Parametrization of head-scatter factors for rectangular photon fields using an equivalent square formalism.

abstract：:Optimal visualization of moving structures such as the heart and coronary arteries using digital radiographic imaging systems is a difficult problem that can involve tradeoffs between temporal, spatial, and density resolution. The motion dependence of four angiographic measures of vessel dimensions is given and demons...

journal_title：Medical physics

authors： Parker DL,Clayton PD,Gustafson DE

更新日期：1985-11-01 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：:Total body photon irradiation (TBI) may be delivered with a number of standard techniques, typically using extended SSD geometries to obtain large field sizes. Since 1982 we have treated over 620 patients (adult and pediatric) mostly in the floor-located prone/supine treatment position with AP/PA beams using a column ...

journal_title：Medical physics

authors： Evans M,Ruo R,Seuntjens J,Freeman CR,Parker W

更新日期：2012-07-01 00:00:00

abstract：:A multislit collimator was designed and fabricated for basic studies on microbeam radiation therapy (MRT) with an x-ray energy of about 100 keV. It consists of 30 slits that are 25 microm high, 30 mm wide, and 5 mm thick in the beam direction. The slits were made of 25 microm-thick polyimide sheets that were separated...

journal_title：Medical physics

authors： Ohno Y,Torikoshi M,Suzuki M,Umetani K,Imai Y,Uesugi K,Yagi N

更新日期：2008-07-01 00:00:00

abstract：PURPOSE:For almost four decades bead and wire ramps have been used in the evaluation of slice width as part of QA testing for CT scanners. While each of these approaches have been recognized and accepted as reliable, in this paper we investigate the differences, advantages and limitations of these tools. Moreover, we s...

journal_title：Medical physics

authors： Marteinsdóttir M,Olafsdottir H,Fredriksson J,Andresson A,Healy A,Kristbjornsson A,Kristinsson S,Levy J,Goodenough D

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately ...

journal_title：Medical physics

authors： Lu B,Smallwood AM,Sellers TA,Drukteinis JS,Heine JJ,Fowler EE

更新日期：2015-02-01 00:00:00

abstract：:By design, the range of beam directions in conventional radiosurgery are constrained to an isocentric array. However, the recent introduction of robotic radiosurgery dramatically increases the flexibility of targeting, and as a consequence, beams need be neither coplanar nor isocentric. Such a nonisocentric design per...

journal_title：Medical physics

authors： Schweikard A,Schlaefer A,Adler JR Jr

更新日期：2006-11-01 00:00:00

abstract：PURPOSE:The number of pencil beam scanned proton therapy (PBS-PT) facilities equipped with cone-beam computed tomography (CBCT) imaging treating thoracic indications is constantly rising. To enable daily internal motion monitoring during PBS-PT treatments of thoracic tumors, we assess the performance of Motion-Aware Re...

journal_title：Medical physics

authors： den Otter LA,Chen K,Janssens G,Meijers A,Both S,Langendijk JA,Rosen LR,Wu HT,Knopf AC

更新日期：2020-12-01 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：:Ultrasound has been the greatest imaging modality worldwide for many years by equipment purchase value and by number of machines and examinations. It is becoming increasingly the front end imaging modality; serving often as an extension of the physician's fingers. We believe that at the other extreme, high-end systems...

journal_title：Medical physics

authors： Carson PL,Fenster A

更新日期：2009-02-01 00:00:00

abstract：:Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which wome...

journal_title：Medical physics

authors： Ng KH,Lau S

更新日期：2015-12-01 00:00:00

abstract：PURPOSE:Over the last four decades, Ocular Proton Therapy has been successfully used to treat patients affected by intraocular lesions. For this, treatment geometry verification is routinely performed using radiographic images to align a configuration of fiducial radiopaque markers implanted on the sclera outer surface...

journal_title：Medical physics

authors： Via R,Hennings F,Fattori G,Fassi A,Pica A,Lomax A,Weber DC,Baroni G,Hrbacek J

更新日期：2018-05-01 00:00:00

abstract：PURPOSE:To design a fast Winston Lutz (fWL) algorithm for accurate analysis of radiation isocenter from images without edge detection or center of mass calculations. METHODS:An algorithm has been developed to implement the Winston Lutz test for mechanical/ radiation isocenter agreement using an electronic portal imagi...

journal_title：Medical physics

authors： Winey B,Sharp G,Bussière M

更新日期：2011-01-01 00:00:00

abstract：:A comparison of two methods of scatter compensation in single photon emission computed tomography (SPECT) imaging is made on the basis of improvements in quantification. The methods, scatter-window subtraction and constrained deconvolution of an average point source response function (PSRF), are described; the theoret...

journal_title：Medical physics

authors： Yanch JC,Flower MA,Webb S

更新日期：1990-11-01 00:00:00

abstract：PURPOSE:The objective of this study was to evaluate organ dose and the effective dose to patients undergoing tomosynthesis (TS) and C-arm cone-beam computed tomography (CBCT) examinations and to compare the doses to those in multidetector CT (MDCT) scans. METHODS:Patient doses were measured with small sized silicon-ph...

journal_title：Medical physics

authors： Koyama S,Aoyama T,Oda N,Yamauchi-Kawaura C

更新日期：2010-08-01 00:00:00

abstract：:Various radionuclides have been proposed for systemic tumor therapy. However, in most dosimetric analysis of proposed radionuclides the charged particles are taken into consideration while the potential photons are ignored. The photons will cause undesirable irradiation of normal tissue, and increase the probability o...

journal_title：Medical physics

authors： Uusijärvi H,Bernhardt P,Ericsson T,Forssell-Aronsson E

更新日期：2006-09-01 00:00:00

abstract：PURPOSE:At our institution, all proton patient plans undergo patient-specific quality assurance (PSQA) prior to treatment delivery. For intensity-modulated proton beam therapy, quality assurance is complex and time consuming, and it may involve multiple measurements per field. We reviewed our PSQA workflow and identifi...

