Comments on "Sampling techniques for the evaluation of treatment plans" [Med. Phys. 20, 151-161 (1993)].

abstract：PURPOSE:To determine the diagnostic efficacy of optical coherence tomography (OCT) to identify cervical intraepithelial neoplasia (CIN) grade 2 or higher by computer-aided diagnosis (CADx). METHODS:OCT has been investigated as a screening/diagnostic tool in the management of preinvasive and early invasive cancers of t...

journal_title：Medical physics

authors： Kang W,Qi X,Tresser NJ,Kareta M,Belinson JL,Rollins AM

更新日期：2011-01-01 00:00:00

abstract：PURPOSE:Since the first publications on intensity modulated radiation therapy (IMRT) in the early 1980s almost all efforts have been focused on fairly time consuming dynamic or segmental multileaf collimation. With narrow fast scanned photon beams, the flexibility and accuracy in beam shaping increases, not least in co...

journal_title：Medical physics

authors： Andreassen B,Strååt SJ,Holmberg R,Näfstadius P,Brahme A

更新日期：2011-08-01 00:00:00

abstract：:Adaptive histogram equalization techniques are known to be effective for the enhancement of contrast in portal images acquired during radiotherapy treatments. A significant drawback is the loss of definition on the edges of the treatment field. Analysis of this problem shows that it can be remedied by separating the t...

journal_title：Medical physics

authors： Leszczynski KW,Shalev S,Cosby NS

更新日期：1992-05-01 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：:With intensity-modulated radiotherapy (IMRT), a variety of user-defined dose distribution can be produced using inverse planning. The generalized equivalent uniform dose (gEUD) has been used in IMRT optimization as an alternative objective function to the conventional dose-volume-based criteria. The purpose of this st...

journal_title：Medical physics

authors： Wu Q,Djajaputra D,Liu HH,Dong L,Mohan R,Wu Y

更新日期：2005-05-01 00:00:00

abstract：PURPOSE:In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to e...

journal_title：Medical physics

authors： Andreasen D,Van Leemput K,Hansen RH,Andersen JA,Edmund JM

更新日期：2015-04-01 00:00:00

abstract：:During the past decade the use of undersampled acquisition and constrained reconstruction have led to significant increases in data acquisition speed, SNR, spatial resolution and temporal resolution in MR imaging. When a separately acquired constraining image is combined with an angiographic time series the traditiona...

journal_title：Medical physics

authors： Mistretta C

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The repair rate conventionally assumed to be constant during the entire radiation course. However, increasing evidences from animal studies show that the repair process may slow down with time and the experimental data does not fit an exponential pattern. To address this enigma, we presented a generalized linea...

journal_title：Medical physics

authors： Huang Z,Mayr NA,Lo SS,McLawhorn R,Gao M,Liu T,Yuh W

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To show that Cherenkov emission is generated by external radiotherapy beam in tissue, and could serve as optical source to excite an oxygen sensitive phosphor, Oxyphor G4, within tissue. The intensity and lifetime of the phosphorescence was measured with a time-gated system and reveals the oxygenation levels in...

journal_title：Medical physics

authors： Zhang R,Kanick S,Vinogradov S,Esipova T,Pogue B

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The most common material for shielding is concrete, which can be made using various materials of different densities as aggregates. New techniques in radiotherapy, as IMRT and VMAT, require more monitor units and it is important to develop specifically designed shielding materials. METHODS:Arraela S.L. has dev...

journal_title：Medical physics

authors： Mera M,Pereira L,Mera M,Pereira L,Meilán E,Moral FD,Teijeiro A,Salgado M,Andrade B,Gomez F,Fuentes-Vázquez V,Caruncho J,Medina A

更新日期：2012-06-01 00:00:00

abstract：:We have recently installed a linear accelerator, modified to allow computer control of several machine parameters during irradiation of the patient. As an initial feasibility study of computer-controlled radiation therapy, its application to produce wedge-shaped dose distributions by moving the collimator jaws has bee...

