A dual cone-beam CT system for image guided radiotherapy: initial performance characterization.

abstract：PURPOSE:A radiophotoluminescent glass rod dosimeter (RGD) has recently become commercially available. It is being increasingly used for dosimetry in radiotherapy to measure the absorbed dose including scattered low-energy photons on the body surface of a patient and for postal dosimetry audit. In this article, the dosi...

journal_title：Medical physics

authors： Kadoya N,Shimomura K,Kitou S,Shiota Y,Fujita Y,Dobashi S,Takeda K,Jingu K,Matsushita H,Namito Y,Ban S,Koyama S,Tabushi K

更新日期：2012-10-01 00:00:00

abstract：PURPOSE:To evaluate two deformable image registration (DIR) algorithms for the purpose of contour mapping to support image guided adaptive radiotherapy (IGART) with 4D cone beam CT (4DCBCT). METHODS:Eleven locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan- beam CT (4DFBCT) and ...

journal_title：Medical physics

authors： Balik S,Hugo G,Weiss E,Jan N,Roman N,Sleeman W,Fatyga M,Christensen G,Murphy M,Lu J,Keall P,Williamson J

更新日期：2012-06-01 00:00:00

abstract：:This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). In particular, the option of producing a therapy beam at an orthogonal direction to the incoming protons is considered. Monte Carlo radiation transport simulations, both with and wit...

journal_title：Medical physics

authors： Allen DA,Beynon TD,Green S

更新日期：1999-01-01 00:00:00

abstract：:The relationship between the pixel value and exit dose was investigated for a new commercially available amorphous silicon electronic portal imaging device. The pixel to dose mapping function was established to be linear for detector distances between 116.5 cm to 150 cm from the source, radiation field sizes from 5 x ...

journal_title：Medical physics

authors： Grein EE,Lee R,Luchka K

更新日期：2002-10-01 00:00:00

abstract：:This paper proposes a new respiratory gated radiation treatment system that allows real-time tumor localization while avoiding invasive operation to a patient. The proposed system employs a three-dimensional (3D) ultrasound device, a 3D digital localizer, and a real-time image processing system. At the planning time, ...

journal_title：Medical physics

authors： Sawada A,Yoda K,Kokubo M,Kunieda T,Nagata Y,Hiraoka M

更新日期：2004-02-01 00:00:00

abstract：:Contemporary reconstruction methods employed for clinical helical cone-beam computed tomography (CT) are analytical (noniterative) but mathematically nonexact, i.e., the reconstructed image contains so called cone-beam artifacts, especially for higher cone angles. Besides cone artifacts, these methods also suffer from...

journal_title：Medical physics

authors： Sunnegårdh J,Danielsson PE

更新日期：2008-09-01 00:00:00

abstract：PURPOSE:In computed tomography (CT), organ dose, effective dose, and risk index can be estimated from volume-weighted CT dose index (CTDI(vol)) or dose-length product (DLP) using conversion coefficients. Studies have investigated how these coefficients vary across scanner models, scan parameters, and patient size. Howe...

journal_title：Medical physics

authors： Li X,Samei E,Williams CH,Segars WP,Tward DJ,Miller MI,Ratnanather JT,Paulson EK,Frush DP

更新日期：2012-11-01 00:00:00

abstract：PURPOSE:The purposes of this study is to measure the low frequency drop (LFD) of the modulation transfer function (MTF), associated with the long tails of the detector point spread function (PSF) of an on-board flat panel imager and study its impact on cone-beam CT (CBCT) image quality and scatter measurement accuracy....

journal_title：Medical physics

authors： Lazos D,Williamson JF

更新日期：2012-09-01 00:00:00

abstract：:We present a theoretical development and experimental verification of a description of power loss and sample resistance for a lossy sample in a nuclear magnetic resonance radio frequency coil for a sample geometry where the eddy current streamlines are disrupted from their usually assumed circular paths. Specifically ...

journal_title：Medical physics

authors： Harpen MD

更新日期：1989-09-01 00:00:00

abstract：:A calculation is described that enables the rapid assessment of dose rate at various points of interest within the eye (lens, optic nerve, etc.) for the treatment of choroidal melanoma by plaque therapy. 125I seeds are used as the radiation source. The location of the plaque and its associated seeds relative to the ey...

