Spacing nomograph for interstitial implants of 125I seeds.

abstract：PURPOSE:The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease stat...

journal_title：Medical physics

authors： Ambrico M,Lasalvia M,Ligonzo T,Ambrico PF,Perna G,Capozzi V

更新日期：2020-10-01 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：:The goal of this study was to develop a technique to distinguish benign and malignant breast lesions in secondarily digitized mammograms. A set of 51 mammograms (two views/patient) containing lesions of known pathology were evaluated using six different morphological descriptors: circularity, mu R/sigma R (where mu R ...

journal_title：Medical physics

authors： Pohlman S,Powell KA,Obuchowski NA,Chilcote WA,Grundfest-Broniatowski S

更新日期：1996-08-01 00:00:00

abstract：:Conventional IMRT dose verification using film and ion chamber measurements is useful but limited with respect to the actual dose distribution received by the patient. The Monte Carlo simulation has been introduced as an independent dose verification tool for IMRT using the patient CT data and MLC leaf sequence files,...

journal_title：Medical physics

authors： Luo W,Li J,Price RA Jr,Chen L,Yang J,Fan J,Chen Z,McNeeley S,Xu X,Ma CM

更新日期：2006-07-01 00:00:00

abstract：:Accurately assessing the quality of prostate brachytherapy intraoperatively would be valuable for improved clinical outcome by ensuring the delivery of a prescribed tumoricidal radiation dose to the entire prostate gland. One necessary step towards this goal is the robust and rapid localization of implanted seeds. Sev...

journal_title：Medical physics

authors： Tutar IB,Managuli R,Shamdasani V,Cho PS,Pathak SD,Kim Y

更新日期：2003-12-01 00:00:00

abstract：:A contrast-detail (CD) experiment was performed to study the effect of lossy compression on computed radiographic (CR) images. Digital CR images of a phantom were compressed by quantizing the full-frame discrete cosine transform and Huffman encoding the result. Since low-contrast detectability is directly linked to an...

journal_title：Medical physics

authors： Cook LT,Insana MF,McFadden MA,Hall TJ,Cox GG

更新日期：1995-06-01 00:00:00

abstract：:The half-life of two I-125 encapsulated clinical seeds was measured with a Si(Li) semiconductor detector. Two measurements of each seed yielded an average half-life of 59.56 +/- 0.17 days. The results are discussed in terms of the influence of possible I-126 contamination and leakage of I-125 activity through encapsul...

journal_title：Medical physics

authors： Kubo H

更新日期：1983-11-01 00:00:00

abstract：:In the presence of intrafraction organ motion, target localization uncertainty can greatly hamper the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT). To minimize the adverse dosimetric effect caused by tumor motion, a real-time knowledge of the tumor position is requ...

journal_title：Medical physics

authors： Wiersma RD,Mao W,Xing L

更新日期：2008-04-01 00:00:00

abstract：PURPOSE:Computerized liver extraction from hepatic CT images is challenging because the liver often abuts other organs of a similar density. The purpose of this study was to develop a computer-aided measurement of liver volumes in hepatic CT. METHODS:The authors developed a computerized liver extraction scheme based o...

journal_title：Medical physics

authors： Suzuki K,Kohlbrenner R,Epstein ML,Obajuluwa AM,Xu J,Hori M

更新日期：2010-05-01 00:00:00

abstract：PURPOSE:Coronary x-ray computed tomography angiography (CCTA) is used to non-invasively assess coronary artery geometry and has, combined with computational modeling, demonstrated the potential to identify physiologically significant lesions. These measurements require robust and accurate coronary imaging and delineati...

journal_title：Medical physics

authors： Contijoch F,Stayman JW,McVeigh ER

更新日期：2017-07-01 00:00:00

abstract：:The effectiveness of film-screen mammography is limited by tradeoffs between latitude and contrast, film granularity, and the need to increase dose when antiscatter methods are used. We are currently developing a scanned-projection digital mammography (SPDM) system to overcome these limitations. The system consists of...

journal_title：Medical physics

authors： Nishikawa RM,Mawdsley GE,Fenster A,Yaffe MJ

更新日期：1987-09-01 00:00:00

abstract：:A formalism for an independent dose verification of the Gamma Knife treatment planning is developed. It is based on the approximation that isodose distribution for a single shot is in the shape of an ellipsoid in three-dimensional space. The dose profiles for a phantom along each of the three major axes are fitted to ...

journal_title：Medical physics

authors： Phaisangittisakul N,Ma L

更新日期：2002-09-01 00:00:00

abstract：PURPOSE:Computed tomography (CT) and, in particular, cone beam CT (CBCT) have been increasingly used as a diagnostic tool in recent years. Patient motion during acquisition is common in CBCT due to long scan times. This results in degraded image quality and may potentially increase the number of retakes. Our aim was to...

journal_title：Medical physics

authors： Niebler S,Schömer E,Tjaden H,Schwanecke U,Schulze R

更新日期：2019-10-01 00:00:00

abstract：:Modulation of the activity of the subthalamic nucleus (STN) using deep brain stimulation (DBS) in patients with advanced Parkinson's disease is the most common procedure performed today by functional neurosurgeons. The STN contours cannot be entirely identified on common 1.5 T images; in particular, the ventromedial b...

journal_title：Medical physics

authors： Stancanello J,Muacevic A,Sebastiano F,Modugno N,Cerveri P,Ferrigno G,Uggeri F,Romanelli P

更新日期：2008-07-01 00:00:00

abstract：:An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic imag...

