Ray-based approach to skeletal muscle perfusion measurement on interventional x-ray systems.

abstract：PURPOSE:MR thermometry based on the proton resonance frequency shift (PRFS) is the most commonly used method for the monitoring of thermal therapies. As the chemical shift of water protons is temperature dependent, the local temperature variation (relative to an initial baseline) may be calculated from time-dependent p...

journal_title：Medical physics

authors： Viallon M,Terraz S,Roland J,Dumont E,Becker CD,Salomir R

更新日期：2010-04-01 00:00:00

abstract：PURPOSE:The purpose of this study is to adapt an equivalent source model originally developed for conventional CT Monte Carlo dose quantification to the radiation oncology context and validate its application for evaluating concomitant dose incurred by a kilovoltage (kV) cone-beam CT (CBCT) system integrated into a lin...

journal_title：Medical physics

authors： McMillan K,McNitt-Gray M,Ruan D

更新日期：2013-11-01 00:00:00

abstract：PURPOSE:The purpose of this work was to investigate the use of an experimental complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) for tracking of moving fiducial markers during radiotherapy. METHODS:The APS has an active area of 5.4 × 5.4 cm and maximum full frame read-out rate of 20 frame s(-1),...

journal_title：Medical physics

authors： Osmond JP,Zin HM,Harris EJ,Lupica G,Allinson NM,Evans PM

更新日期：2011-11-01 00:00:00

abstract：PURPOSE:Intensity-Modulated Radiation Therapy (IMRT), including its variations (including IMRT, Volumetric Arc Therapy (VMAT), and Tomotherapy), is a widely used and critically important technology for cancer treatment. It is a knowledge-intensive technology due not only to its own technical complexity, but also to the...

journal_title：Medical physics

authors： Ge Y,Wu QJ

更新日期：2019-06-01 00:00:00

abstract：PURPOSE:To characterize a new air vented ionization chamber technology, suitable to build detector arrays with small pixel pitch and independence of sensitivity on dose per pulse. METHODS:The prototype under test is a linear array of air vented ionization chambers, consisting of 80 pixels with 3.5 mm pixel pitch dista...

journal_title：Medical physics

authors： Togno M,Wilkens JJ,Menichelli D,Oechsner M,Perez-Andujar A,Morin O

更新日期：2016-05-01 00:00:00

abstract：:Results of an 18-alternative forced-choice experiment have shown that observers were capable of detecting a signal with a contrast of 1 in terms of 10-bit data which were displayed on a CRT monitor with an 8-bit video generator and a window width setting of 1024. We investigated the conditions under which 10-bit signa...

journal_title：Medical physics

authors： Giger ML,Ohara K,Doi K

更新日期：1986-05-01 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：:A spread-out Bragg peak (SOBP) is used in proton beam therapy to create a longitudinal conformality of the required dose to the target. In order to create this effect in a passive beam scattering system, a variety of components must operate in conjunction to produce the desired beam parameters. We will describe how th...

journal_title：Medical physics

authors： Lu HM,Brett R,Engelsman M,Slopsema R,Kooy H,Flanz J

更新日期：2007-10-01 00:00:00

abstract：PURPOSE:The aim of in vivo skin dosimetry was to measure the absorbed dose to the skin during radiotherapy, when treatment planning calculations cannot be relied on. It is of particularly importance in hypo-fractionated stereotactic modalities, where excessive dose can lead to severe skin toxicity. Currently, commercia...

journal_title：Medical physics

authors： Vicoroski N,Espinoza A,Duncan M,Oborn BM,Carolan M,Metcalfe P,Menichelli D,Perevertaylo VL,Lerch MLF,Rosenfeld AB,Petasecca M

更新日期：2017-10-01 00:00:00

abstract：:During our routine calibration of a Varian Clinac-20 linear accelerator, the absorbed dose for a fixed monitor unit (mu) was found to decrease with increasing dose rate. Between dose rates of 100 and 500 mu/min, there was up to 20% difference in absorbed dose for a 20-MeV electron beam. The cause of this problem was a...

