Abstract:
PURPOSE:When an intensity-modulated radiation beam is delivered to a moving target, the interplay effect between dynamic beam delivery and the target motion due to miss-synchronization can cause unpredictable dose delivery. The portal dose image in electronic portal imaging device (EPID) represents radiation attenuated and scattered through target media. Thus, it may possess information about delivered radiation to the target. Using a continuous scan (cine) mode of EPID, which provides temporal dose images related to target and beam movements, the authors' goal is to perform four-dimensional (4D) dose reconstruction. METHODS:To evaluate this hypothesis, first, the authors have derived and subsequently validated a fast method of dose reconstruction based on virtual beamlet calculations of dose responses using a test intensity-modulated beam. This method was necessary for processing a large number of EPID images pertinent for four-dimensional reconstruction. Second, cine mode acquisition after summation over all images was validated through comparison with integration mode acquisition on EPID (IAS3 and aS1000) for the test beam. This was to confirm the agreement of the cine mode with the integrated mode, specifically for the test beam, which is an accepted mode of image acquisition for dosimetry with EPID. Third, in-phantom film and exit EPID dosimetry was performed on a moving platform using the same beam. Heterogeneous as well as homogeneous phantoms were used. The cine images were temporally sorted at 10% interval. The authors have performed dose reconstruction to the in-phantom plane from the sorted cine images using the above validated method of dose reconstruction. The reconstructed dose from each cine image was summed to compose a total reconstructed dose from the test beam delivery, and was compared with film measurements. RESULTS:The new method of dose reconstruction was validated showing greater than 95.3% pass rates of the gamma test with the criteria of dose difference of 3% and distance to agreement of 3 mm. The dose comparison of the reconstructed dose with the measured dose for the two phantoms showed pass rates higher than 96.4% given the same criteria. CONCLUSIONS:Feasibility of 4D dose reconstruction was successfully demonstrated in this study. The 4D dose reconstruction demonstrated in this study can be a promising dose validation method for radiation delivery on moving organs.
journal_name
Med Physjournal_title
Medical physicsauthors
Yeo IJ,Jung JW,Yi BY,Kim JOdoi
10.1118/1.4799941subject
Has Abstractpub_date
2013-05-01 00:00:00pages
051702issue
5eissn
0094-2405issn
2473-4209journal_volume
40pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4772075
更新日期:2013-01-01 00:00:00
abstract:PURPOSE:To present the results of a patient dose evaluation program in pediatric cardiology and propose local diagnostic reference levels (DRLs) for different types of procedure and age range, in addition to suggesting approaches to correlate patient dose values with patient weight. This study was the first conducted i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4905116
更新日期:2015-02-01 00:00:00
abstract::We are developing computerized methods for characterizing the bone texture pattern from digitized skeletal radiographs. For this method to be useful clinically, it must be able to distinguish between weak and strong bone under the range of exposure conditions potentially encountered in the clinical setting. In this st...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598858
更新日期:2000-01-01 00:00:00
abstract::Frequent and repeated imaging procedures such as those performed in image-guided radiotherapy (IGRT) programs may add significant dose to radiosensitive organs of radiotherapy patients. It has been shown that kV-CBCT results in doses to bone that are up to a factor of 3-4 higher than those in surrounding soft tissue. ...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.3014197
更新日期:2008-12-01 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:Due to the low contrast, blurry boundaries, and large amount of shadows in breast ultrasound (BUS) images, automatic tumor segmentation remains a challenging task. Deep learning provides a solution to this problem, since it can effectively extract representative features from lesions and the background in BUS i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13268
更新日期:2019-01-01 00:00:00
abstract:PURPOSE:The repair rate conventionally assumed to be constant during the entire radiation course. However, increasing evidences from animal studies show that the repair process may slow down with time and the experimental data does not fit an exponential pattern. To address this enigma, we presented a generalized linea...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735058
更新日期:2012-06-01 00:00:00
abstract::Quantitative analysis of dynamic gadolinium-DTPA (diethylenetriamine pentaacetic acid) enhanced magnetic resonance imaging (MRI) is emerging as a highly sensitive tool for detecting malignant breast tissue. Three-dimensional rapid imaging techniques, such as keyhole MRI, yield high temporal sampling rates to accuratel...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598576
更新日期:1999-05-01 00:00:00
abstract:PURPOSE:Normal patient databases (NPDs) are used to distinguish between normal and abnormal perfusion in SPECT myocardial perfusion imaging (MPI) and have gained wide acceptance in the clinical environment, yet there are limitations to this approach. This study introduces a template-based method for semi-quantitative M...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3595112
更新日期:2011-07-01 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:PURPOSE:An original radionuclide calibrator method for activity determination is presented. The method could be used for intercomparison surveys for short half-life radioactive sources used in Nuclear Medicine, such as(99m)Tc or most positron emission tomography radiopharmaceuticals. METHODS:By evaluation of the resul...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4884035
更新日期:2014-07-01 00:00:00
abstract::A test device which can indirectly measure the performance of an automatic exposure control system and which offers the potential to reduce the time and film requirements for such tests has been evaluated. Evaluation results demonstrate that the device can successfully predict image optical density to within +/- 0.10 ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597252