journal_title：Medical physics

authors： Kepka AG,Johnson PM,Kline RW

更新日期：1988-05-01 00:00:00

abstract：PURPOSE:In medical imaging, data scaling is sometimes desired to handle the system complexity, such as uniformity calibration. Since the data are usually saved in short integer, conventional data scaling will first scale the data in floating point format and then truncate or round the floating point data to short integ...

journal_title：Medical physics

authors： Bai C,Conwell R,Kindem J

更新日期：2010-06-01 00:00:00

abstract：PURPOSE:Periodic MV∕KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging do...

journal_title：Medical physics

authors： Zhang P,Hunt M,Happersett L,Cox B,Mageras G

更新日期：2012-09-01 00:00:00

abstract：PURPOSE:Color images are visualized on medical monitors that are adjusted by a grayscale standard display function (GSDF) or γ2.2. Although the GSDF is visually displayed as a linear graded grayscale, it does not specify how color medical images should be presented. On the other hand, the usual gamma setting for color ...

journal_title：Medical physics

authors： Shibutani T,Onoguchi M,Yoneyama H,Nakajima K,Matsuo S,Bamba Y,Saito S

更新日期：2019-06-01 00:00:00

abstract：:Current edge detection methods used to determine coronary artery dimensions from digital (DSA) images suffer a strong dependence on the system's modulation transfer function (MTF). The videodensitometric algorithms are less sensitive to MTF blurring, yet still result in an overestimation of the vessel size of 10% to 2...

journal_title：Medical physics

authors： Weber DM

更新日期：1989-03-01 00:00:00

abstract：:Monte Carlo (MC) techniques can be used to build a simulation model of an electron accelerator to calculate output factors for electron fields. This can be useful during commissioning of electron beams from a linac and in clinical practice where irregular fields are also encountered. The Monte Carlo code BEAM/EGS4 was...

journal_title：Medical physics

authors： Verhaegen F,Mubata C,Pettingell J,Bidmead AM,Rosenberg I,Mockridge D,Nahum AE

更新日期：2001-06-01 00:00:00

abstract：PURPOSE:The spatial and temporal tracking performance of a commercially available 3D optical surface imaging system is evaluated for its potential use in frameless stereotactic radiosurgery head tracking applications. METHODS:Both 3D surface and infrared (IR) marker tracking were performed simultaneously on a head pha...

journal_title：Medical physics

authors： Wiersma RD,Tomarken SL,Grelewicz Z,Belcher AH,Kang H

更新日期：2013-11-01 00:00:00

abstract：PURPOSE:This paper describes the low-kV spectral optimization of dual-energy CT (DECT) equipped with high-kV tin filtration for the quantitative acquisition of electron density information, which is essential for treatment planning in radiotherapy. In addition, an analytical DECT image simulation was preliminarily perf...

journal_title：Medical physics

authors： Saito M

更新日期：2011-06-01 00:00:00

abstract：:Transthoracic electrical impedance Z consists of a constant baseline component Z0 and the time variable component delta Z such that Z = Z0 + delta Z. The first time derivative of Z has a negative peak, the magnitude of which is (dZ/dt)min. Measurements of 170 volunteers show that (dZ/dt)min is a function of the consta...

journal_title：Medical physics

authors： Djordjevich L,Sadove MS

更新日期：1981-01-01 00:00:00

abstract：:Stereotactic Body Radiation Therapy (SBRT) is being increasingly used in the radiation oncology community to treat tumors in extra-cranial sites such as spine, lung, liver, pancreas and prostate. There are well established RTOG protocols (e.g. RTOG 0631 for spine, RTOG 0813 and 0915 for lung and RTOG 0438 for liver) t...

journal_title：Medical physics

authors： Hong L

更新日期：2012-06-01 00:00:00

abstract：:It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a wa...

journal_title：Medical physics

authors： Joseph PM,Shetty A,Bonaroti EA

更新日期：1987-07-01 00:00:00

abstract：:The verification of dose distributions with high dose gradients as appearing in brachytherapy or stereotactic radiotherapy for example, calls for dosimetric methods with sufficiently high spatial resolution. Polymer gels in combination with a MR or optical scanner as a readout device have the potential of performing t...

