Abstract:
PURPOSE:To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. METHODS:Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patients were treated with conventional fractionation using an IMRT dose painting technique, most with 33 fractions. Weekly radiographic imaging was used to correct the patient setup. The authors used rigid registration of the planning CT and Cone Beam CT scans to find the translational and rotational setup errors, and the spatial setup errors of the cochlea. The planning CT was rotated and translated such that the cochlea positions match those seen in the cone beam scans, cochlea doses were recalculated and fractional doses accumulated. Uncertainties in the positions and cumulative doses of the cochlea were calculated with and without setup adjustments from radiographic imaging. RESULTS:The mean setup error of the cochlea was 0.04 ± 0.33 or 0.06 ± 0.43 cm for RL, 0.09 ± 0.27 or 0.07 ± 0.48 cm for AP, and 0.00 ± 0.21 or -0.24 ± 0.45 cm for SI with and without radiographic imaging, respectively. Setup with radiographic imaging reduced the standard deviation of the setup error by roughly 1-2 mm. The uncertainty of the cochlea dose depends on the treatment plan and the relative positions of the cochlea and target volumes. Combining results for the left and right cochlea, the authors found the accumulated uncertainty of the cochlea dose per fraction was 4.82 (0.39-16.8) cGy, or 10.1 (0.8-32.4) cGy, with and without radiographic imaging, respectively; the percentage uncertainties relative to the planned doses were 4.32% (0.28%-9.06%) and 10.2% (0.7%-63.6%), respectively. CONCLUSIONS:Patient setup error introduces uncertainty in the position of the cochlea during radiation treatment. With the assistance of radiographic imaging during setup, the standard deviation of setup error reduced by 31%, 42%, and 54% in RL, AP, and SI direction, respectively, and consequently, the uncertainty of the mean dose to cochlea reduced more than 50%. The authors estimate that the effects of these uncertainties on the probability of hearing loss for an individual patient could be as large as 10%.
journal_name
Med Physjournal_title
Medical physicsauthors
Yan M,Lovelock D,Hunt M,Mechalakos J,Hu Y,Pham H,Jackson Adoi
10.1118/1.4830427subject
Has Abstractpub_date
2013-12-01 00:00:00pages
121724issue
12eissn
0094-2405issn
2473-4209journal_volume
40pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. METHODS:To study...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12899
更新日期:2018-06-01 00:00:00
abstract::The determination of the radiation exposure history of the population has become increasingly important in the study of the effects of low-level radiation. The present work was started to try to obtain an in vivo dosimeter that could give an indication of radiation exposure. Dental enamel is the only living tissue whi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595768
更新日期:1985-05-01 00:00:00
abstract:PURPOSE:To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on sev...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3598441
更新日期:2011-07-01 00:00:00
abstract:PURPOSE:To evaluate dependence of measured dose on size and location of region of interest (ROI) in Gafchromic EBT3 film dosimetry. METHODS:Gafchromic EBT3 films were irradiated perpendicularly using the 6MV beam from a linear accelerator at 10 cm depth (100 cm SSD) of a 30 × 30 × 20 cm3 solid water phantom for a rang...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12885
更新日期:2018-05-01 00:00:00
abstract:PURPOSE:Cone-beam CT (CBCT) images contain severe shading artifacts mostly due to scatter. Many algorithms have been proposed to alleviate this problem by data correction on projections. Sophisticated methods have also been designed to further improve the image quality when prior patient information is available. In th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736218
更新日期:2012-06-01 00:00:00
abstract::A detailed derivation is presented of the formulas required to determine Ngas and Dmed in the AAPM TG-21 dosimetry protocol. This protocol specifies how to determine the absorbed dose in an electron or photon beam when using exposure or absorbed dose calibrated ion chambers. It is shown that the expression given in TG...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596292
更新日期:1988-01-01 00:00:00
abstract::Optimal visualization of moving structures such as the heart and coronary arteries using digital radiographic imaging systems is a difficult problem that can involve tradeoffs between temporal, spatial, and density resolution. The motion dependence of four angiographic measures of vessel dimensions is given and demons...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595651
更新日期:1985-11-01 00:00:00
abstract:PURPOSE:Atherosclerosis of peripheral cerebral arteries can lead to stroke either by stenosis formation or plaque rupture. This pathology is initiated by the alteration of arterial wall mechanical properties shown to be assessable by ultrasound elastography. Recently, noninvasive vascular elastography (NIVE) was introd...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3539701
更新日期:2011-02-01 00:00:00
abstract:PURPOSE:To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. METHODS:In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4719962
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Modern CT systems adjust X-ray flux accommodating for patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. The objective of this study was to characterize CT per...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12172
更新日期:2017-06-01 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:To apply the dual ionization chamber method for mixed radiation fields to an accurate comparison of the secondary neutron dose arising from the use of a tungsten alloy multileaf collimator (MLC) as opposed to a brass collimator system for defining the shape of a therapeutic proton field. METHODS:Hydrogenous an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3656025
更新日期:2011-11-01 00:00:00