journal_title：Medical physics

authors： Hernandez Morales D,Shan J,Liu W,Augustine KE,Bues M,Davis MJ,Fatyga M,Johnson JE,Mundy DW,Shen J,Younkin JE,Stoker JB

更新日期：2019-01-01 00:00:00

abstract：:Intensity modulated radiation therapy (IMRT) with a dynamic multileaf collimator (DMLC) requires synchronization of DMLC leaf motion with dose delivery. A delay in DMLC communication is known to cause leaf lag and lead to dosimetric errors. The errors may be exacerbated by gated operation. The purpose of this study wa...

journal_title：Medical physics

authors： Duan J,Shen S,Fiveash JB,Brezovich IA,Popple RA,Pareek PN

更新日期：2003-08-01 00:00:00

abstract：PURPOSE:The automated segmentation of each lung and trachea in CT scans is commonly taken as a solved problem. Indeed, existing approaches may easily fail in the presence of some abnormalities caused by a disease, trauma, or previous surgery. For robustness, we present ALTIS (implementation is available at http://lids....

journal_title：Medical physics

authors： Sousa AM,Martins SB,Falcão AX,Reis F,Bagatin E,Irion K

更新日期：2019-11-01 00:00:00

abstract：PURPOSE:To experimentally commission a dual-energy CT (DECT) joint statistical image reconstruction (JSIR) method, which is built on a linear basis vector model (BVM) of material characterization, for proton stopping power ratio (SPR) estimation. METHODS:The JSIR-BVM method builds on the relationship between the energ...

journal_title：Medical physics

authors： Zhang S,Han D,Williamson JF,Zhao T,Politte DG,Whiting BR,O'Sullivan JA

更新日期：2019-01-01 00:00:00

abstract：PURPOSE:Many biological objects, including neuronal dendrites, blood vasculature, airways, phylogenetic trees, produce tree structured data. Current methods of analysis either ignore the complex structure of trees or use distance-based methods which limit the scope of multivariate modeling. METHODS:We propose a branch...

journal_title：Medical physics

authors： Roy Choudhury K,Skwerer S

更新日期：2018-03-01 00:00:00

abstract：:The synchronization of dynamic multileaf collimator (DMLC) response with respiratory motion is critical to ensure the accuracy of DMLC-based four dimensional (4D) radiation delivery. In practice, however, a finite time delay (response time) between the acquisition of tumor position and multileaf collimator response ne...

journal_title：Medical physics

authors： Vedam S,Docef A,Fix M,Murphy M,Keall P

更新日期：2005-06-01 00:00:00

abstract：PURPOSE:To compare beam characteristics of superficial X-rays with 6 MeV Electrons for the purpose of replacing superficial treatments with electron fields for skin lesions. METHODS:Electron beam cutouts were made with 12mm thickness cerrobend in diameters 2-5 cm to match superficial X-ray machine cones. Central axis ...

journal_title：Medical physics

authors： Avadhani J,Sasidharan S,Carton C,Lowen M,Klapproth T,Licitra C

更新日期：2012-06-01 00:00:00

abstract：:We are evaluating the usefulness of stereomammography in improving breast cancer diagnosis. One area that we are investigating is whether the improved depth perception associated with stereomammography might be significantly enhanced with the use of a virtual 3D cursor. A study was performed to evaluate the accuracy o...

journal_title：Medical physics

authors： Goodsitt MM,Chan HP,Hadjiiski L

更新日期：2000-06-01 00:00:00

abstract：PURPOSE:The purpose of this study is to investigate whether the microvascular pseudodiffusion effects resulting with non-monoexponential behavior are present in breast cancer, taking into account tumor spatial heterogeneity. Additionally, methodological factors affecting the signal in low and high diffusion-sensitizing...

journal_title：Medical physics

authors： Panek R,Borri M,Orton M,O'Flynn E,Morgan V,Giles SL,deSouza N,Leach MO,Schmidt MA

更新日期：2015-08-01 00:00:00

abstract：PURPOSE:Currently, no 3D or 4D volumetric x-ray imaging techniques are available for intrafraction verification of target position during actual treatment delivery or in-between treatment beams, which is critical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. This study a...

journal_title：Medical physics

authors： Ren L,Zhang Y,Yin FF

更新日期：2014-02-01 00:00:00

abstract：PURPOSE:The paper presents a complete computer-aided detection (CAD) system for the detection of lung nodules in computed tomography images. A new mixed feature selection and classification methodology is applied for the first time on a difficult medical image analysis problem. METHODS:The CAD system was trained and t...

journal_title：Medical physics

authors： Tan M,Deklerck R,Jansen B,Bister M,Cornelis J

更新日期：2011-10-01 00:00:00

abstract：:In patients with lymphoma, identification and quantification of the tumor extent on serial CT examinations is critical for assessing tumor response to therapy. In this paper, we present a computer method to automatically match and segment lymphomas in follow-up CT images. The method requires that target lymph nodes in...

journal_title：Medical physics

authors： Yan J,Zhao B,Curran S,Zelenetz A,Schwartz LH

更新日期：2007-01-01 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

abstract：PURPOSE:Polymer-based gel dosimeter (MAGIC type) is a preferable phantom material for PET range verification of proton beam therapy. However, improvement in elemental tissue equivalency (specifically O/C ratio) is very desirable to ensure realistic time-activity measurements. METHODS:Glucose and urea was added to the ...

journal_title：Medical physics

authors： Zhu X,Reese TG,Crowley EM,El Fakhri G

更新日期：2010-01-01 00:00:00