journal_title：Medical physics

authors： Kijewski PK,Chin LM,Bjärngard BE

更新日期：1978-09-01 00:00:00

abstract：PURPOSE:To propose a method to calculate the tissue phantom ratio (TPR) using the depth dose and to compare the proposed method with two other methods. METHODS:An analytical dose model from Bjärngard was used to describe the depth dose and the TPR. The parameters of the model were derived from depth dose measurements,...

journal_title：Medical physics

authors： Ramos Garcia LI,Almansa JF

更新日期：2011-05-01 00:00:00

abstract：:In this report we evaluate an image registration technique that can improve the information content of intraoperative image data by deformable matching of preoperative images. In this study, pretreatment 1.5 tesla (T) magnetic resonance (MR) images of the prostate are registered with 0.5 T intraoperative images. The m...

journal_title：Medical physics

authors： Bharatha A,Hirose M,Hata N,Warfield SK,Ferrant M,Zou KH,Suarez-Santana E,Ruiz-Alzola J,D'Amico A,Cormack RA,Kikinis R,Jolesz FA,Tempany CM

更新日期：2001-12-01 00:00:00

abstract：:Coherent-scatter computed tomography (CSCT) is a novel imaging method we are developing to produce cross-sectional images based on the low-angle (<10 degrees) scatter properties of tissue. At diagnostic energies, this scatter is primarily coherent with properties dependent upon the molecular structure of the scatterer...

journal_title：Medical physics

authors： Batchelar DL,Cunningham IA

更新日期：2002-08-01 00:00:00

abstract：:Three Monte Carlo photon/electron transport codes (GEPTS, EGSnrc, and MCNP) are bench-marked against dose measurements in homogeneous (both low- and high-Z) media as well as at interfaces. A brief overview on physical models used by each code for photon and electron (positron) transport is given. Absolute calorimetric...

journal_title：Medical physics

authors： Chibani O,Li XA

更新日期：2002-05-01 00:00:00

abstract：PURPOSE:Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam-hard...

journal_title：Medical physics

authors： Shrock Z,Yoon SW,Gunasingha R,Oldham M,Adamson J

更新日期：2018-07-01 00:00:00

abstract：:A technique was developed to reduce the size and magnitude of the hot and cold spots in the abutting regions of photon and electron fields. The photon and electron fields were set up such that the photon field extended approximately 2 cm into the electron field in the abutting region. The region of the photon beam tha...

journal_title：Medical physics

authors： Li JG,Xing L,Boyer AL,Hamilton RJ,Spelbring DR,Turian JV

更新日期：1999-11-01 00:00:00

abstract：PURPOSE:The performance of a newly developed, high resolution, microangiographic fluoroscope (MAF) (35 μm pixel pitch and 300 μm thick CsI phosphor) was evaluated using a generalized linear system analysis and compared with that of a standard amorphous Si thin film transistor flat panel detector (FPD) (194 μm pixel pit...

journal_title：Medical physics

authors： Jain A,Bednarek DR,Rudin S

更新日期：2013-03-01 00:00:00

abstract：PURPOSE:To demonstrate the feasibility of a three-plenoptic camera projection, scintillation-based dosimetry system for measuring three-dimensional (3D) dose distributions of static photon radiation fields. METHODS:Static x-ray photon beams were delivered to a cubic plastic scintillator volume embedded within acrylic ...

journal_title：Medical physics

authors： Rilling M,Allain G,Thibault S,Archambault L

更新日期：2020-08-01 00:00:00

abstract：:A clamp-on current probe utilizing the Hall effect was used to determine x-ray tube current. This noninvasive technique was compared to two other methods of mA measurement: the Machlett Dynalyzer and the mR/mAs linearity method. Three diagnostic x-ray units were used in the comparison; two modern three-phase rooms and...

journal_title：Medical physics

authors： Atherton JV,Nickoloff EL

更新日期：1987-03-01 00:00:00

abstract：PURPOSE:The thermoluminescence dosimeter (TLD) has desirable features including low cost, reusability, small size, and relatively low energy dependence. However, the commonly available poly-crystal TLDs (e.g., TLD-100) exhibit high interdetector variability that requires individual calibration for high detection accura...

