MR acoustic radiation force imaging: in vivo comparison to ultrasound motion tracking.

abstract：PURPOSE:Dynamic myocardial perfusion computed tomography (DM-PCT) imaging offers benefits over quantitative assessment of myocardial blood flow (MBF) for diagnosis and risk stratification of coronary artery disease. However, one major drawback of DM-PCT imaging is that a high radiation level is imparted by repeated sca...

journal_title：Medical physics

authors： Bian Z,Zeng D,Zhang Z,Gong C,Tian X,Yan G,Huang J,Guo H,Chen B,Zhang J,Feng Q,Chen W,Ma J

更新日期：2017-09-01 00:00:00

abstract：:The radiation dose to the lungs from 133Xe in lung air is directly proportional to the time integral of 133Xe concentration; i.e., the cumulated concentration in the lungs. Using kinetic models developed to fit clinical observations, we have studied the effect of retention on cumulated concentration in lung air. The m...

journal_title：Medical physics

authors： Watson EE,Cloutier RJ

更新日期：1977-11-01 00:00:00

abstract：:As a potentially important technology for medical x-ray computed tomography (CT), lambda tomography (LT) is to reconstruct a gradient-like image only from local projection data. Based on our recently derived exact fan-beam LT formula, [H. Y. Gu and G. Wang, Int. J. Biomed. Imaging 2006(1), 1-9 (2006)] here we propose ...

journal_title：Medical physics

authors： Yu H,Ye Y,Wang G

更新日期：2006-10-01 00:00:00

abstract：:The anti-scatter grid has been widely used to reject scatter and increase the perceptibility of a low-contrast object in chest radiography; however, it also attenuated the primary x-rays, resulting in a substantial loss of information and an increased relative noise level in heavily attenuated regions. A more dose eff...

journal_title：Medical physics

authors： Liu X,Shaw CC

更新日期：2007-07-01 00:00:00

abstract：:Estimates of the effective dose to adult patients from computed tomography (CT) head scanning can be calculated using a number of different methods. These estimates can be used for a variety of purposes, such as improving scanning protocols, comparing different CT imaging centers, and weighing the benefits of the scan...

journal_title：Medical physics

authors： Gregory KJ,Bibbo G,Pattison JE

更新日期：2008-08-01 00:00:00

abstract：:Calcium concentration may be a useful feature for distinguishing benign from malignant lung nodules in computer-aided diagnosis. The calcium concentration can be estimated from the measured CT number of the nodule and a CT number vs calcium concentration calibration line that is derived from CT scans of two or more ca...

journal_title：Medical physics

authors： Goodsitt MM,Chan HP,Way TW,Schipper MJ,Larson SC,Christodoulou EG

更新日期：2009-07-01 00:00:00

abstract：:Pixel size is of great interest in the flat-panel detector design because of its potential impact on image quality. In the particular case of angiographic x-ray fluoroscopy, small pixels are required in order to adequately visualize interventional devices such as guidewires and stents which have wire diameters as smal...

journal_title：Medical physics

authors： Jiang Y,Wilson DL

更新日期：2006-03-01 00:00:00

abstract：:We have studied the effect of real-time optical image processing (OIP) in an image intensifier/television (II-TV) radiographic imaging system by using a liquid-crystal display (LCD) placed between the II and the TV camera. The LCD compresses the dynamic range of the transmitted image by modulating the spatial distribu...

journal_title：Medical physics

authors： Lam KL,Chan HP,Doi K

更新日期：1988-11-01 00:00:00

abstract：:While simple, intravascular brachytherapy (IVB) presents a considerable potential for harm to the patient. The medical physicist maintains the responsibility to minimize the likelihood of operational problems or dosimetric errors. The principals for safe operation remain the same as with any radiotherapy treatment: to...

