Abstract：
:The purpose of this study is to develop a 4D inverse planning strategy capable of controlling the appearance of the implanted fiducial(s) in segmented IMRT fields for cine MV or combined MV/kV image-guided IMRT. This work is focused on enhancing the visibility of the implanted fiducial(s) in 4D IMRT inverse planning, whose goal is to derive a set of time-resolved (or phase-tagged) MLC segments to cater for the motion of the patient anatomy extracted from the emerging 4D images. The task is to optimize the shapes and weights of all the segments for each incident beam, with the fiducial(s) being forced/encouraged to be inside the segmented fields. The system is modeled by a quadratic objective function with inclusion of a hard/soft constraint characterizing the authors' level of preference for the fiducial(s) to be included in the segmented fields. A simulated annealing algorithm is employed to optimize the system. The proposed technique is demonstrated using two clinical cases. A segment-based inverse planning framework for 4D radiation therapy, capable of providing tempospatially optimized IMRT plans, has been established. Furthermore, using the described 4D optimization approach, it is demonstrated that the MLC blockage of the implanted fiducial(s) during the segmented delivery is avoided without severely compromising the final dose distribution. The visibility of implanted fiducials in 4D IMRT can be improved without significantly deteriorating final dose distribution. This is a foundation for the authors to use cine MV or combined MV/KV to effectively guide the 4D IMRT delivery.
journal_name
Med Physjournal_title
Medical physicsauthors
Ma Y,Lee L,Keshet O,Keall P,Xing Ldoi
10.1118/1.3121425subject
Has Abstractpub_date
2009-06-01 00:00:00pages
2215-21issue
6eissn
0094-2405issn
2473-4209journal_volume
36pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:The ionizing radiation imparted to patients during computed tomography exams is raising concerns. This paper studies the performance of a scheme called dose reduction using prior image constrained compressed sensing (DR-PICCS). The purpose of this study is to characterize the effects of a statistical model of x...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4773866
更新日期：2013-02-01 00:00:00
abstract：PURPOSE:To investigate tight-frame based iterative reconstruction (TFIR) technique for spectral breast computed tomography (CT) using fewer projections while achieving greater image quality. METHODS:The experimental data were acquired with a fan-beam breast CT system based on a cadmium zinc telluride photon-counting d...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4790468
更新日期：2013-03-01 00:00:00
abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4754797
更新日期：2012-10-01 00:00:00
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...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2965975
更新日期：2008-07-01 00:00:00
abstract：PURPOSE:To compare the estimate of normalized glandular dose in mammography and breast CT imaging obtained using the actual glandular tissue distribution in the breast to that obtained using the homogeneous tissue mixture approximation. METHODS:Twenty volumetric images of patient breasts were acquired with a dedicated...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4737025
更新日期：2012-08-01 00:00:00
abstract：:Cardiac arrhythmias are a major health burden, associated with reduced quality of life and substantial morbidity and mortality. Current therapy includes moderately effective medication and catheter-based ablation of arrhythmogenic substrates in the heart. Catheter interventions frequently have to be repeated due to re...
journal_title：Medical physics
pub_type： 杂志文章,评审
doi：10.1002/mp.12595
更新日期：2018-11-01 00:00:00
abstract：PURPOSE:The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI). METHODS:Time-sequenced b-mode...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13104
更新日期：2018-10-01 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:In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR (192)Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambe...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4816673
更新日期：2013-09-01 00:00:00
abstract：:In this article, we report on the development of a simple and accurate method for quality assurance of electron beam output and energy. Aluminum disks of thicknesses d(max) or d50 of the particular electron energy are positioned sequentially over a parallel-plate ion chamber and the ratio of the two signals is compare...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1688040
更新日期：2004-05-01 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:Recent guidance by The Joint Commission and CRCPD recommendations require establishing CT reference dose levels (RDLs) for clinical protocols and recording CT dose metrics in the patient's medical record. This presentation addresses which dose values in the CT report should be recorded for the purposes of monit...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734773
更新日期：2012-06-01 00:00:00
abstract：:The relative sensitivity of the half-value layer (HVL) method as a quality index for megavoltage x-ray beams is examined by theoretical calculation and experimental measurements for 4-, 6-, 10-, and 25-MV x-ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595794
更新日期：1985-01-01 00:00:00
abstract：:A multislit collimator was designed and fabricated for basic studies on microbeam radiation therapy (MRT) with an x-ray energy of about 100 keV. It consists of 30 slits that are 25 microm high, 30 mm wide, and 5 mm thick in the beam direction. The slits were made of 25 microm-thick polyimide sheets that were separated...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2940157
更新日期：2008-07-01 00:00:00
abstract：PURPOSE:In fractionated radiation therapy, image guidance with daily tomographic imaging becomes more and more clinical routine. In principle, this allows for daily computation of the delivered dose and for accumulation of these daily dose distributions to determine the actually delivered total dose to the patient. How...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3697524
