abstract：PURPOSE:Statistical modeling of an ultrasound backscattered echo envelope is used for tissue characterization. However, in the presence of complex structures within the analyzed area, estimation of parameters is disturbed and unreliable, e.g., in the case of breast tumor classification. In order to improve the differen...

journal_title：Medical physics

authors： Byra M,Nowicki A,Wróblewska-Piotrzkowska H,Dobruch-Sobczak K

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:The purpose of this technical note is to introduce variance component analysis to the estimation of systematic and random components in setup error of radiotherapy. METHODS:Balanced data according to the one-factor random effect model were assumed. RESULTS:Analysis-of-variance (anova)-based computation was ap...

journal_title：Medical physics

authors： Matsuo Y,Nakamura M,Mizowaki T,Hiraoka M

更新日期：2016-09-01 00:00:00

abstract：PURPOSE:To develop a practical background compensation (BC) technique to improve quantitative (90)Y-bremsstrahlung single-photon emission computed tomography (SPECT)/computed tomography (CT) using a commercially available imaging system. METHODS:All images were acquired using medium-energy collimation in six energy wi...

journal_title：Medical physics

authors： Siman W,Mikell JK,Kappadath SC

更新日期：2016-09-01 00:00:00

abstract：PURPOSE:To investigate the use of local noise power spectrum (NPS) to characterize image noise and wavelet analysis to isolate defective pixels and inter-subpanel flat-fielding artifacts for quantitative quality assurance (QA) of electronic portal imaging devices (EPIDs). METHODS:A total of 93 image sets including cus...

journal_title：Medical physics

authors： Lee S,Yan G,Bassett P,Gopal A,Samant S

更新日期：2016-09-01 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:To estimate and correct for the volume averaging effect which results from the intra-chamber dose gradients when a Farmer ionization chamber (IC) is used for reference dosimetry in flattening-filter-free (FFF) MV photon beams. METHODS:An intra-chamber dose gradients correction factor (kicdg) to the charge read...

journal_title：Medical physics

authors： Ruggieri R,Naccarato S,Stavrev P,Stavreva N,Pasetto S,Salamone I,Alongi F

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:Magnetic resonance imaging (MRI) is increasingly used for radiotherapy target delineation, image guidance, and treatment response monitoring. Recent studies have shown that an entire external x-ray radiotherapy treatment planning (RTP) workflow for brain tumor or prostate cancer patients based only on MRI refer...

journal_title：Medical physics

authors： Koivula L,Wee L,Korhonen J

更新日期：2016-08-01 00:00:00

abstract：PURPOSE:The image quality of dedicated cone beam breast CT (CBBCT) is limited by substantial scatter contamination, resulting in cupping artifacts and contrast-loss in reconstructed images. Such effects obscure the visibility of soft-tissue lesions and calcifications, which hinders breast cancer detection and diagnosis...

journal_title：Medical physics

authors： Shi L,Vedantham S,Karellas A,Zhu L

更新日期：2016-08-01 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：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：:The increasing complexity of modern radiation therapy planning and delivery challenges traditional prescriptive quality management (QM) methods, such as many of those included in guidelines published by organizations such as the AAPM, ASTRO, ACR, ESTRO, and IAEA. These prescriptive guidelines have traditionally focuse...

journal_title：Medical physics

authors： Huq MS,Fraass BA,Dunscombe PB,Gibbons JP Jr,Ibbott GS,Mundt AJ,Mutic S,Palta JR,Rath F,Thomadsen BR,Williamson JF,Yorke ED

更新日期：2016-07-01 00:00:00

abstract：PURPOSE:Wide-angle free-air chambers (WAFACs) are used as primary standard measurement devices for establishing the air-kerma strength of low-energy, low-dose rate brachytherapy seeds. The National Research Council of Canada (NRC) is commissioning a primary standard wide-angle free-air chamber (NRC WAFAC) to serve the ...

journal_title：Medical physics

authors： Shen H,Culberson WS,Ross CK

更新日期：2016-07-01 00:00:00

abstract：PURPOSE:The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor. METHODS:The authors ...

journal_title：Medical physics

authors： Badano A,Wang J,Boynton P,Le Callet P,Cheng WC,Deroo D,Flynn MJ,Matsui T,Penczek J,Revie C,Samei E,Steven PM,Swiderski S,Van Hoey G,Yamaguchi M,Hasegawa M,Nagy BV

