Photon attenuation in computed tomography.

abstract：:The minimum margins required to compensate for random geometric uncertainties in the delivery of radiotherapy treatment were determined for a spherical Clinical Target Volume, using an analytic model for the cumulative dose. Margins were calculated such that the minimum dose in the target would be no less than 95% of ...

journal_title：Medical physics

authors： Witte MG,van der Geer J,Schneider C,Lebesque JV,van Herk M

更新日期：2004-11-01 00:00:00

abstract：:In this work, we present a calcification-detection scheme that automatically localizes calcifications in a previously detected cluster in order to generate the input for a cluster-classification scheme developed in the past. The calcification-detection scheme makes use of three pieces of a priori information: the loca...

journal_title：Medical physics

authors： Salfity MF,Nishikawa RM,Jiang Y,Papaioannou J

更新日期：2003-05-01 00:00:00

abstract：PURPOSE:One of the promising options for motion management in radiation therapy (RT) is the use of LINAC-compatible robotic-arm-mounted ultrasound imaging system due to its high soft tissue contrast, real-time capability, absence of ionizing radiation, and low cost. The purpose of this work is to develop a novel deep l...

journal_title：Medical physics

authors： Huang P,Yu G,Lu H,Liu D,Xing L,Yin Y,Kovalchuk N,Xing L,Li D

更新日期：2019-05-01 00:00:00

abstract：:An applicator system for intraoperative radiation therapy has been fabricated which does not require physical docking with the accelerator. A dosimetric study has been completed which documents the properties of this system for a variety of electron beam energies, applicator sizes, collimator settings, both primary an...

journal_title：Medical physics

authors： Nelson CE,Cook R,Rakfal S

更新日期：1989-09-01 00:00:00

abstract：:A double-mirror multilayer monochromator was developed for the purpose of irradiating live cell cultures at the Synchrotron Radiation Center, University of Wisconsin-Madison. The monochromator is designed for the soft x-ray region with photon energies between 270 and 2400 eV. Multilayer mirrors with 55 bilayers of W/C...

journal_title：Medical physics

authors： MacKay JF,Pearson DW,Nelms BE,DeLuca PM Jr,Gould MN,Lagally MG

更新日期：1998-05-01 00:00:00

abstract：PURPOSE:To develop an automated technique for evaluating lung stereotactic body radiotherapy (SBRT) plan quality and predicting achievable lung dose constraints. METHODS:We examined the workflow scripting capabilities of a radiation oncology software package (MIM Software Inc) for automatically generating mean dose gr...

journal_title：Medical physics

authors： Atwood T,Xing L,Hristov D

更新日期：2012-06-01 00:00:00

abstract：:In a series of in vivo experiments on five adult canines, a small cylindrical permanent magnet (approximately 5-mm diameter x 5 mm long) was magnetically moved under fluoroscopic guidance from an occipital-lobe burr hole to a predetermined destination within the brain and then removed. On three of the animals, dorsal ...

journal_title：Medical physics

authors： Grady MS,Howard MA 3rd,Molloy JA,Ritter RC,Quate EG,Gillies GT

更新日期：1990-05-01 00:00:00

abstract：:The hybrid algorithms developed recently for the reconstruction of fan-beam images possess computational and noise properties superior to those of the fan-beam filtered backprojection (FFBP) algorithm. However, the hybrid algorithms cannot be applied directly to a halfscan fan-beam sinogram because they require knowle...

journal_title：Medical physics

authors： Pan X

更新日期：2000-09-01 00:00:00

abstract：:This study evaluates the effects of respiratory motion on breast radiotherapy delivered using segmented multileaf collimator (SMLC) intensity modulation. An anthropomorphic breast phantom was constructed of polystyrene plates between which radiographic films were inserted. The phantom was mounted on a moving platform ...

journal_title：Medical physics

authors： Liu Q,McDermott P,Burmeister J

更新日期：2007-01-01 00:00:00

abstract：PURPOSE:Cone beam computed tomography (CBCT) suffers from a large amount of scatter, resulting in severe scatter artifacts in the reconstructions. Recently, a new scatter correction approach, called improved primary modulator scatter estimation (iPMSE), was introduced. That approach utilizes a primary modulator that is...