journal_title：Medical physics

authors： Zhao W,Li D,Reznik A,Lui BJ,Hunt DC,Rowlands JA,Ohkawa Y,Tanioka K

更新日期：2005-09-01 00:00:00

abstract：:As a quality control procedure, a post-implant seed migration survey has been accomplished on 340 prostate cancer patients since November 2001. Pulmonary seed embolization and intracardiac seed embolization have been detected. A case of thyroid uptake due to leaking iodine-125 (I-125) sources was also seized. In order...

journal_title：Medical physics

authors： Chen QS,Russell JL Jr,Macklis RR,Weinhous MS,Blair HF

更新日期：2006-07-01 00:00:00

abstract：:Transmission imaging is receiving increasing attention in SPECT due to the need to compensate for nonuniform attenuation in cardiac-chest SPECT. The quality of a transmission image has an important effect on the measured attenuation distribution. To improve image quality, knowledge of the performance characteristics o...

journal_title：Medical physics

authors： Cao Z,Tsui BM

更新日期：1992-09-01 00:00:00

abstract：PURPOSE:The management of thoracic malignancies with radiation therapy is complicated by continuous target motion. In this study, a real time motion analysis approach is proposed to improve the accuracy of patient setup. METHODS:For 11 lung cancer patients a long training fluoroscopy was acquired before the first trea...

journal_title：Medical physics

authors： Chen T,Jabbour SK,Qin S,Haffty BG,Yue N

更新日期：2013-04-01 00:00:00

abstract：:The focal spot of a linear accelerator is often considered to have a fully stable position. In practice, however, the beam control loop of a linear accelerator needs to stabilize after the beam is turned on. As a result, some motion of the focal spot might occur during the start-up phase of irradiation. When acquiring...

journal_title：Medical physics

authors： Sonke JJ,Brand B,van Herk M

更新日期：2003-06-01 00:00:00

abstract：PURPOSE:Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravi...

journal_title：Medical physics

authors： Keuschnigg P,Kellner D,Fritscher K,Zechner A,Mayer U,Huber P,Sedlmayer F,Deutschmann H,Steininger P

更新日期：2017-01-01 00:00:00

abstract：PURPOSE:Intensity modulated proton therapy (IMPT) is sensitive to errors, mainly due to high stopping power dependency and steep beam dose gradients. Conventional margins are often insufficient to ensure robustness of treatment plans. In this article, a method is developed that takes the uncertainties into account duri...

journal_title：Medical physics

authors： Fredriksson A,Forsgren A,Hårdemark B

更新日期：2011-03-01 00:00:00

abstract：:We report on some extensions and further developments of a well-known microcalcification detection algorithm based on adaptive noise equalization. Tissue equivalent phantom images with and without labeled microcalcifications were subjected to this algorithm, and analyses of results revealed some shortcomings in the ap...

journal_title：Medical physics

authors： Gürün OO,Fatouros PP,Kuhn GM,de Paredes ES

更新日期：2001-04-01 00:00:00

abstract：:Current dosimetry protocols for clinical protons do not take into account any secondary electron fluence perturbation in ion chambers. In this work, we performed a systematic study of secondary electron fluence perturbation factors for spherical and cylindrical ion chambers in proton beams (70-250 MeV). The electron f...

journal_title：Medical physics

authors： Verhaegen F,Palmans H

更新日期：2001-10-01 00:00:00

abstract：:Receiver operating characteristic (ROC) methodology is widely used in evaluating medical imaging modalities. While appropriate in some cases, it has several drawbacks when the detection task, e.g., nodule detection, involves localizing the abnormality. Free-response receiver operating characteristic (FROC) methodology...

journal_title：Medical physics

authors： Chakraborty DP

更新日期：1989-07-01 00:00:00

abstract：:Secondary neutron ambient dose equivalents per the treatment absorbed dose in passive carbon-ion and proton radiotherapies were measured using a rem meter, WENDI-II at two carbon-ion radiotherapy facilities and four proton radiotherapy facilities in Japan. Our measured results showed that (1) neutron ambient dose equi...

journal_title：Medical physics

authors： Yonai S,Matsufuji N,Kanai T,Matsui Y,Matsushita K,Yamashita H,Numano M,Sakae T,Terunuma T,Nishio T,Kohno R,Akagi T

更新日期：2008-11-01 00:00:00

abstract：PURPOSE:In the practice code of dosimetry, humidity effect is assumed to be constant as far as the measurements are performed in the relative humidity (RH) range of (20-80)%; thus, the humidity effect can be ignored with a dose uncertainty of 0.15%. This assumption is based on the previous experimental results by Niate...

journal_title：Medical physics

authors： Sato Y,Shimizu M,Morishita Y,Sato M,Hoshina M

更新日期：2019-09-01 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:Motion compensated positron emission tomography (PET) imaging requires detecting and monitoring of patient body motion. We developed a semiautomatic list-mode method to track the three-dimensional (3D) motion of fiducial positron-emitting markers during PET imaging. METHODS:A previously developed motion tracki...

journal_title：Medical physics

authors： Chamberland MJP,deKemp RA,Xu T

更新日期：2020-08-01 00:00:00

abstract：:In the last 30 years, thousands of basic or clinical studies have been devoted to atherosclerosis or to the problem of restenosis after angioplasty. In these studies, axial stresses in the vessel wall have received practically no attention, contrary to circumferential stress and purely biological aspects. Based on a r...

journal_title：Medical physics

authors： Doriot PA,Dorsaz PA

更新日期：2005-02-01 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