abstract:PURPOSE:We report on the development of the open-source cross-platform radiation treatment planning toolkit matRad and its comparison against validated treatment planning systems. The toolkit enables three-dimensional intensity-modulated radiation therapy treatment planning for photons, scanned protons and scanned carb...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12251
更新日期:2017-06-01 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::Neutron energy spectra and spectra of dose deposition in tissue-equivalent material have been measured for neutron sources produced by 16-, 22-, 35-, and 45.5-MeV deuterons and 22.5-, 35-, 45-, and 65.5-MeV protons incident upon a thick beryllium target. Neutron spectra were measured using time-of-flight techniques an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594392
更新日期:1977-05-01 00:00:00
abstract::Simultaneous rest 99mTc-Sestamibi/ 123I-BMIPP cardiac SPECT imaging has the potential to replace current clinical 99mTc-Sestamibi rest/stress imaging and therefore has great potential in the case of patients with chest pain presenting to the emergency department. Separation of images of these two radionuclides is diff...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3063544
更新日期:2009-02-01 00:00:00
abstract:PURPOSE:To evaluate the energy dependence of Gafchromic EBT3 film for establishing a quality assurance method of bolus electron conformal radiotherapy. METHODS:We irradiated electron beam to EBT3 films, which were set in the water tank. The linear accelerator used was Varian Clinac 21EX. The energy of electron beams w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735200
更新日期:2012-06-01 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:PURPOSE:To show that Cherenkov emission is generated by external radiotherapy beam in tissue, and could serve as optical source to excite an oxygen sensitive phosphor, Oxyphor G4, within tissue. The intensity and lifetime of the phosphorescence was measured with a time-gated system and reveals the oxygenation levels in...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734811
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4941954
更新日期:2016-03-01 00:00:00
abstract:PURPOSE:The quality of tomographic images is directly affected by the system model being used in image reconstruction. An accurate system matrix is desirable for high-resolution image reconstruction, but it often leads to high computation cost. In this work the authors present a maximum a posteriori reconstruction algo...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3284980
更新日期:2010-02-01 00:00:00
abstract::With the increased sophistication of lasers used for patient positioning in radiotherapy comes increased possibilities for mistakes in installing the lasers, which can result in serious patient positioning errors. Two principles must be followed when mounting cross-projecting lasers: (1) the horizontal line must be on...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594960
更新日期:1981-05-01 00:00:00
abstract::Some limitations of conventional two-dimensional computer programs used to plan radiation therapy are presented. These include: a lack of involvement in defining the clinical problem; deficiencies in the algorithms for computing dose; failure to compute dose throughout the volume of interest; an inability to handle tr...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595226
更新日期:1982-07-01 00:00:00
abstract::The widespread application of positron emission tomography (PET) in clinical oncology has driven this imaging technology into a number of new research and clinical arenas. Increasing numbers of patient scans have led to an urgent need for efficient data handling and the development of new image analysis techniques to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2432404
更新日期:2007-02-01 00:00:00
abstract::We propose the use of conic and cubic surface equations (surfaces of second and third order) to directly approximate the dual-energy equations (the integral equations for the dual-energy log-signal functions, i.e., the negative logarithms of the relative detector signals, considered as functions of the basis-material ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596512
更新日期:1990-05-01 00:00:00
abstract:PURPOSE:Distortions in magnetic resonance imaging (MRI) compromise spatial fidelity, potentially impacting delineation and dose calculation. We characterized 2D and 3D large field of view (FOV), sequence-independent distortion at various positions in a 1.0 T high-field open MR simulator (MR-SIM) to implement correction...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4930245
更新日期:2015-10-01 00:00:00
abstract:PURPOSE:Repeated brain MRI scans are performed in many clinical scenarios, such as follow up of patients with tumors and therapy response assessment. In this paper, the authors show an approach to utilize former scans of the patient for the acceleration of repeated MRI scans. METHODS:The proposed approach utilizes the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4928148
更新日期:2015-09-01 00:00:00
abstract::Calibration of an imported strontium-90 ophthalmic applicator at the U.S. National Bureau of Standards (now the National Institute of Standards and Technology) has disclose a significant discrepancy in dose rate calibration (32%-35%) with that quoted by the manufacturer. The University of Wisconsin has investigated th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596702
更新日期:1991-03-01 00:00:00
abstract:PURPOSE:The previously described 2D standardized vessel-wall-plus-plaque thickness (VWT) maps constructed from 3D ultrasound vessel wall measurements using an arc-length (AL) scaling approach adjusted the geometric variability of carotid arteries and has allowed for the comparisons of VWT distributions in longitudinal ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4966702
更新日期:2016-12-01 00:00:00
abstract:PURPOSE:Precise segmentation of clinical target volume (CTV) is the key to stomach cancer radiotherapy. We proposed a novel stochastic width - deep neural network (SW-DNN) for better automatically contouring stomach CTV METHODS: SW-DNN was an end-to-end approach, of which the core component was a novel SW mechanism tha...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14733
更新日期:2021-01-27 00:00:00