更新日期：2012-04-01 00:00:00
abstract：PURPOSE:Automated segmentation of brain structures (objects) in MR three-dimensional (3D) images for quantitative analysis has been a challenge and probabilistic atlases (PAs) are among the most well-succeeded approaches. However, the existing models do not adapt to possible object anomalies due to the presence of a di...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13771
更新日期：2019-11-01 00:00:00
abstract：:Testing computer-controlled linear accelerators for patient safety and proper patient dose delivery requires that certain beam characteristics be monitored over an extended period of time. Computer-controlled conformal radiation therapy using asymmetric collimator jaw settings necessitates stable symmetric treatment b...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596363
更新日期：1989-07-01 00:00:00
abstract：:Anisotropy of dose distributions around 103Pd, 125I, and 192Ir sources for interstitial brachytherapy was examined. Dose rates around 125I models 6702 and 6711 and 192Ir sources were measured using lithium fluoride thermoluminescence dosimeters (LiF TLDs) in a water-equivalent, solid phantom. From these measured data ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597110
更新日期：1993-09-01 00:00:00
abstract：:The goal of this study was to develop a technique to distinguish benign and malignant breast lesions in secondarily digitized mammograms. A set of 51 mammograms (two views/patient) containing lesions of known pathology were evaluated using six different morphological descriptors: circularity, mu R/sigma R (where mu R ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597707
更新日期：1996-08-01 00:00:00
abstract：:The proper evaluation of the accuracy of a new computer program for radiation-therapy dosimetry requires consideration of both the mathematical algorithm used in the program and the performance required in clinical applications. As an example, our evaluation of the irregular-fields dosimetry program currently marketed...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594344
更新日期：1977-11-01 00:00:00
abstract：:In the case of non-small cell lung cancer, doses typically prescribed (60-66 Gy) are not sufficient to ensure a satisfactory tumor control probability. Dose escalation needs to be realized, but dose to organs at risk (OARs) must be kept under widely accepted clinical thresholds. Also, lung functionality is not homogen...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2965976
更新日期：2008-07-01 00:00:00
abstract：:A Monte Carlo study of dosimetry for eye plaque brachytherapy is performed. BrachyDose, an EGSnrc user code which makes use of Yegin's multi-geometry package, is used to fully model I125 (model 6711) and Pd103 (model 200) brachytherapy seeds and the standardized plaques of the Collaborative Ocular Melanoma Study (COMS...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3002412
更新日期：2008-12-01 00:00:00
abstract：:The gamma-ray dose component of a d(80) + Be neutron beam was measured with a 6Li-shielded Geiger-Mueller counter in a tissue-equivalent liquid phantom. The proportion of gamma-ray dose to total dose increased from 0.07 near the surface to 0.09 at 25 cm depth. Due to thermal neutron sensitivity, the G-M count rate inc...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594571
更新日期：1979-05-01 00:00:00
abstract：:Spectra, yields, average energies, and kerma rates in tissue of neutrons from 21-MeV deuteron bombardment of deuterium gas targets have been calculated for target thicknesses of 1, 3.5, and 5 MeV. A high pressure gas cell was constructed and was filled with 33 atm of D2 gas (equivalent to an energy loss of 3.5 MeV for...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594561
更新日期：1979-05-01 00:00:00
abstract：OBJECTIVES:To evaluate the performance of RapidArc® (Eclipse 10.0.28) and SmartArc® (Pinnacle 9.0) radiotherapy plans for lung stereotactic body radiation therapy (SBRT) in terms of dosimetric plan quality, delivery efficiency, inhomogeneity corrections and accuracy of dose delivery using a custom-built heterogeneity i...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4740172
更新日期：2012-07-01 00:00:00
abstract：PURPOSE:The purpose of this work was to examine the suitability of VIPARnd polymer gel-9.4 T magnetic resonance microimaging system for high spatial resolution dose distribution measurements. METHODS:The VIPARnd samples (3 cm in outside diameter and 12 cm in height) were exposed to ionizing radiation by using a linear...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14186
更新日期：2020-08-01 00:00:00
abstract：:New radiation therapy techniques such as IMRT present significant efficiency due to their highly conformal dose distributions. A consequence of the complexity of their dose distributions (high gradients, small irradiation fields, low dose distribution, ...) is the requirement for better precision quality assurance tha...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2897966
更新日期：2008-05-01 00:00:00
abstract：PURPOSE:Two types of tumor hypoxia most likely exist in human cancers: Chronic hypoxia due to the paucity of blood capillaries and acute hypoxia due to temporary shutdoWn of microvasculatures or fluctuation in the red cell flux. In a recent hypoxia imaging study using 18F-FMISO PET, the authors observed variation in tr...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3213092
更新日期：2009-10-01 00:00:00
abstract：PURPOSE:The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4939663
更新日期：2016-02-01 00:00:00
abstract：:Weighting of given doses from parallel opposed fields is a widespread practice in radiation therapy of cancer in the tonsillar region. In order to determine when weighting is useful, dose distributions on the central axis were calculated for various energies (60Co, 4-, 8-, 15-, and MVp photons), weighting factors, and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594276
更新日期：1976-03-01 00:00:00
