Technical Note: Experimental determination of the effective point of measurement of two cylindrical ionization chambers in a clinical proton beam.

abstract：PURPOSE:To introduce video surface imaging guidance in synchronization with 4D cone-beam CT (CBCT) scans, and in combination with respiration- gated or target-tracked dose delivery to treat mobile tumors, without collaterally damaging nearby critical structures. METHODS:The approach uses the concept that the integral ...

journal_title：Medical physics

authors： Li S,Haiti B,Serratore D,Neicu T,Chan P,Valakh V,Bizhan M,Miyamoto C,Geng J

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficul...

journal_title：Medical physics

authors： Le Huy Q,Ducote JL,Molloi S

更新日期：2010-03-01 00:00:00

abstract：:A novel multistage algorithm is proposed for the automatic segmentation of microcalcification clusters (MCCs) in digital mammography. First, a previously reported tree structured nonlinear filter is proposed for suppressing image noise, while preserving image details, to potentially reduce the false positive (FP) dete...

journal_title：Medical physics

authors： Qian W,Kallergi M,Clarke LP,Li HD,Venugopal P,Song D,Clark RA

更新日期：1995-08-01 00:00:00

abstract：PURPOSE:The presence of respiratory motion during radiation treatment leads to degradation of the expected dose distribution, both for target coverage and healthy tissue sparing, particularly for techniques like pencil beam scanning proton therapy which have dynamic delivery systems. While tools exist to estimate this ...

journal_title：Medical physics

authors： Pepin MD,Tryggestad E,Wan Chan Tseung HS,Johnson JE,Herman MG,Beltran C

更新日期：2018-11-01 00:00:00

abstract：PURPOSE:In photon radiotherapy, respiratory-induced target motion can be accounted for by internal target volumes (ITV) or mid-ventilation target volumes (midV) defined on the basis of four-dimensional computed tomography (4D-CT). Intrinsic limitations of these approaches can result in target volumes that are not repre...

journal_title：Medical physics

authors： Rabe M,Thieke C,Düsberg M,Neppl S,Gerum S,Reiner M,Nicolay NH,Schlemmer HP,Debus J,Dinkel J,Landry G,Parodi K,Belka C,Kurz C,Kamp F

更新日期：2020-04-01 00:00:00

abstract：PURPOSE:The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI). METHODS:Time-sequenced b-mode...

journal_title：Medical physics

authors： Mostafaei F,Tai A,Gore E,Johnstone C,Haase W,Ehlers C,Cooper DT,Lachaine M,Li XA

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:To compare how the inclusion of the uncertainties in dose and optical density affects the results of the calibration of Gafchromic(®) EBT3 radiochromic films. METHODS:Five methods of least square minimization were compared for calibration of radiochromic films. These differed in the way in which the uncertaint...

journal_title：Medical physics

authors： Garcia LI,Azorin JF

更新日期：2013-07-01 00:00:00

abstract：:An in vitro radiographic technique which uses saline/iodine displacement has been developed to study the thickness of bone-equivalent and soft-tissue-equivalent materials within atherosclerotic plaques in arterial specimens which have been cut open longitudinally and laid flat. Results concerning the optimization of t...

journal_title：Medical physics

authors： Moreau M,Holdsworth DW,Fenster A

更新日期：1997-01-01 00:00:00

abstract：PURPOSE:Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper des...

journal_title：Medical physics

authors： Yun S,Tanguay J,Kim HK,Cunningham IA

更新日期：2013-04-01 00:00:00

abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...

journal_title：Medical physics

authors： Lewis D,Micke A,Yu X,Chan MF

更新日期：2012-10-01 00:00:00

abstract：:The purpose of this study is to perform a clinical evaluation of the first commercial (MDS Nordion, now Nucletron) treatment planning system for electron beams incorporating Monte Carlo dose calculation module. This software implements Kawrakow's VMC++ voxel-based Monte Carlo calculation algorithm. The accuracy of the...

journal_title：Medical physics

authors： Cygler JE,Daskalov GM,Chan GH,Ding GX

更新日期：2004-01-01 00:00:00

abstract：:Single-photon emission-computed tomography (SPECT) imaging of deep brain structures is compromised by loss of photons due to attenuation. We have previously shown that a centrally peaked collimator sensitivity function can compensate for this phenomenon, increasing sensitivity over most of the brain. For dual-head ins...

journal_title：Medical physics

authors： Park MA,Moore SC,Kijewski MF

更新日期：2005-07-01 00:00:00

abstract：PURPOSE:A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not. METHODS:In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validate...

journal_title：Medical physics

authors： Guo Z,Li L,Wang LV

更新日期：2009-09-01 00:00:00

abstract：:A nondestructive and noninvasive method for numeric characterization (quantification) of the structural composition of human bone tissue has been developed and tested. In order to quantify and to compare the structural composition of bones from 2D computed tomography (CT) images acquired at different skeletal location...

journal_title：Medical physics

authors： Saparin P,Thomsen JS,Kurths J,Beller G,Gowin W

更新日期：2006-10-01 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：:The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power sp...