journal_title：Medical physics

authors： Bier B,Berger M,Maier A,Kachelrieß M,Ritschl L,Müller K,Choi JH,Fahrig R

更新日期：2017-09-01 00:00:00

abstract：:In a recent paper of Miller et al. (Med. Phys. 43(5), 2141-2152 (2016), the voltage dependence polarity effect of microionization chambers was studied. It was identified that polarity effect arises from the difference in electric potential between the collecting electrode and the guard electrode, which in turn deforms...

journal_title：Medical physics

authors： Brivio D,Sajo E,Zygmanski P

更新日期：2017-03-01 00:00:00

abstract：PURPOSE:The Imaging and Radiation Oncology Core Houston (IROC-H) (formerly the Radiological Physics Center) has reported varying levels of agreement in their anthropomorphic phantom audits. There is reason to believe one source of error in this observed disagreement is the accuracy of the dose calculation algorithms an...

journal_title：Medical physics

authors： Faught AM,Davidson SE,Fontenot J,Kry SF,Etzel C,Ibbott GS,Followill DS

更新日期：2017-09-01 00:00:00

abstract：PURPOSE:The segmentation accuracy of medical images was improved by increasing the number of training samples using a local image warping technique. The performance of the proposed method was evaluated in the segmentation of breast masses, prostate and brain tumors, and lung nodules. METHODS:We propose a simple data a...

journal_title：Medical physics

authors： Liu H,Cao H,Song E,Ma G,Xu X,Jin R,Liu T,Liu L,Liu D,Hung CC

更新日期：2020-12-10 00:00:00

abstract：:A water beam imaging system (WBIS) has been developed and used to verify dose distributions for intensity modulated radiotherapy using dynamic multileaf collimator. This system consisted of a water container, a scintillator screen, a charge-coupled device camera, and a portable personal computer. The scintillation ima...

journal_title：Medical physics

authors： Li JS,Boyer AL,Ma CM

更新日期：2001-12-01 00:00:00

abstract：PURPOSE:The purpose of this study was to describe and evaluate methods for calculating a megavoltage computed tomography (MVCT)-derived MR hardware attenuation map (μ-map) and dual-energy CT (DECT) for 511 keV photons. METHODS:Phantom measurements were acquired on a whole-body hybrid PET/MRI system, using a four-chann...

journal_title：Medical physics

authors： Patrick JC,Terry Thompson R,So A,Butler J,Faul D,Stodilka RZ,Yartsev S,Prato FS,Gaede S

更新日期：2017-09-01 00:00:00

abstract：:A filtered backprojection algorithm is developed for single photon emission computed tomography (SPECT) imaging with an astigmatic collimator having a displaced center of rotation. The astigmatic collimator has two perpendicular focal lines, one that is parallel to the axis of rotation of the gamma camera and one that...

journal_title：Medical physics

authors： Wang H,Smith MF,Stone CD,Jaszczak RJ

更新日期：1998-08-01 00:00:00

abstract：:An algorithmic solution to the biological effective dose (BED) calculation from the Lea-Catcheside formula for a piecewise defined function is presented. Data from patients treated for metastatic thyroid cancer were used to illustrate the solution. The Lea-Catcheside formula for the G-factor of the BED is integrated n...

journal_title：Medical physics

authors： Hobbs RF,Sgouros G

更新日期：2009-03-01 00:00:00

abstract：PURPOSE:To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy (including cone beam CT verification) following breast conservation surgery for early breast cancer. METHOD:Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermo...

journal_title：Medical physics

authors： Donovan EM,James H,Bonora M,Yarnold JR,Evans PM

更新日期：2012-10-01 00:00:00

abstract：:Stereo x-ray radiography attracts increasing attention in major clinical applications. The purpose of this paper is to analyze the 3D localization error for breast biopsy procedures and provide guidelines for improving its accuracy. Our prototype is a CCD based digital stereo x-ray imaging system. The mathematical mod...

