Calculation of the biological effective dose for piecewise defined dose-rate fits.

abstract：PURPOSE:To study if malfunction of a receiver can be detected robustly using the simple ACR SNR measurement approach on a 32-channel head coil. METHODS:Standard ACR T1W images (11slice) were acquired with a commercial 32 channel head coil on a 3T Philips Achieva MR scanner following the ACR recommended setup. Raw data...

journal_title：Medical physics

authors： Peng Q

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Monte Carlo (MC) dose calculation is generally superior to analytical dose calculation (ADC) used in commercial TPS to model the dose distribution especially for heterogeneous sites, such as lung and head/neck patients. The purpose of this study was to provide a validated, fast, and open-source MC code, MCsquar...

journal_title：Medical physics

authors： Huang S,Souris K,Li S,Kang M,Barragan Montero AM,Janssens G,Lin A,Garver E,Ainsley C,Taylor P,Xiao Y,Lin L

更新日期：2018-12-01 00:00:00

abstract：:In x-ray spectral measurement using a semiconductor detector system, accurate positioning of the detector in front of the anode is very important. This needs accurate determination of the focal spot position on the target in an x-ray tube. We present a simple technique to determine the focal spot position accurately. ...

journal_title：Medical physics

authors： Kubota H,Ozaki Y,Matsumoto M,Kanamori H

更新日期：1993-07-01 00:00:00

abstract：:The authors describe a method for directly digitizing optical images with a photostimulable phosphor (PSP) system. A PSP plate is initially charged with an exposure to a uniform x-ray field, and is then exposed to an optical image which discharges the plate in relation to the amount of incident light. Two applications...

journal_title：Medical physics

authors： Dobbins JT 3rd,Chotas HG,Benveniste H

更新日期：1992-07-01 00:00:00

abstract：PURPOSE:The objectives of this study were (a) to devise a technique for measuring quantum noise in clinical body computed tomography (CT) images and (b) to develop a model for predicting that noise with high accuracy. METHODS:The study included 83 clinical image sets at two dose levels (clinical and 50% reduced dose l...

journal_title：Medical physics

authors： Tian X,Samei E

更新日期：2016-01-01 00:00:00

abstract：:The concept of the radiological depth is central to all algorithms which calculate radiation dose in a heterogeneous medium. For a discrete heterogeneous medium, consisting of regions of inhomogeneity, the radiological depth is usually presented as the sum over segments of the product of the segment length and the inh...

journal_title：Medical physics

authors： Siddon RL

更新日期：1985-01-01 00:00:00

abstract：:Wireless capsule endoscopy (WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal (GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which ...

journal_title：Medical physics

authors： Shamsudhin N,Zverev VI,Keller H,Pane S,Egolf PW,Nelson BJ,Tishin AM

更新日期：2017-08-01 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：:The propagation of noise in digitized images arrived at by algebraic manipulation of two images has been investigated. The algebraic manipulations investigated were logarithmic subtraction, linear subtraction, and division of the two images. The two images were identical except for the presence of a contrast-adding co...

journal_title：Medical physics

authors： Baily NA,Rimkus D,Nalcioglu O

更新日期：1983-01-01 00:00:00

abstract：PURPOSE:Flattening filters (FFs) have been considered as an integral part of the treatment head of a medical accelerator for more than 50 years. The reasons for the longstanding use are, however, historical ones. Advanced treatment techniques, such as stereotactic radiotherapy or intensity modulated radiotherapy have s...

journal_title：Medical physics

authors： Georg D,Knöös T,McClean B

更新日期：2011-03-01 00:00:00

abstract：:Intensity modulated radiation therapy (IMRT) treatment planning typically considers beam optimization and beam delivery as separate tasks. Following optimization, a multi-leaf collimator (MLC) or other beam delivery device is used to generate fluence patterns for patient treatment delivery. Due to limitations and char...

journal_title：Medical physics

authors： Siebers JV,Lauterbach M,Keall PJ,Mohan R

更新日期：2002-06-01 00:00:00

abstract：:A method for finding optimal primary fluence profiles for multiple field external beam radiation therapy techniques has been developed using a radiobiologically based objective function that quantifies the probability of achieving complication-free tumor control, P+. The objective function P+ has the valuable property...

journal_title：Medical physics

authors： Södertröm S,Brahme A

更新日期：1993-07-01 00:00:00

abstract：:In proton therapy, it is important to evaluate the field irradiated with protons and the deposited dose distribution in a patient's body. Positron emitters generated through fragmentation reactions of target nuclei can be used for this purpose. By detecting the annihilation gamma rays from the positron emitters, the a...

journal_title：Medical physics

authors： Inaniwa T,Kohno T,Yamagata F,Tomitani T,Sato S,Kanazawa M,Kanai T,Urakabe E