journal_title：Medical physics

authors： Shang D,Gu W,Landers A,Woods K,Yu V,Neph R,Tenn S,Sheng K

更新日期：2020-01-01 00:00:00

abstract：PURPOSE:To investigate tight-frame based iterative reconstruction (TFIR) technique for spectral breast computed tomography (CT) using fewer projections while achieving greater image quality. METHODS:The experimental data were acquired with a fan-beam breast CT system based on a cadmium zinc telluride photon-counting d...

journal_title：Medical physics

authors： Zhao B,Gao H,Ding H,Molloi S

更新日期：2013-03-01 00:00:00

abstract：PURPOSE:High-Z material in computed tomography (CT) yields metal artifacts that degrade image quality and may cause substantial errors in dose calculation. This study couples a metal artifact reduction (MAR) algorithm with enhanced 16-bit depth (vs standard 12-bit) to quantify potential gains in image quality and dosim...

journal_title：Medical physics

authors： Glide-Hurst C,Chen D,Zhong H,Chetty IJ

更新日期：2013-06-01 00:00:00

abstract：:A new factor for shifting isodoes curves for oblique Co-60 photon beams has been deduced. Like the two other known factors, this shift factor depends on the source-to-surface distance (SSD), the depth dose (D) and the derivative of D with depth. A comparison of corrected dose distributions has been made by using the t...

journal_title：Medical physics

authors： Iwasaki A,Ishito T

更新日期：1980-05-01 00:00:00

abstract：:Numerical reconstruction of x-ray spectra from narrow-beam transmission data was tested with published spectra in the range from 45 to 100 kVp. Transmission curves were calculated from the spectra to simulate measured data. Spectra were reconstructed from these transmission curves with use of an iterative numerical an...

journal_title：Medical physics

authors： Huang PH,Chen TS,Kase KR

更新日期：1986-09-01 00:00:00

abstract：PURPOSE:The hematopoietically active tissues of skeletal bone marrow are a prime target for computational dosimetry given potential risks of leukemia and, at higher dose levels, acute marrow toxicity. The complex three-dimensional geometry of trabecular spongiosa, however, complicates schema for dose assessment in such...

journal_title：Medical physics

authors： Geyer AM,Schwarz BC,Hobbs RF,Sgouros G,Bolch WE

更新日期：2017-01-01 00:00:00

abstract：PURPOSE:The aim of the study was to evaluate the impact of multileaf collimator (MLC) leaf width on treatment adaptation and delivery accuracy for concurrent treatment of the prostate and pelvic lymph nodes with intensity modulated radiation therapy (IMRT). METHODS:Seventy-five kilovoltage cone beam CTs (KV-CBCT) from...

journal_title：Medical physics

authors： Shang Q,Qi P,Ferjani S,Xia P

更新日期：2013-06-01 00:00:00

abstract：:The geometric accuracy and precision of an image-guided treatment system were assessed. Image guidance is performed using an x-ray volume imaging (XVI) system integrated with a linear accelerator and treatment planning system. Using an amorphous silicon detector and x-ray tube, volumetric computed tomography images ar...

journal_title：Medical physics

authors： Sharpe MB,Moseley DJ,Purdie TG,Islam M,Siewerdsen JH,Jaffray DA

更新日期：2006-01-01 00:00:00

abstract：PURPOSE:The quality of tomographic images is directly affected by the system model being used in image reconstruction. An accurate system matrix is desirable for high-resolution image reconstruction, but it often leads to high computation cost. In this work the authors present a maximum a posteriori reconstruction algo...

journal_title：Medical physics

authors： Fu L,Qi J

更新日期：2010-02-01 00:00:00

abstract：PURPOSE:Couch and MLC tracking are two promising methods for real-time motion compensation during radiation therapy. So far, couch and MLC tracking experiments have mainly been performed by different research groups, and no direct comparison of couch and MLC tracking of volumetric modulated arc therapy (VMAT) plans has...

journal_title：Medical physics

authors： Hansen R,Ravkilde T,Worm ES,Toftegaard J,Grau C,Macek K,Poulsen PR

更新日期：2016-05-01 00:00:00