更新日期：2016-07-01 00:00:00

abstract：:Surgical guidance with fluorescence has been demonstrated in individual clinical trials for decades, but the scientific and commercial conditions exist today for a dramatic increase in clinical value. In the past decade, increased use of indocyanine green based visualization of vascular flow, biliary function, and tis...

journal_title：Medical physics

authors： Pogue BW,Paulsen KD,Samkoe KS,Elliott JT,Hasan T,Strong TV,Draney DR,Feldwisch J

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:Metal artifact reduction (MAR) is a major problem and a challenging issue in x-ray computed tomography (CT) examinations. Iterative reconstruction from sinograms unaffected by metals shows promising potential in detail recovery. This reconstruction has been the subject of much research in recent years. However,...

journal_title：Medical physics

authors： Zhang H,Wang L,Li L,Cai A,Hu G,Yan B

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:Pulmonary magnetic-resonance-imaging (MRI) and x-ray computed-tomography have provided strong evidence of spatially and temporally persistent lung structure-function abnormalities in asthmatics. This has generated a shift in their understanding of lung disease and supports the use of imaging biomarkers as inter...

journal_title：Medical physics

authors： Guo F,Svenningsen S,Eddy RL,Capaldi DPI,Sheikh K,Fenster A,Parraga G

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:Automated detection of solitary pulmonary nodules using positron emission tomography (PET) and computed tomography (CT) images shows good sensitivity; however, it is difficult to detect nodules in contact with normal organs, and additional efforts are needed so that the number of false positives (FPs) can be fu...

journal_title：Medical physics

authors： Teramoto A,Fujita H,Yamamuro O,Tamaki T

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scin...

journal_title：Medical physics

authors： Larsson JC,Lundström U,Hertz HM

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:An improvement in tissue assignment for low-dose rate brachytherapy (LDRB) patients using more accurate Monte Carlo (MC) dose calculation was accomplished with a metallic artifact reduction (MAR) method specific to dual-energy computed tomography (DECT). METHODS:The proposed MAR algorithm followed a four-step ...

journal_title：Medical physics

authors： Côté N,Bedwani S,Carrier JF

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:The aim of this study was to implement a Dirichlet process mixture (DPM) model for automatic tumor edge identification on (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) images by optimizing the parameters on which the algorithm depends, to validate it experimentally, and to test its robus...

journal_title：Medical physics

authors： Giri MG,Cavedon C,Mazzarotto R,Ferdeghini M

更新日期：2016-05-01 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

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：PURPOSE:Incorporating training into image segmentation is a good approach to achieve additional robustness. This work aims to develop an effective strategy to utilize shape prior knowledge, so that the segmentation label evolution can be driven toward the desired global optimum. METHODS:In the variational image segmen...

journal_title：Medical physics

authors： Zhao T,Ruan D

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:To investigate the geometry dependence of the detector response function (DRF) of three commonly used scanning ionization chambers and its impact on a convolution-based method to address the volume averaging effect (VAE). METHODS:A convolution-based approach has been proposed recently to address the ionization...

journal_title：Medical physics

authors： Barraclough B,Li JG,Lebron S,Fan Q,Liu C,Yan G

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed...

journal_title：Medical physics

authors： Humbert L,Hazrati Marangalou J,Del Río Barquero LM,van Lenthe GH,van Rietbergen B

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:Patient motion is a common problem during dynamic positron emission tomography (PET) scans for quantification of myocardial blood flow (MBF). The purpose of this study was to quantify the prevalence of body motion in a clinical setting and evaluate with realistic phantoms the effects of motion on blood flow qua...

journal_title：Medical physics

authors： Hunter CR,Klein R,Beanlands RS,deKemp RA

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:Radiation scattered from the breast in digital breast tomosynthesis (DBT) causes image degradation, including loss of contrast between cancerous and background tissue. Unlike in 2-dimensional (2D) mammography, an antiscatter grid cannot readily be used in DBT because changing alignment between the tube and dete...

journal_title：Medical physics

authors： Patel T,Peppard H,Williams MB

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:Different approaches have been used in dynamic elastography to assess mechanical properties of biological tissues. Most techniques are based on a simple inversion based on the measurement of the shear wave speed to assess elasticity, whereas some recent strategies use more elaborated analytical or finite elemen...

