Dual-energy x-ray projection imaging: two sampling schemes for the correction of scattered radiation.

abstract：PURPOSE:Stereotactic ablative body radiotherapy (SABR) for lung patients can be performed with volumetric-modulated arc therapy (VMAT) plans using off-axis target geometry to allow treatment in their CBCT verified position. For patient-specific quality assurance measurements using the PTW Octavius 4D phantom (PTW, Frei...

journal_title：Medical physics

authors： Jeevanandam P,Agnew CE,Irvine DM,McGarry CK

更新日期：2018-04-01 00:00:00

abstract：PURPOSE:For the purpose of size-specific dose estimation, information regarding patient attenuation is required. The purpose of this work is to describe a method for measuring patient attenuation and expressing the results in terms of a water cylinder, with cross sectional area A(w), which would absorb the same average...

journal_title：Medical physics

authors： Wang J,Duan X,Christner JA,Leng S,Yu L,McCollough CH

更新日期：2012-11-01 00:00:00

abstract：PURPOSE:Photon counting arrays (PCAs), capable of measuring the spectral information of individual x-ray photons and recording that information digitally, provide a number of advantages compared to conventional, energy-integrating active matrix flat-panel imagers - such as reducing the undesirable effects of electronic...

journal_title：Medical physics

authors： Liang AK,Koniczek M,Antonuk LE,El-Mohri Y,Zhao Q

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:Lower radiation tolerance of the whole liver hinders dose escalations of stereotactic body radiation therapy (SBRT) in hepatocellular carcinoma (HCC) treatment. This study was conducted to define the exact doses that result in radiation-induced liver disease (RILD) as well as to determine dose constraints for t...

journal_title：Medical physics

authors： Wu ZF,Zhang JY,Shen XY,Zhou LY,Gao YB,Hu Y,Zeng ZC

更新日期：2016-07-01 00:00:00

abstract：PURPOSE:In this abstract, we discuss a biomechanical head and neck model that will be able to represent patient setup variations as well as physiologic changes and subsequently enable dose calculations on the deformed anatomy. METHODS:We selected Multi Pose MRI as the imaging modality to aid in model development and v...

journal_title：Medical physics

authors： Santhanam A,Ennis D,Low D,Kupelian P

更新日期：2012-06-01 00:00:00

abstract：:This paper examines the distributions of the SAR (specific absorption rate) ratio and temperature elevation when an ultrasound beam propagates through the interface of muscle and bone. This interface is regarded as a flat boundary to partition the energy of the ultrasound beam, and the analytical solution of temperatu...

journal_title：Medical physics

authors： Lin WL,Liauh CT,Chen YY,Liu HC,Shieh MJ

更新日期：2000-05-01 00:00:00

abstract：:Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (...

journal_title：Medical physics

authors： Raylman RR,Majewski S,Wojcik R,Weisenberger AG,Kross B,Popov V,Bishop HA

更新日期：2000-08-01 00:00:00

abstract：PURPOSE:The main objective of this work was to design a comprehensive dosimetry package that would keep all aspects of internal dose calculation within the framework of a single software environment and that would be applicable for a variety of dose calculation approaches. METHODS:Our MATLAB-based graphical user inter...

journal_title：Medical physics

authors： Grimes J,Uribe C,Celler A

更新日期：2013-07-01 00:00:00

abstract：:The concept of equivalent uniform dose (EUD) has been suggested as a means to quantitatively consider heterogeneous dose distributions within targets. Tumor cell density/function is typically assumed to be uniform. We herein propose to use 18F-labeled 2-deoxyglucose (FDG) positron emission tomography (PET) tumor imagi...

journal_title：Medical physics

authors： Zhou SM,Wong TZ,Marks LB

更新日期：2004-09-01 00:00:00

abstract：:DICOM format is the de facto standard for communications between therapeutic and diagnostic modalities. A plan generated by a treatment planning system (TPS) is often exported to DICOM format. BEAMnrc/DOSXYZnrc is a widely used Monte Carlo (MC) package for beam and dose simulations in radiotherapy. It has its own defi...

