based registratio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4917481
更新日期:2015-05-01 00:00:00