journal_title：Medical physics

authors： Bayreder C,Schön R,Wieland M,Georg D,Moser E,Berg A

更新日期：2008-05-01 00:00:00

abstract：PURPOSE:The authors investigated the performance of a recently introduced 160-mm/256-row CT system for low dose quantitative myocardial perfusion (MP) imaging of the whole heart. This platform is equipped with a gantry capable of rotating at 280 ms per full cycle, a second generation of adaptive statistical iterative r...

journal_title：Medical physics

authors： So A,Imai Y,Nett B,Jackson J,Nett L,Hsieh J,Wisenberg G,Teefy P,Yadegari A,Islam A,Lee TY

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:Hybrid radiotherapy-MRI devices promise real time tracking of moving tumors to focus the radiation portals to the tumor during irradiation. This approach will benefit from the increased temporal resolution of MRI's data acquisition and reconstruction. In this work, the authors propose a novel spatial-temporal c...

journal_title：Medical physics

authors： Yip E,Yun J,Wachowicz K,Heikal AA,Gabos Z,Rathee S,Fallone BG

更新日期：2014-08-01 00:00:00

abstract：PURPOSE:Deformable registration generally relies on the assumption that the sought spatial transformation is smooth. Yet, breathing motion involves sliding of the lung with respect to the chest wall, causing a discontinuity in the motion field, and the smoothness assumption can lead to poor matching accuracy. In respon...

journal_title：Medical physics

authors： Vandemeulebroucke J,Bernard O,Rit S,Kybic J,Clarysse P,Sarrut D

更新日期：2012-02-01 00:00:00

abstract：PURPOSE:Dual source CT (DSCT) systems utilize two measurement systems (A) and (B) offset by about 90 degrees. A special challenge in DSCT is cross-scattered radiation, i.e., scattered radiation from x-ray tube (B) detected in detector (A) and vice versa. Cross-scattered radiation can produce artifacts and degrade the c...

journal_title：Medical physics

authors： Petersilka M,Stierstorfer K,Bruder H,Flohr T

更新日期：2010-11-01 00:00:00

abstract：PURPOSE:The need for an accurate lesion segmentation tool in 18FDG PET is a prerequisite for the estimation of lesion response to therapy, for radionuclide dosimetry, and for the application of 18FDG PET to radiotherapy planning. In this work, the authors have developed an iterative method based on a mathematical fit d...

journal_title：Medical physics

authors： Nehmeh SA,El-Zeftawy H,Greco C,Schwartz J,Erdi YE,Kirov A,Schmidtlein CR,Gyau AB,Larson SM,Humm JL

更新日期：2009-10-01 00:00:00

abstract：:Treatment of cervical cancer often involves intracavitary high dose rate (HDR) brachytherapy. Dose delivered to the bladder and rectum are typically estimated using the ICRU reference points. Dose to the sigmoid and small bowel are not estimated, yet these organs typically exhibit significant complication rates. The o...

journal_title：Medical physics

authors： Lekx-Toniolo KS,Hunter R,Patel M,Voruganti S,Johanson C,Dhamanaskar K,Farrell T

更新日期：2008-07-01 00:00:00

abstract：:This paper presents a numerical investigation of the effective point of measurement of thimble ionization chambers in megavoltage photon beams using Monte Carlo simulations with the EGSNRC system. It is shown that the effective point of measurement for relative photon beam dosimetry depends on every detail of the cham...

journal_title：Medical physics

authors： Kawrakow I

更新日期：2006-06-01 00:00:00

abstract：:The purpose of this work is to compare the efficacy of mathematical models in predicting the occurrence of radiotherapy-induced left ventricular perfusion defects assessed using single-photon emission computed tomography (SPECT). The basis of this study is data from 73 left-sided breast/ chestwall patients treated wit...

journal_title：Medical physics

authors： Das SK,Baydush AH,Zhou S,Miften M,Yu X,Craciunescu O,Oldham M,Light K,Wong T,Blazing M,Borges-Neto S,Dewhirst MW,Marks LB

更新日期：2005-01-01 00:00:00

abstract：:The purpose of the present study is to characterize electron contamination in photon beams in different clinical situations. Variations with field size, beam modifier (tray, shaping block) and source-surface distance (SSD) were studied. Percentage depth dose measurements with and without a purging magnet and replacing...

journal_title：Medical physics

authors： Lopez Medina A,Teijeiro A,Garcia J,Esperon J,Terron JA,Ruiz DP,Carrion MC

更新日期：2005-05-01 00:00:00