journal_title：Medical physics

authors： Amendolia SR,Bisogni MG,Delogu P,Fantacci ME,Paternoster G,Rosso V,Stefanini A

更新日期：2009-04-01 00:00:00

abstract：:Depth dose characteristics of 24-MV beams from a medical linear accelerator at various SSDs have been measured. The dose buildup, percent depth dose (PDD), and output were measured using ionization chambers and a diode detector under full scatter. Surface dose ranged from 8% to 51% depending upon the collimator settin...

journal_title：Medical physics

authors： Jani SK,Pennington EC

更新日期：1991-03-01 00:00:00

abstract：:We describe a unique method that allows the comparison of spatially registered ultrasound (SRUS) images and computed tomography-derived contours (CTDCs) that were acquired with a minimal time lapse. As such, we have a tool that will provide validation of the spatial accuracy of the US system and that will allow compar...

journal_title：Medical physics

authors： Molloy JA,Srivastava S,Schneider BF

更新日期：2004-03-01 00:00:00

abstract：:The relatively precise placement of brachytherapy sources afforded by stereotactic frames for brain implants is not generally achievable for other sites, which lack the fixed geometry of the cranium and its contents. An exception is a source-containing rigid mold that delivers brachytherapy when inserted securely in a...

journal_title：Medical physics

authors： Anderson LL,Zlotolow IM,McCormick B,Harrison LB

更新日期：1995-03-01 00:00:00

abstract：:Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programm...

journal_title：Medical physics

authors： Yang S,Wang G,Skinner MW,Rubinstein JT,Vannier MW

更新日期：2000-04-01 00:00:00

abstract：:With the increased sophistication of lasers used for patient positioning in radiotherapy comes increased possibilities for mistakes in installing the lasers, which can result in serious patient positioning errors. Two principles must be followed when mounting cross-projecting lasers: (1) the horizontal line must be on...

journal_title：Medical physics

authors： Thomadsen BR

更新日期：1981-05-01 00:00:00

abstract：PURPOSE:Quantitative SPECT imaging is limited by many factors, including penetration of high energy photons through the collimator. Even small peaks of high energy yield extensive contamination in the photopeak energy window. Rotating slat collimators typically offer a 40- to 50-fold increase in geometric detection eff...

journal_title：Medical physics

authors： Van Holen R,Staelens S,Vandenberghe S

更新日期：2009-09-01 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：:Radiographic magnification is often employed in mammography to improve detection of small anatomical details of clinical interest, such as microcalcifications. The image size depends on the conventional magnification factor, on the focal spot size, and on the x-ray angulation. In this paper magnification effects are i...

journal_title：Medical physics

authors： Schiabel H,Ventura A,Frère AF

更新日期：1994-02-01 00:00:00

abstract：:In intensity modulated radiation treatments (IMRT), the position of the field edges and the modulation within the beam are often achieved with a multileaf collimator (MLC). During the MLC calibration process, due to the finite accuracy of leaf position measurements, a systematic error may be introduced to leaf positio...

journal_title：Medical physics

authors： Parent L,Seco J,Evans PM,Dance DR,Fielding A

更新日期：2006-09-01 00:00:00

abstract：PURPOSE:The purpose of the study is to investigate the characteristics of a two-dimensional (2D) liquid-filled ion chamber detector array, which is used for the verification of radiotherapy treatment plans that use small field sizes of up to 10 × 10 cm. METHODS:The device used in this study was Octavius 1000 SRS model...

journal_title：Medical physics

authors： Markovic M,Stathakis S,Mavroidis P,Jurkovic IA,Papanikolaou N

更新日期：2014-05-01 00:00:00

abstract：PURPOSE:A prototype in-house program was developed to assist deriving image guidance shifts clinically using our 4DCT method for lung SBRT. METHODS:Our in-house prototype program was implemented in MATLAB. The 4D DICOM CT dataset of interest is imported by the program from AW and subsequently accepts input from the us...

journal_title：Medical physics

authors： Wang B,Sarkar V,Busselberg C,Rassiah-Szegedi P,Zhao H,Huang Y,Szegedi M,Salter B

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:Adding magnetic resonance (MR)-derived information to standard transrectal ultrasound (TRUS) images for guiding prostate biopsy is of substantial clinical interest. A tumor visible on MR images can be projected on ultrasound (US) by using MR-US registration. A common approach is to use surface-based registratio...

journal_title：Medical physics

authors： van de Ven WJ,Hu Y,Barentsz JO,Karssemeijer N,Barratt D,Huisman HJ

更新日期：2015-05-01 00:00:00

abstract：PURPOSE:A radiophotoluminescent glass rod dosimeter (RGD) has recently become commercially available. It is being increasingly used for dosimetry in radiotherapy to measure the absorbed dose including scattered low-energy photons on the body surface of a patient and for postal dosimetry audit. In this article, the dosi...

journal_title：Medical physics

authors： Kadoya N,Shimomura K,Kitou S,Shiota Y,Fujita Y,Dobashi S,Takeda K,Jingu K,Matsushita H,Namito Y,Ban S,Koyama S,Tabushi K

更新日期：2012-10-01 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