更新日期：2007-05-01 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：PURPOSE:To quantify detector perturbation effects in megavoltage small photon fields and support the theoretical explanation on the nature of quality correction factors in these conditions. METHODS:In this second paper, a modern approach to radiation dosimetry is defined for any detector and applied to small photon fi...

journal_title：Medical physics

authors： Bouchard H,Kamio Y,Palmans H,Seuntjens J,Duane S

更新日期：2015-10-01 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

authors： Lewis D,Micke A,Yu X,Chan MF

更新日期：2012-10-01 00:00:00

abstract：PURPOSE:to use complementary cine EPID and gimbals log file analysis for in-vivo tracking accuracy monitoring. METHODS:A clinical prototype of dynamic tracking (DT) was installed on the Vero SBRT system. This prototype version allowed tumor tracking by gimballed linac rotations using an internal-external correspondenc...

journal_title：Medical physics

authors： Poels K,Depuydt T,Verellen D,De Ridder M

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Computed tomography (CT) and, in particular, cone beam CT (CBCT) have been increasingly used as a diagnostic tool in recent years. Patient motion during acquisition is common in CBCT due to long scan times. This results in degraded image quality and may potentially increase the number of retakes. Our aim was to...

journal_title：Medical physics

authors： Niebler S,Schömer E,Tjaden H,Schwanecke U,Schulze R

更新日期：2019-10-01 00:00:00

abstract：:Neutron and photon energy spectra were measured in different depths and lateral positions in tissue-equivalent phantoms exposed to a therapeutical 14.1 MeV neutron beam. Intensity weighted mass energy absorption coefficients were derived for application in ionization chamber dosimetry in mixed neutron-gamma fields. Th...

journal_title：Medical physics

authors： Schmidt R,Magiera E,Scobel W

更新日期：1980-09-01 00:00:00

abstract：:A method is proposed for realistic simulation of the breast ductal network as part of a computer three-dimensional (3-D) breast phantom. The ductal network is simulated using tree models. Synthetic trees are generated based upon a description of ductal branching by ramification matrices (R matrices), whose elements re...

journal_title：Medical physics

authors： Bakic PR,Albert M,Brzakovic D,Maidment AD

更新日期：2003-07-01 00:00:00

abstract：PURPOSE:Contrast-enhanced imaging of the breast is frequently used in breast MRI and has recently become more common in mammography. The purpose of this study was to make single-scan contrast-enhanced imaging feasible for photon-counting breast CT (pcBCT) and to assess the spectral performance of a pcBCT scanner by eva...

journal_title：Medical physics

authors： Ruth V,Kolditz D,Steiding C,Kalender WA

更新日期：2020-07-01 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：PURPOSE:To use EGSnrc Monte Carlo simulations for magnetic field dosimetry to determine optimal measurement orientations, calculate beam quality conversion factors for 32 cylindrical and three parallel-plate (PP) ion chambers, evaluate the beam quality and angular dependence of these factors, and examine the magnetic f...

journal_title：Medical physics

authors： Malkov VN,Rogers DWO

更新日期：2018-02-01 00:00:00

abstract：PURPOSE:An improved method of image guidance for lung tumor biopsies could help reduce the high rate of false negatives. The aim of this work is to optimize the geometry of the scanning-beam digital tomography system (SBDX) for providing real-time 3D tomographic reconstructions for target verification. The unique geome...

journal_title：Medical physics

authors： Nelson G,Yoon S,Krishna G,Wilfley B,Fahrig R

更新日期：2013-11-01 00:00:00

abstract：:The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the de...

journal_title：Medical physics

authors： Wang G,Vannier MW

更新日期：1999-12-01 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

authors： Mercure E,Deprez JF,Fromageau J,Basset O,Soulez G,Cloutier G,Maurice RL

更新日期：2011-02-01 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：PURPOSE:Statistical modeling of an ultrasound backscattered echo envelope is used for tissue characterization. However, in the presence of complex structures within the analyzed area, estimation of parameters is disturbed and unreliable, e.g., in the case of breast tumor classification. In order to improve the differen...

journal_title：Medical physics

authors： Byra M,Nowicki A,Wróblewska-Piotrzkowska H,Dobruch-Sobczak K

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:X-ray microbeam radiation therapy is a preclinical concept for tumor treatment promising tissue sparing and enhanced tumor control. With its spatially separated, periodic micrometer-sized pattern, this method requires a high dose rate and a collimated beam typically available at large synchrotron radiation faci...

journal_title：Medical physics

authors： Burger K,Urban T,Dombrowsky AC,Dierolf M,Günther B,Bartzsch S,Achterhold K,Combs SE,Schmid TE,Wilkens JJ,Pfeiffer F

更新日期：2020-10-01 00:00:00

abstract：PURPOSE:The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring a...

journal_title：Medical physics

authors： Scarboro SB,Cody D,Alvarez P,Followill D,Court L,Stingo FC,Zhang D,McNitt-Gray M,Kry SF

更新日期：2015-04-01 00:00:00