更新日期:1994-01-01 00:00:00
abstract:PURPOSE:The purposes of this study is to measure the low frequency drop (LFD) of the modulation transfer function (MTF), associated with the long tails of the detector point spread function (PSF) of an on-board flat panel imager and study its impact on cone-beam CT (CBCT) image quality and scatter measurement accuracy....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4747260
更新日期:2012-09-01 00:00:00
abstract:PURPOSE:Scatter contamination in cone-beam computed tomography (CBCT) degrades the image quality by introducing shading artifacts. A moving-blocker-based approach has been proposed to simultaneously estimate scatter and reconstruct the complete volume within field of view (FOV) from a single CBCT scan. Promising result...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4811086
更新日期:2013-07-01 00:00:00
abstract::We have developed a new method for optimization in intensity modulated radiation therapy (IMRT) that makes use of simulated dynamics in a classical system of interacting particles. An analogy is drawn between intensity profile optimization in IMRT and relaxation to the equilibrium configuration in a dynamic system. Th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1528179
更新日期:2003-01-01 00:00:00
abstract::Contemporary reconstruction methods employed for clinical helical cone-beam computed tomography (CT) are analytical (noniterative) but mathematically nonexact, i.e., the reconstructed image contains so called cone-beam artifacts, especially for higher cone angles. Besides cone artifacts, these methods also suffer from...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2966353
更新日期:2008-09-01 00:00:00
abstract::In this x-ray/MR hybrid system an x-ray flat panel detector is placed under the patient cradle, close to the MR volume of interest (VOI), where the magnetic field strength is approximately 0.5 T. Immersed in this strong field, several electronic components inside the detector become magnetized and create an additional...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2963994
更新日期:2008-09-01 00:00:00
abstract::The polarity effect was investigated for three different commercially available plane-parallel ionization chambers: the Memorial Pipe chamber, the Victoreen/Nuclear Associates model 30-329 chamber manufactured by PTW, Frieburg, and the Capintec PS-033 thin-window ionization chamber. The primary study was the polarity ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596072
更新日期:1987-03-01 00:00:00
abstract::Many new models of 125I seeds are being introduced, mainly due to the increase in prostate seed implants. We have evaluated the SourceTech Medical (STM), model STM1251, 125I seed using thermoluminescent dosimeters (TLDs) in a solid water phantom. TLD cubes, LiF TLD-100, with dimension 1 mm on each edge, were irradiate...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1577251
更新日期:2003-07-01 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: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::The optimum x-ray spectra for acquisition of digital mammographic images using an amorphous selenium (a-Se) photoconductor are investigated. The recorded images consist of latent charge distributions on the surface of an a-Se plate, which are then read out using two methods, laser discharge, or flat panel recharge. Th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597688
更新日期:1996-04-01 00:00:00
abstract:PURPOSE:To determine the accuracy and test-retest repeatability of fast radiofrequency (RF) transmit measurement approaches used in Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI). Spatial variation in the transmitted RF field introduces bias and increased variance in quantitative DCE-MRI metrics includi...
journal_title:Medical physics
pub_type: 杂志文章,多中心研究
doi:10.1002/mp.13518
更新日期:2019-06-01 00:00:00
abstract::Patient-specific intensity-modulated radiotherapy (IMRT) verifications require an accurate two-dimensional dosimeter that is not labor-intensive. We assessed the precision and reproducibility of film calibrations over time, measured the elemental composition of the film, measured the intermittency effect, and measured...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1852791
更新日期:2005-02-01 00:00:00
abstract::Our purpose in this paper is to present an in vivo dosimetry program designed both for measuring the rectal dose and for avoiding misadministrations in gynecological intracavitary implants. A device containing an energy compensated diode was specially designed for these measurements. Our calibration procedure as well ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598598
更新日期:1999-05-01 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:To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. METHODS:Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4718680
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To investigate whether building a knowledge-based planning (KBP) model with prostate bed plans constructed from constrained hierarchical optimization (CHO) would result in more efficient model construction with more consistent output than a model built using plans from a traditional, trial-and-error-based optim...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13163
更新日期:2018-10-01 00:00:00
abstract:PURPOSE:Accurate segmentation of lungs with severe interstitial lung disease (ILD) in thoracic computed tomography (CT) is an important and difficult task in the development of computer-aided diagnosis (CAD) systems. Therefore, we developed in this study a texture analysis-based method for accurate segmentation of lung...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3222872
更新日期:2009-10-01 00:00:00
abstract::This paper deals with methods of reducing the total time required to acquire the projection data for a set of contiguous computed tomography (CT) images. Normally during the acquisition of a set of slices, the patient is held stationary during data collection and translated to the next axial location during an intersc...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596464
更新日期:1990-11-01 00:00:00