journal_title：Medical physics

authors： Ouared A,Kazemirad S,Montagnon E,Cloutier G

更新日期：2016-04-01 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：PURPOSE:To find an upper bound on the maximum dose reduction possible for any reconstruction algorithm, analytic or iterative, that result from the inclusion of the data statistics. The authors do not analyze noise reduction possible from prior knowledge or assumptions about the object. METHODS:The authors examined th...

journal_title：Medical physics

authors： Hsieh SS,Chesler DA,Fleischmann D,Pelc NJ

更新日期：2016-03-01 00:00:00

abstract：PURPOSE:A compact, three-tesla magnetic resonance imaging (MRI) system has been developed. It features a 37 cm patient aperture, allowing the use of commercial receiver coils. Its design allows simultaneously for gradient amplitudes of 85 millitesla per meter (mT/m) sustained and 700 tesla per meter per second (T/m/s) ...

journal_title：Medical physics

authors： Weavers PT,Shu Y,Tao S,Huston J 3rd,Lee SK,Graziani D,Mathieu JB,Trzasko JD,Foo TK,Bernstein MA

更新日期：2016-03-01 00:00:00

abstract：:Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing nov...

journal_title：Medical physics

authors： Mehranian A,Arabi H,Zaidi H

更新日期：2016-03-01 00:00:00

abstract：PURPOSE:It is important for many quantitative brain studies to label meaningful anatomical regions in MR brain images. However, due to high complexity of brain structures and ambiguous boundaries between different anatomical regions, the anatomical labeling of MR brain images is still quite a challenging task. In many ...

journal_title：Medical physics

authors： Ma G,Gao Y,Wu G,Wu L,Shen D

更新日期：2016-02-01 00:00:00

abstract：PURPOSE:This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and geant4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. METHODS:A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within th...

journal_title：Medical physics

authors： Ahmad SB,Sarfehnia A,Paudel MR,Kim A,Hissoiny S,Sahgal A,Keller B

更新日期：2016-02-01 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:Proton computed tomography (pCT) will enable accurate prediction of proton and ion range in a patient while providing the benefit of lower radiation exposure than in x-ray CT. The accuracy of the range prediction is essential for treatment planning in proton or ion therapy and depends upon the detector used to ...

journal_title：Medical physics

authors： Bashkirov VA,Schulte RW,Hurley RF,Johnson RP,Sadrozinski HF,Zatserklyaniy A,Plautz T,Giacometti V

更新日期：2016-02-01 00:00:00

abstract：PURPOSE:This work investigates the energy response and dose-response curve determinations for XR-QA2 radiochromic film dosimetry system used for synchrotron radiation work and for quality assurance in diagnostic radiology, in the range of effective energies 18-46.5 keV. METHODS:Pieces of XR-QA2 films were irradiated, ...

journal_title：Medical physics

authors： Di Lillo F,Mettivier G,Sarno A,Tromba G,Tomic N,Devic S,Russo P

更新日期：2016-01-01 00:00:00

abstract：PURPOSE:The objectives of this study were (a) to devise a technique for measuring quantum noise in clinical body computed tomography (CT) images and (b) to develop a model for predicting that noise with high accuracy. METHODS:The study included 83 clinical image sets at two dose levels (clinical and 50% reduced dose l...

journal_title：Medical physics

authors： Tian X,Samei E

更新日期：2016-01-01 00:00:00

abstract：PURPOSE:To report on significant dose enhancement effects caused by magnetic fields aligned parallel to 6 MV photon beam radiotherapy of small lung tumors. Findings are applicable to future inline MRI-guided radiotherapy systems. METHODS:A total of eight clinical lung tumor cases were recalculated using Monte Carlo me...

journal_title：Medical physics

authors： Oborn BM,Ge Y,Hardcastle N,Metcalfe PE,Keall PJ

更新日期：2016-01-01 00:00:00

abstract：PURPOSE:A preobject grid can reduce and correct scatter in cone beam computed tomography (CBCT). However, half of the signal in each projection is blocked by the grid. A synchronized moving grid (SMOG) has been proposed to acquire two complimentary projections at each gantry position and merge them into one complete pr...

journal_title：Medical physics

authors： Zhang H,Ren L,Kong V,Giles W,Zhang Y,Jin JY

更新日期：2016-01-01 00:00:00