journal_title：Medical physics

authors： Cheng PC,Kubo H

更新日期：1988-09-01 00:00:00

abstract：:In external beam radiotherapy, electronic portal imaging becomes more and more an indispensable tool for the verification of the patient setup. For the safe clinical introduction of high dose conformal radiotherapy like intensity modulated radiation therapy, on-line patient setup verification is a prerequisite to ensu...

journal_title：Medical physics

authors： Vetterli D,Riem H,Aebersold DM,Greiner RH,Manser P,Cossmann P,Kemmerling L,Born EJ,Mini R

更新日期：2004-04-01 00:00:00

abstract：PURPOSE:To accurately and efficiently implement charged particle transport in a magnetic field in EGSnrc and validate the code for the use in phantom and ion chamber simulations. METHODS:The effect of the magnetic field on the particle motion and position is determined using one- and three-point numerical integrations...

journal_title：Medical physics

authors： Malkov VN,Rogers DW

更新日期：2016-07-01 00:00:00

abstract：:The nuclear magnetic resonance phenomenon has given rise to both magnetic resonance imaging, which yields morphologic data, and magnetic resonance spectroscopy (MRS), which yields chemical data. In humans these data are derived principally from the resonances of the hydrogen nucleus in the low molecular weight compoun...

journal_title：Medical physics

authors： Prost RW

更新日期：2008-10-01 00:00:00

abstract：PURPOSE:To develop a method of (a) calculating the dose rate of voxels within a proton field delivered using pencil beam scanning (PBS), and (b) reporting a representative dose rate for the PBS treatment field that enables correspondence between multiple treatment modalities. This method takes into account the unique s...

journal_title：Medical physics

authors： Folkerts MM,Abel E,Busold S,Perez JR,Krishnamurthi V,Ling CC

更新日期：2020-12-01 00:00:00

abstract：:The commonly used Blunck and Leisegang electron energy-loss distribution falls off too rapidly with increasing energy loss. Also, for large thicknesses and/or low-Z media, where their distribution should approach Landau's, it normalizes to 0.92 rather than 1.0, it overestimates the number of very small energy-loss eve...

journal_title：Medical physics

authors： Weinhous MS,Nath R

更新日期：1984-05-01 00:00:00

abstract：PURPOSE:Lung cancer is a major cause of cancer deaths, and the 5-year survival rate of stage IV lung cancer patients is only 2%. However, the 5-year survival rate of stage I lung cancer patients significantly increases to 50%. As such, spiral computed tomography (CT) scans are necessary to diagnose high-risk lung cance...

journal_title：Medical physics

authors： Ma J,Zhou Z,Ren Y,Xiong J,Fu L,Wang Q,Zhao J

更新日期：2017-08-01 00:00:00

abstract：PURPOSE:In prostate radiotherapy, dose distribution may be calculated on CT images, while the MRI can be used to enhance soft tissue visualization. Therefore, a registration between MR and CT images could improve the overall treatment planning process, by improving visualization with a demonstrated interobserver deline...

journal_title：Medical physics

authors： Hamdan I,Bert J,Rest CCL,Tasu JP,Boussion N,Valeri A,Dardenne G,Visvikis D

更新日期：2017-12-01 00:00:00

abstract：PURPOSE:Upgrade and benchmarking of a research 4D treatment planning system (4DTPS) suitable for realistic patient treatment planning and treatment simulations taking into account specific requirements for scanned ion beam therapy, i.e., modeling of dose heterogeneities due to interplay effects and range changes caused...

journal_title：Medical physics

authors： Richter D,Schwarzkopf A,Trautmann J,Krämer M,Durante M,Jäkel O,Bert C

更新日期：2013-05-01 00:00:00

abstract：:Magnetic resonance (MR) measurements of relaxation times and diffusion coefficient in tissue have been demonstrated to be sensitive to biological changes induced by radiation therapy. We are currently using mouse models of human glioblastoma multiforme (GBM) to study tumour response to ionizing radiation by MRI at 9.4...

journal_title：Medical physics

authors： Larocque M,Syme A,Fallone BG

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:The limited-angle intrafractional verification (LIVE) system was developed to track tumor movement during stereotactic body radiation therapy (SBRT). However, the four-dimensional (4D) MV/kV imaging procedure results in additional radiation dose to patients. This study is to quantify imaging radiation dose from...