journal_title：Medical physics

authors： Jiang H,Liu H,Wang G,Chen W,Fajardo LL

更新日期：2000-05-01 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

authors： Chen Y,Chiu B

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:Patient motion is a common problem during dynamic positron emission tomography (PET) scans for quantification of myocardial blood flow (MBF). The purpose of this study was to quantify the prevalence of body motion in a clinical setting and evaluate with realistic phantoms the effects of motion on blood flow qua...

journal_title：Medical physics

authors： Hunter CR,Klein R,Beanlands RS,deKemp RA

更新日期：2016-04-01 00:00:00

abstract：:Energy imparted is a measure of the total ionizing energy deposited in the patient during a radiologic examination and may be used to quantify the patient dose in diagnostic radiology. Values of the energy imparted per unit exposure-area product, omega (z), absorbed by a semi-infinite water phantom with a thickness z,...

journal_title：Medical physics

authors： Gkanatsios NA,Huda W

更新日期：1997-04-01 00:00:00

abstract：:Hyperthermia, as an adjuvant with radiation and chemotherapy, has shown promise in the treatment of cancer. The relevant biological effects of a hyperthermia treatment are both time and temperature-dependent, creating a need for accurate thermometry. We present a novel noninvasive thermometry modality that combines a ...

journal_title：Medical physics

authors： Dreher MR,Elas M,Ichikawa K,Barth ED,Chilkoti A,Rosen GM,Halpern HJ,Dewhirst M

更新日期：2004-10-01 00:00:00

abstract：PURPOSE:The thermoluminescence dosimeter (TLD) has desirable features including low cost, reusability, small size, and relatively low energy dependence. However, the commonly available poly-crystal TLDs (e.g., TLD-100) exhibit high interdetector variability that requires individual calibration for high detection accura...

journal_title：Medical physics

authors： Shang D,Gu W,Landers A,Woods K,Yu V,Neph R,Tenn S,Sheng K

更新日期：2020-01-01 00:00:00

abstract：PURPOSE:The authors describe the integration of optical imaging with a targeted small animal irradiator device, focusing on design, instrumentation, 2D to 3D image registration, 2D targeting, and the accuracy of recovering and mapping the optical signal to a 3D surface generated from the cone-beam computed tomography (...

journal_title：Medical physics

authors： Weersink RA,Ansell S,Wang A,Wilson G,Shah D,Lindsay PE,Jaffray DA

更新日期：2014-10-01 00:00:00

abstract：:This paper investigates the effect of the waterproofing sleeve on the calibration of kilovoltage photon beams (50-300 kV). The sleeve effect correction factor, ps has been calculated using the Monte Carlo method as the ratios of the air kerma in an air cavity of a cylindrical chamber without the waterproofing sleeve t...

journal_title：Medical physics

authors： Ma CM,Seuntjens JP

更新日期：1997-09-01 00:00:00

abstract：:Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S val...

journal_title：Medical physics

authors： Pacilio M,Lanconelli N,Lo MS,Betti M,Montani L,Torres AL,Coca PM

更新日期：2009-05-01 00:00:00

abstract：PURPOSE:The most common material for shielding is concrete, which can be made using various materials of different densities as aggregates. New techniques in radiotherapy, as IMRT and VMAT, require more monitor units and it is important to develop specifically designed shielding materials. METHODS:Arraela S.L. has dev...

journal_title：Medical physics

authors： Mera M,Pereira L,Mera M,Pereira L,Meilán E,Moral FD,Teijeiro A,Salgado M,Andrade B,Gomez F,Fuentes-Vázquez V,Caruncho J,Medina A

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Stray neutron radiation is of concern after radiation therapy, especially in children, because of the high risk it might carry for secondary cancers. Several previous studies predicted the stray neutron exposure from proton therapy, mostly using Monte Carlo simulations. Promising attempts to develop analytical ...

journal_title：Medical physics

authors： Pérez-Andújar A,Zhang R,Newhauser W

更新日期：2013-12-01 00:00:00

abstract：:Estimated photon energy spectra are derived from transmission measurements using aluminium, copper, and sodium iodide absorbers. Two spectral models are proposed. One is based on a previously published model that analyzes the electron's penetration into the anode, and the production and attenuation of bremsstrahlung p...

journal_title：Medical physics

authors： Ruth C,Joseph PM

更新日期：1997-05-01 00:00:00