journal_title：Medical physics

authors： Chakri A,Thomadsen B

更新日期：2002-12-01 00:00:00

abstract：PURPOSE:For the past two decades, high-Z nanoparticles have been of high interest to improve the therapeutic outcomes of radiation therapy, especially for low-energy X-rays. Monte Carlo (MC) simulations have been used to evaluate the boost of dose deposition induced by Auger electrons near the nanoparticle surface, by ...

journal_title：Medical physics

authors： Poignant F,Monini C,Testa É,Beuve M

更新日期：2020-11-04 00:00:00

abstract：:Linac calibration is done in water, but patients are comprised primarily of soft tissue. Conceptually, and specified in NRG/RTOG trials, dose should be reported as dose-to-muscle to describe the dose to the patient. Historically, the dose-to-water of the linac calibration was often converted to dose-to-muscle for pati...

journal_title：Medical physics

authors： Kry SF,Feygelman V,Balter P,Knöös T,Charlie Ma CM,Snyder M,Tonner B,Vassiliev ON

更新日期：2020-03-01 00:00:00

abstract：:One of the methods currently being used to treat choroidal melanoma employs an episcleral plaque containing I-125 radioactive seeds. However, comprehensive dosimetry studies on the plaque are scarce and controversial. For this work, we use film to study the dosimetry outside the lip of the gold shield of the eye plaqu...

journal_title：Medical physics

authors： Wu A,Krasin F

更新日期：1990-09-01 00:00:00

abstract：:In this study we address the problem of predicting the position of a moving lung tumor during respiration on the basis of external breathing signals--a technique used for beam gating, tracking, and other dynamic motion management techniques in radiation therapy. We demonstrate the use of neural network filters to corr...

journal_title：Medical physics

authors： Isaksson M,Jalden J,Murphy MJ

更新日期：2005-12-01 00:00:00

abstract：:Permanent implants of 125I seeds at Memorial Sloan-Kettering Cancer Center are performed by the method of "dimension averaging" to determine the total activity to be implanted; that is, the activity (in mCi) is taken to be five times the average dimension (in cm) of the target region. A nomograph has recently been dev...

journal_title：Medical physics

authors： Anderson LL

更新日期：1976-01-01 00:00:00

abstract：PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

journal_title：Medical physics

authors： Li T,Li X,Yang Y,Heron DE,Huq MS

更新日期：2010-12-01 00:00:00

abstract：PURPOSE:The aim of this study was to demonstrate a new model for implementing a transit dosimetry system as a means of in vivo dose verification with a water equivalent electronic portal imaging device (WE-EPID) and a conventional treatment planning system (TPS). METHOD AND MATERIALS:A standard amorphous silicon (a-Si...

journal_title：Medical physics

authors： Deshpande S,Blake SJ,Xing A,Metcalfe PE,Holloway LC,Vial P

更新日期：2018-03-01 00:00:00

abstract：PURPOSE:To study the relationships between dose (D), kerma (K), and collision kerma ( K col ) in photon beams and to investigate total radiative yields for electrons and positrons as a functio...

journal_title：Medical physics

authors： Rogers DWO,Townson RW

更新日期：2019-11-01 00:00:00

abstract：:Intensity modulated radiation therapy (IMRT) with a dynamic multileaf collimator (DMLC) requires synchronization of DMLC leaf motion with dose delivery. A delay in DMLC communication is known to cause leaf lag and lead to dosimetric errors. The errors may be exacerbated by gated operation. The purpose of this study wa...

journal_title：Medical physics

authors： Duan J,Shen S,Fiveash JB,Brezovich IA,Popple RA,Pareek PN

更新日期：2003-08-01 00:00:00

abstract：:A micro-angiographic detector was designed and its performance was previously tested to evaluate its feasibility as an improvement over current x-ray detectors for neuro-interventional imaging. The detector was shown to have a modulation transfer function value of about 2% at the Nyquist frequency of 10 cycles/mm and ...