journal_title：Medical physics

authors： Ding GX,Zhang Y,Ren L

更新日期：2019-06-01 00:00:00

abstract：:A theoretical analysis of the x-ray phase contrast imaging and its validation via synchrotron radiation imaging is here presented. Two different mathematical models have been followed: the simpler ray-optical approach and the more rigorous Fresnel-Kirchoff diffraction theory. Subsequently, the conditions upon which th...

journal_title：Medical physics

authors： Peterzol A,Olivo A,Rigon L,Pani S,Dreossi D

更新日期：2005-12-01 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：PURPOSE:To develop a probabilistic treatment planning (PTP) method which is robust to systematic patient setup errors and to compare PTP plans with plans generated using a planning target volume (PTV) margin optimized to give the same target coverage probability as the PTP plan. METHODS:Plans adhering to the RTOG-0126...

journal_title：Medical physics

authors： Moore JA,Gordon JJ,Anscher M,Silva J,Siebers JV

更新日期：2012-02-01 00:00:00

abstract：:Using stable materials capable of mimicking any soft tissues of the human body--quantitatively with respect to speed of sound, density, and attenuation coefficient and semiquantitatively with respect to scatter--we have constructed a torso section phantom containing simulated bowel gas, kidney, kidney fat pad, liver, ...

journal_title：Medical physics

authors： Madsen EL,Zagzebski JA,Ghilardi-Netto T

更新日期：1980-01-01 00:00:00

abstract：PURPOSE:At our institution, all proton patient plans undergo patient-specific quality assurance (PSQA) prior to treatment delivery. For intensity-modulated proton beam therapy, quality assurance is complex and time consuming, and it may involve multiple measurements per field. We reviewed our PSQA workflow and identifi...

journal_title：Medical physics

authors： Hernandez Morales D,Shan J,Liu W,Augustine KE,Bues M,Davis MJ,Fatyga M,Johnson JE,Mundy DW,Shen J,Younkin JE,Stoker JB

更新日期：2019-01-01 00:00:00

abstract：PURPOSE:In fluoroscopy-guided clinical procedures that involve tracking objects over long treatment times, there is a need for reducing the amount of imaging dose delivered to the patient and the operating staff. In this study, we introduce a feedback metric to minimize tube current while maintaining a targeting precis...

journal_title：Medical physics

authors： Siddique S,Fiume E,Jaffray D

更新日期：2012-06-01 00:00:00

abstract：:We have reported in our previous studies on the methodology, and feasibility of 4D-PET (Gated PET) acquisition, to reduce respiratory motion artifact in PET imaging of the thorax. In this study, we expand our investigation to address the problem of respiration motion in PET/CT imaging. The respiratory motion of four l...

journal_title：Medical physics

authors： Nehmeh SA,Erdi YE,Pan T,Pevsner A,Rosenzweig KE,Yorke E,Mageras GS,Schoder H,Vernon P,Squire O,Mostafavi H,Larson SM,Humm JL

更新日期：2004-12-01 00:00:00

abstract：:Projected light fields are used on treatment simulators and teletherapy treatment units to delineate the size and position of the radiation beam. Any discrepancy between these fields will lead to a systematic field placement error, with possibly serious implications with regard to the accuracy of the delivered dose di...

journal_title：Medical physics

authors： Luchka K,Chen D,Shalev S,Gluhchev G,Rajapakshe R

更新日期：1996-07-01 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

authors： Chen CC,Chang C,Moyers MF,Gao M,Mah D

更新日期：2016-02-01 00:00:00

abstract：PURPOSE:Our aim was to compare different magnet arrangements for magnetic cell delivery to human lower leg arteries and investigate the theoretical targeting efficiency under realistic flow conditions as a possible treatment after angioplasty. Additionally the potential of scaling down or translating the magnetic actua...

journal_title：Medical physics

authors： Riegler J,Lau KD,Garcia-Prieto A,Price AN,Richards T,Pankhurst QA,Lythgoe MF

更新日期：2011-07-01 00:00:00