Image-based 3D modeling study of the influence of vessel density and blood hemoglobin concentration on tumor oxygenation and response to irradiation.

abstract：:The visual observer performance for detecting low-contrast patterns by employing both the receiver operating characteristic (ROC) and the 9-alternative forced choice (9-AFC) method is investigated. For each observer and each experimental technique, the results were reproducible with respect to a repeated observation. ...

journal_title：Medical physics

authors： Herrmann C,Buhr E,Hoeschen D,Fan SY

更新日期：1993-05-01 00:00:00

abstract：PURPOSE:To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS:Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a...

journal_title：Medical physics

authors： Gregory WD,Marx JJ,Gregory CW,Mikkelson WM,Tjoe JA,Shell J

更新日期：2012-07-01 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：PURPOSE:In C-arm computed tomography (CT), the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g., a full hip or thorax. Proposed methods to extend the FOV use a fixed detector displacement and a 360° scan range to double the radius of the FOV. These trajectories are designed for...

journal_title：Medical physics

authors： Herbst M,Schebesch F,Berger M,Choi JH,Fahrig R,Hornegger J,Maier A

更新日期：2015-05-01 00:00:00

abstract：PURPOSE:A novel 3D printing method has been developed, which employs human CT images to construct patient specific phantoms by controlling the filament extrusion rate. METHODS:An in-house software was developed comprising pixel-by-pixel (PbP) reading of the Hounsfield Units (HU) values in the original patient DICOM im...

journal_title：Medical physics

authors： Okkalidis N

更新日期：2018-10-01 00:00:00

abstract：:The physical imaging performance of ST-V, ST-VA, and ST-VN computed radiography image plates, read with a Philips AC3 acquisition system, was investigated at 70 kVp with 0.5 mm of copper beam filtration for four different entrance air kerma values: 0.5, 2.6, 26, and 260 micro Gy. Measurements included characteristic r...

journal_title：Medical physics

authors： Kengyelics SM,Davies AG,Cowen AR

更新日期：1998-11-01 00:00:00

abstract：:This study concerns the accuracy and precision of the IAEA/WHO LiF TLD system used in intercomparison by mail of absorbed doses from 60Co gamma-radiation and 4-25 MV x rays. The system employs 160 mg LiF powder in polystyrene capsules, which are placed at 5 or 7 cm depth in water and irradiated to doses close to 200 r...

journal_title：Medical physics

authors： Bjärngard BE,Kase KR,Rudén BI,Biggs PJ,Boyer AL,Johansson KA

更新日期：1980-09-01 00:00:00

abstract：PURPOSE:Signal encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the region of interest. One way to increase the sensitivity of the method is to scan the region of interest with a field-free line (FFL) instead of the FFP. Recently, the first feasible FFL coil setup was i...

journal_title：Medical physics

authors： Knopp T,Erbe M,Biederer S,Sattel TF,Buzug TM

更新日期：2010-07-01 00:00:00

abstract：PURPOSE:4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this "after-the-fact" binning approach, however, projections are uneve...

journal_title：Medical physics

authors： Fast MF,Wisotzky E,Oelfke U,Nill S

更新日期：2013-09-01 00:00:00

abstract：PURPOSE:The measurement of malignant pleural mesothelioma is critical to the assessment of tumor response to therapy. Current response assessment standards utilize summed linear measurements acquired on three computed tomography (CT) sections. The purpose of this study was to evaluate manual area measurements as an alt...

journal_title：Medical physics

authors： Labby ZE,Straus C,Caligiuri P,MacMahon H,Li P,Funaki A,Kindler HL,Armato SG 3rd

更新日期：2013-08-01 00:00:00

abstract：:The availability of digital radiographic imaging on simulators has led to the investigation of a number of new imaging possibilities, including digital linear tomography (tomosynthesis). It has been shown that a single set of projections in this case is sufficient to reconstruct images from multiple planes, including ...

journal_title：Medical physics

authors： Zwicker RD,Atari NA

更新日期：1997-06-01 00:00:00

abstract：:The GEANT4 application for tomographic emission (GATE) is one of the most detailed Monte Carlo simulation tools for SPECT and PET. It allows for realistic phantoms, complex decay schemes, and a large variety of detector geometries. However, only a fraction of the information in each particle history is available for p...

journal_title：Medical physics

authors： De Beenhouwer J,Staelens S,Vandenberghe S,Verhaeghe J,Van Holen R,Rault E,Lemahieu I

更新日期：2009-04-01 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：:We have made a comparative investigation of the estimated spectra obtained by the Laplace transform analysis of the transmitted exposure data measured in an absorption study of a 4-MV x-ray beam. Four transform pair models currently used with this method have been evaluated. It has been determined that the Archer-Wagn...

journal_title：Medical physics

authors： Ahuja SD,Steward PG,Roy TS,Slessinger ED

更新日期：1986-05-01 00:00:00

abstract：BACKGROUND:X-ray dark-field radiography could enhance mammography by providing more information on imaged tissue and microcalcifications. The dark field signal is a measure of small angle scattering and can thus provide additional information on the imaged materials. This information can be useful for material distinct...

journal_title：Medical physics

authors： Rauch T,Rieger J,Pelzer G,Horn F,Erber R,Wunderle M,Emons J,Nabieva N,Fuhrich N,Michel T,Hartmann A,Fasching PA,Anton G

更新日期：2020-04-01 00:00:00

abstract：:Two or more angiograms are being used frequently in medical imaging to reconstruct locations in three-dimensional (3D) space, e.g., for reconstruction of 3D vascular trees, implanted electrodes, or patient positioning. A number of techniques have been proposed for this task. In this simulation study, we investigate th...