journal_title：Medical physics

authors： Ganguly A,Rudin S,Bednarek DR,Hoffmann KR

更新日期：2003-11-01 00:00:00

abstract：:The scattered-photon part of pencil-beam dose kernels for high-energy x-ray beams can be derived experimentally by differentiating the broad-beam scatter-to-primary dose ratio as a function of radius. Formally, this requires a uniform and parallel beam, and the procedure is complicated by the nonideal, actual beam con...

journal_title：Medical physics

authors： Ceberg CP,Bjärngard BE

更新日期：1996-09-01 00:00:00

abstract：:Charge coupled devices (CCDs) are being increasingly used in radiation therapy for dosimetric purposes. However, CCDs are sensitive to stray radiation. This effect induces transient noise. Radiation-induced noise strongly alters the image and therefore limits its quantitative analysis. The purpose of this work is to c...

journal_title：Medical physics

authors： Archambault L,Briere TM,Beddar S

更新日期：2008-10-01 00:00:00

abstract：PURPOSE:A modular phantom for dosimetry and imaging performance evaluation in cone-beam computed tomography (CBCT) is reported, providing a tool for quantitative technical assessment that can be adapted to a broad variety of CBCT imaging configurations and clinical applications. METHODS:The phantom presents a set of m...

journal_title：Medical physics

authors： Siewerdsen JH,Uneri A,Hernandez AM,Burkett GW,Boone JM

更新日期：2020-02-01 00:00:00

abstract：:Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared wit...

journal_title：Medical physics

authors： Prisciandaro JI,Frechette CM,Herman MG,Brown PD,Garces YI,Foote RL

更新日期：2004-11-01 00:00:00

abstract：PURPOSE:The image quality of dedicated cone beam breast CT (CBBCT) is limited by substantial scatter contamination, resulting in cupping artifacts and contrast-loss in reconstructed images. Such effects obscure the visibility of soft-tissue lesions and calcifications, which hinders breast cancer detection and diagnosis...

journal_title：Medical physics

authors： Shi L,Vedantham S,Karellas A,Zhu L

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with du...

journal_title：Medical physics

authors： Johnston SM,Johnson GA,Badea CT

更新日期：2012-08-01 00:00:00

abstract：PURPOSE:A multi-institution dosimetry intercomparison has been undertaken of prostate intensity modulated radiation therapy (IMRT) delivery. The dosimetry intercomparison was incorporated into the quality assurance for site credentialing for the Trans-Tasman Radiation Oncology Group Prostate Fractionated Irradiation Tr...

journal_title：Medical physics

authors： Healy B,Frantzis J,Murry R,Martin J,Plank A,Middleton M,Catton C,Kron T

更新日期：2013-07-01 00:00:00

abstract：PURPOSE:Radiation therapy is often delivered by multiple sequential treatment plans. For an accurate radiobiological evaluation of the overall treatment, fractionation corrections to each dose distribution must be applied before summing the three-dimensional dose matrix of each plan since the simpler approach of perfor...

journal_title：Medical physics

authors： Mavroidis P,Ferreira BC,Papanikolaou N,Lopes Mdo C

更新日期：2013-03-01 00:00:00

abstract：:We compare the results of absorbed dose determined at reference conditions according to the AAPM TG-21 dose calibration protocol and the new AAPM TG-51 protocol. The AAPM TG-21 protocol for absorbed dose calibration is based on ionization chambers having exposure calibration factors for 60Co gamma rays, N(x). The new ...

journal_title：Medical physics

authors： Ding GX,Cygler JE,Kwok CB

更新日期：2000-06-01 00:00:00

abstract：PURPOSE:The treatment of moving targets with scanned proton beams is challenging. For motion mitigation, an Active Breathing Coordinator (ABC) can be used to assist breath-holding. The delivery of pencil beam scanning fields often exceeds feasible breath-hold durations, requiring high breath-hold reproducibility. We ev...

journal_title：Medical physics

authors： den Otter LA,Kaza E,Kierkels RGJ,Meijers A,Ubbels FJF,Leach MO,Collins DJ,Langendijk JA,Knopf AC

更新日期：2018-12-01 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