journal_title：Medical physics

authors： Zhan L,Jiang R,Osei EK

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:Temporal subtraction is used to detect the interval change in chest radiographs and aid radiologists in patient diagnosis. This method registers two temporally different images by geometrically warping the lung region, or "lung mask," of a previous radiographic image to align with the current image. The gray le...

journal_title：Medical physics

authors： Armato SG 3rd,Sensakovic WF,Passen SJ,Engelmann R,MacMahon H

更新日期：2009-12-01 00:00:00

abstract：:Head-scatter factors of symmetric square and rectangular fields (field center on the central beam axis) defined by the upper (Y) and lower (X) jaws for 6 and 15 MV photon beams from 2300CD and 600C accelerators (Varian Associates, Inc., Palo Alto, CA) were measured, as well as those for fields shaped by the Y jaws and...

journal_title：Medical physics

authors： Yu MK,Murray B,Sloboda R

更新日期：1995-08-01 00:00:00

abstract：PURPOSE:To demonstrate the ultra-high resolution capability of a small field-of-view (FOV) solid state x-ray imaging detector based on an EMCCD sensor. METHODS:A micro-solid state x-ray image intensifier (micro-SSXII) was developed to serve as an ultra-high resolution region-of-interest (ROI) imaging detector. It is b...

journal_title：Medical physics

authors： Singh V,Loughran B,Jain A,Sharma P,Bednarek D,Rudin S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. METHODS:The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Co...

journal_title：Medical physics

authors： Simon TA,Kahler D,Simon WE,Fox C,Li J,Palta J,Liu C

更新日期：2009-10-01 00:00:00

abstract：PURPOSE:Two ultra-high-resolution (UHR) computed tomography (CT) scanners are clinically available. One is achieved by a CT system with a 0.25 mm × 160 row detector (Detector-UHR), whereas the other is with a 0.6 mm × 32 row detector with in-plane comb filtering in a dual source CT (Comb-UHR). We compared radiation dos...

journal_title：Medical physics

authors： Kawashima H,Ichikawa K,Takata T,Nagata H,Hoshika M,Akagi N

更新日期：2020-02-01 00:00:00

abstract：:The observation of scattered radiations of larger wavelength than the primary had been repeatedly rejected or explained away by many researchers, including Compton. After years of vacillations, he recognized the effect named after him and was the first to develop a quantal equation predicting the wavelength of scatter...

journal_title：Medical physics

authors： del Regato JA

更新日期：1981-11-01 00:00:00

abstract：:Atomic Energy of Canada Limited 60Co teletherapy units have adjustable collimator hinges to adapt to source diameters from 0.75 to 2.50 cm. Adjustment of the collimator hinge to the manfacturer's settings can cause a loss of radiation field flatness as high as 20% for large fields. The recommended settings appear to c...

journal_title：Medical physics

authors： Heintz PH

更新日期：1975-03-01 00:00:00

abstract：:Recently, new imaging modalities based on the detection of weak phase perturbations effects, among which are phase contrast and diffraction imaging, have been developed by several researchers. Due to their high sensitivity to weakly absorbing details, these techniques seem to be very promising for applications in the ...

journal_title：Medical physics

authors： Olivo A,Arfelli F,Cantatore G,Longo R,Menk RH,Pani S,Prest M,Poropat P,Rigon L,Tromba G,Vallazza E,Castelli E

更新日期：2001-08-01 00:00:00

abstract：:The purpose of this paper is to develop a method that reduces the number of segments for intensity modulated arc therapy (IMAT) and intensity modulated radiotherapy (IMRT) for concave target volumes (TV). The aim was to utilize no more than two intensity levels per organ at risk (OAR) and to derive both optimal segmen...

journal_title：Medical physics

authors： Bratengeier K

更新日期：2005-03-01 00:00:00

abstract：PURPOSE:To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. METHODS:A PET-...

journal_title：Medical physics

authors： Thomas CM,Pike LC,Hartill CE,Baker S,Woods E,Convery DJ,Greener AG

更新日期：2014-04-01 00:00:00

abstract：PURPOSE:To automatically detect and isolate areas of low and high stiffness temporal stability in shear wave elastography (SWE) image sequences and define their impact in chronic liver disease (CLD) diagnosis improvement by means of clinical examination study and deep learning algorithm employing convolutional neural n...