journal_title：Medical physics

authors： Dmochowski J,Hoffmann KR,Singh V,Xu J,Nazareth DP

更新日期：2005-09-01 00:00:00

abstract：PURPOSE:In Stereotactic body radiation therapy (SBRT) higher dose per fraction is delivered to patients and thus the need for an accurate dose computation is further elevated. However under such conditions of small field geometries, the electronic equilibrium can be lost, making it challenging for the dose-calculation ...

journal_title：Medical physics

authors： Shosha M,Deiab N,Eldib A,Tohamy K

更新日期：2012-06-01 00:00:00

abstract：:Administration of x-ray contrast agents during heart catheterization examination increases the absorbed radiation dose in tissue. To estimate the dose absorbed by the blood of children undergoing diagnostic heart catheterization and angiocardiography, a number of measurements and calculations were conducted. First, en...

journal_title：Medical physics

authors： Callisen HH,Norman A,Adams FH

更新日期：1979-11-01 00:00:00

abstract：:Inverse treatment planning of intensity-modulated radiation therapy (IMRT) is complicated by several sources of error, which can cause deviations of optimized plans from the true optimal solution. These errors include the systematic and convergence error, the local minima error, and the optimizer convergence error. We...

journal_title：Medical physics

authors： Hartmann M,Bogner L

更新日期：2008-05-01 00:00:00

abstract：PURPOSE:The Monte Carlo simulation of electron transport in Linac targets using the condensed history technique is known to be problematic owing to a potential dependence of absorbed dose distributions on the electron step length. In the PENELOPE code, the step length is partially determined by the transport parameters...

journal_title：Medical physics

authors： Rodriguez M,Sempau J,Brualla L

更新日期：2015-06-01 00:00:00

abstract：PURPOSE:In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts in CBCT images. Such gain variations can be caused by change in detector entrance exposure levels or beam hardening, and they are not accou...

journal_title：Medical physics

authors： Altunbas C,Lai CJ,Zhong Y,Shaw CC

更新日期：2014-09-01 00:00:00

abstract：:Direct comparisons of the National Institute of Standards and Technology's (NIST) Ritz 20 kV to 100 kV standard free-air ionization chamber and a portable variable-length free-air ionization chamber designed by the University of Wisconsin-Madison Accredited Dosimetry Calibration Laboratory (UW-ADCL) were made on NISTs...

journal_title：Medical physics

authors： Coletti JG,Pearson DW,DeWerd LA,O'Brien CM,Lamperti PJ

更新日期：1997-08-01 00:00:00

abstract：:The paper presents a theoretical derivation of the photon fluence simulation efficiency in photon beam treatment head simulations without and with bremsstrahlung splitting. The expressions obtained provide a rigorous explanation of the efficiency dependence on scoring zone size and splitting number and explain the lar...

journal_title：Medical physics

authors： Kawrakow I

更新日期：2005-07-01 00:00:00

abstract：PURPOSE:The lateral edge of a proton therapy beam is commonly used to achieve conformality to the treatment volume where critical structures reside close to the target. However, when treating shallow depths, the lateral edge of a pencil beam scanning (PBS) system may be broader than that of a double scattered (DS) syst...

journal_title：Medical physics

authors： Charlwood FC,Aitkenhead AH,Mackay RI

更新日期：2016-03-01 00:00:00

abstract：:The American Association of Physicists in Medicine recommends that the reference dose-rate distribution, used for treatment planning for low-energy photon brachytherapy sources in routine clinical use, must be based on at least two independent determinations: one using experimentally measured dose rates and one using ...

journal_title：Medical physics

authors： Chan GH,Nath R,Williamson JF,American Association of Physicists in Medicine.

更新日期：2004-05-01 00:00:00

abstract：PURPOSE:To track variations in the deformation of the arterial wall noninvasively by estimating the accumulated displacement and strain over a cardiac cycle may provide useful indicators of vascular health. METHODS:In this paper, we propose an approach to track a region of interest (ROI) locally and estimate arterial ...

journal_title：Medical physics

authors： Ge W,Krueger CG,Weichmann A,Shanmuganayagam D,Varghese T

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:This study aims to investigate the feasibility of using the images of the treatment fields acquired by an electronic portal imaging device (EPID) for real-time target localization. METHODS:Forty one patients treated with IMRT and RapidArc were recruited in this study including 37 prostate patients and 4 lung p...

journal_title：Medical physics

authors： Xu Q,Lin M,Chen X,Tong X,Fan J,Dong Z,Chen L,Ma C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Brachytherapy is a treatment modality which delivers large doses of radiation in a reduced number of visits. Since a small number of large dose-per-fraction is administered in high dose rate brachytherapy, ensuring the right dose is delivered is highly critical. In this work, a scintillation detector is coupled...

journal_title：Medical physics

authors： Tho D,Beaulieu L

更新日期：2019-05-01 00:00:00

abstract：:Lag in fluoroscopic systems introduces a frame-averaging effect that reduces measurements of image noise and incorrectly inflates measurements of the detective quantum efficiency (DQE). A correction can be implemented based on measurements of the temporal modulation transfer function (MTF). We introduce a method of me...

journal_title：Medical physics

authors： Friedman SN,Cunningham IA

更新日期：2008-06-01 00:00:00

abstract：PURPOSE:Power spectral analysis in radiographic images is conventionally performed using a windowed overlapping averaging periodogram. This study describes an alternative approach using a multitaper technique and compares its performance with that of the standard method. This tool will be valuable in power spectrum est...

journal_title：Medical physics

authors： Wu G,Mainprize JG,Yaffe MJ

更新日期：2012-02-01 00:00:00