journal_title：Medical physics

authors： Gatos I,Tsantis S,Spiliopoulos S,Karnabatidis D,Theotokas I,Zoumpoulis P,Loupas T,Hazle JD,Kagadis GC

更新日期：2019-05-01 00:00:00

abstract：OBJECTIVES:To evaluate the performance of RapidArc® (Eclipse 10.0.28) and SmartArc® (Pinnacle 9.0) radiotherapy plans for lung stereotactic body radiation therapy (SBRT) in terms of dosimetric plan quality, delivery efficiency, inhomogeneity corrections and accuracy of dose delivery using a custom-built heterogeneity i...

journal_title：Medical physics

authors： Fakir H,Hoover D,Chen JZ

更新日期：2012-07-01 00:00:00

abstract：:Many problems in physics involve imaging objects with high spatial frequency content in a limited amount of time. The limitation of available experimental data leads to the infamous problem of diffraction limited data which manifests itself by causing ringing in the image. This ringing is due to the interference pheno...

journal_title：Medical physics

authors： Haacke EM,Liang ZP,Izen SH

更新日期：1989-05-01 00:00:00

abstract：:The objective of this work was to create a comprehensive online tool to evaluate and review the performance of quality assurance measurements that assess beam output and profile constancy as soon as they are acquired using statistical process control. As part of routine quality assurance: output, flatness and symmetry...

journal_title：Medical physics

authors： Chmielewski R,Abbas A,Yeung I

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:The authors previously introduced a methodology to generate a realistic three-dimensional (3D), high-resolution, computer-simulated breast phantom based on empirical data. One of the key components of such a phantom is that it provides a means to produce a realistic simulation of clinical breast compression. In...

journal_title：Medical physics

authors： Hsu CM,Palmeri ML,Segars WP,Veress AI,Dobbins JT 3rd

更新日期：2011-10-01 00:00:00

abstract：PURPOSE:To correct for the deviations of the detector response when typical radiation detectors are used under non-reference conditions, factor kNR was calculated from the known energy dependence of the detector response at photon energies from 10 keV upwards and from clinical photon spectra within a large water phanto...

journal_title：Medical physics

authors： Chofor N,Poppe B,Harder D

更新日期：2012-06-01 00:00:00

abstract：:Ultrasound contrast agents consist of microscopically small encapsulated bubbles that oscillate upon insonification. To enhance diagnostic ultrasound imaging techniques and to explore therapeutic applications, these medical microbubbles have been studied with the aid of high-speed photography. We filmed medical microb...

journal_title：Medical physics

authors： Postema M,van Wamel A,ten Cate FJ,de Jong N

更新日期：2005-12-01 00:00:00

abstract：PURPOSE:Secondary particles produced in the collision of protons with beam modifiers are of concern in proton therapy. Nevertheless, secondary radiation can provide information on the dosimetric parameters through its dependency on the modulating accessories (range shifter and range modulating wheel). Relatively little...

journal_title：Medical physics

authors： Carnicer A,Letellier V,Rucka G,Angellier G,Sauerwein W,Herault J

更新日期：2012-12-01 00:00:00

abstract：PURPOSE:Computer-aided diagnosis (CAD) systems assist in solving subjective diagnosis problems that typically rely on personal experience. A CAD system has been developed to differentiate malignant thyroid nodules from benign thyroid nodules in ultrasound images based on deep learning methods. The diagnostic performanc...

journal_title：Medical physics

authors： Sun C,Zhang Y,Chang Q,Liu T,Zhang S,Wang X,Guo Q,Yao J,Sun W,Niu L

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:The segmentation accuracy of medical images was improved by increasing the number of training samples using a local image warping technique. The performance of the proposed method was evaluated in the segmentation of breast masses, prostate and brain tumors, and lung nodules. METHODS:We propose a simple data a...

journal_title：Medical physics

authors： Liu H,Cao H,Song E,Ma G,Xu X,Jin R,Liu T,Liu L,Liu D,Hung CC

更新日期：2020-12-10 00:00:00