Abstract：
:In a recent paper of Miller et al. (Med. Phys. 43(5), 2141-2152 (2016), the voltage dependence polarity effect of microionization chambers was studied. It was identified that polarity effect arises from the difference in electric potential between the collecting electrode and the guard electrode, which in turn deforms the electric field and affects the charge collection. Nevertheless, the cause of such potential difference has not been identified. In this letter, we explain that the electric potential perturbation arises from the work function difference of the disparate materials electrodes (collecting vs guard electrodes in the particular case).
journal_name
Med Physjournal_title
Medical physicsauthors
Brivio D,Sajo E,Zygmanski Pdoi
10.1002/mp.12019subject
Has Abstractpub_date
2017-03-01 00:00:00pages
1204-1205issue
3eissn
0094-2405issn
2473-4209journal_volume
44pub_type
信件相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:A multi-institution dosimetry intercomparison has been undertaken of prostate intensity modulated radiation therapy (IMRT) delivery. The dosimetry intercomparison was incorporated into the quality assurance for site credentialing for the Trans-Tasman Radiation Oncology Group Prostate Fractionated Irradiation Tr...
journal_title：Medical physics
pub_type： 临床试验,杂志文章,多中心研究
doi：10.1118/1.4808151
更新日期：2013-07-01 00:00:00
abstract：:We believe that, for the purpose of evaluation and optimization of treatment plans, quasirandom sampling is superior to grid sampling and should be the method of choice. We believe it to be on average more efficient than grid sampling (i.e., more accurate for any given number of dose estimates) and, even more importan...
journal_title：Medical physics
pub_type： 评论,信件
doi：10.1118/1.597103
更新日期：1993-09-01 00:00:00
abstract：PURPOSE:The aim of this research was to explore x-ray beam parameters with intent to optimize pediatric x-ray settings in the cardiac catheterization laboratory. This study examined the effects of peak x-ray tube voltage (kVp) and of copper (Cu) x-ray beam filtration independently on the image quality to dose balance f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3488911
更新日期：2010-10-01 00:00:00
abstract：PURPOSE:The purpose of this study was to investigate the impact of transverse magnetic fields on the dose response of a radiophotoluminescent glass dosimeter (RGD) in megavoltage photon beams. METHODS:The RGD relative response (i.e., RGD dose per absorbed dose to water at the midpoint of the detector in the absence of...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14054
更新日期：2020-04-01 00:00:00
abstract：:An investigation was performed of the changes in image quality and patient dose as a result of increasing filtration for fluoroscopy performed under automatic brightness control. Filtration was added either at the x-ray tube housing (i.e., scatter-free geometry) or adjacent to a tissue equivalent phantom simulating th...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597906
更新日期：1997-03-01 00:00:00
abstract：PURPOSE:The authors had previously published measurements of the detectability of disk-shaped contrast objects in images obtained from a C-arm CT system. A simple approach based on Rose's criterion was used to scale the date, assuming the threshold for the smallest diameter detected should be inversely proportional to ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3397465
更新日期：2010-05-01 00:00:00
abstract：:We have developed a new method for optimization in intensity modulated radiation therapy (IMRT) that makes use of simulated dynamics in a classical system of interacting particles. An analogy is drawn between intensity profile optimization in IMRT and relaxation to the equilibrium configuration in a dynamic system. Th...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1528179
更新日期：2003-01-01 00:00:00
abstract：PURPOSE:An improved method of image guidance for lung tumor biopsies could help reduce the high rate of false negatives. The aim of this work is to optimize the geometry of the scanning-beam digital tomography system (SBDX) for providing real-time 3D tomographic reconstructions for target verification. The unique geome...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4826159
更新日期：2013-11-01 00:00:00
abstract：:System modeling is used to investigate the effect of various system parameters on the image quality in CCD-based x-ray imaging systems. The systems considered consist of a typical phosphor-based scintillating screen coupled to a CCD through lens or fiberoptic taper. Two applications, chest radiography and mammography,...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598072
更新日期：1997-02-01 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
pub_type： 杂志文章,评审
doi：10.1118/1.4935141
更新日期：2015-12-01 00:00:00
abstract：PURPOSE:Our aim was to compare different magnet arrangements for magnetic cell delivery to human lower leg arteries and investigate the theoretical targeting efficiency under realistic flow conditions as a possible treatment after angioplasty. Additionally the potential of scaling down or translating the magnetic actua...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3593363
更新日期：2011-07-01 00:00:00
abstract：PURPOSE:Researchers write many computer programs with unique implementations, usually requiring a great amount of effort for other researchers to learn how to install, configure, and use. Some programs require specialized hardware platforms such as GPU workstation or CPU cluster, which may not readily available for man...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735274
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4739195
更新日期：2012-09-01 00:00:00
abstract：PURPOSE:Effective dose (ED) is a widely used metric for comparing ionizing radiation burden between different imaging modalities, scanners, and scan protocols. In computed tomography (CT), ED can be estimated by performing scans on an anthropomorphic phantom in which metal-oxide-semiconductor field-effect transistor (M...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4868693
更新日期：2014-04-01 00:00:00
abstract：:The validity of conclusions drawn from multi-institutional radiotherapy studies is dependent upon the degree to which participating hospitals adhere to study requirements. A major effort undertaken by the Quality Assurance Review Center (QARC) assesses whether or not patient data which are deemed evaluable actually co...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595221
更新日期：1982-03-01 00:00:00
abstract：PURPOSE:Imaging biomarkers are crucial in managing treatment options for cancer patients. They are extremely powerful tools since they allow personalized treatment assessment early during therapy by using repeated imaging to detect and quantify tumor response. Currently, treatment response assessment from consecutive i...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4764900
更新日期：2013-01-01 00:00:00
abstract：PURPOSE:To develop a new biological equivalent dose (BED) formulism that includes repair, repopulation and resensitization (redistribution and reoxygenation), and can be used to calculate prescribed dose for permanent implant with Cs-131. METHODS:Because of lack of sufficient clinical data, the prescribed dose with ne...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735551
更新日期：2012-06-01 00:00:00
abstract：:Reported MOSFET measurements concern mostly external radiotherapy and in vivo dosimetry. In this paper, we apply the technique for absolute dosimetry in the context of HDR brachytherapy using an 192Ir source. Measured radial dose rate distributions in water for different planes perpendicular to the source axis are pre...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2198168
更新日期：2006-06-01 00:00:00
abstract：:A four-parameter Laplace transform pair model, which accurately reconstructs an experimental bremsstrahlung spectrum from attenuation data, is presented. Computed spectral values with both aluminum and copper attenuators generally agree with experimental 70-kVp data to better than 2%. Reconstructed spectra at other kV...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595193
更新日期：1982-11-01 00:00:00
abstract：PURPOSE:We propose a new metric called Distance Discordance (DD), which is defined as the distance between two anatomic points from two moving images, which are co-located on some reference image, when deformed onto another reference image. METHODS:To demonstrate the concept of DD, we created a reference software phan...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4736139
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Plastic scintillation detectors are used for dosimetry in small radiation fields with high dose gradients, e.g., provided by β-emitting sources like 106 Ru/106 Rh eye plaques. A drawback is a background signal caused by Cerenkov radiation generated by electrons passing the optical fibers (light guides) of this ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12374
更新日期：2017-09-01 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
pub_type： 杂志文章
doi：10.1002/mp.12033
更新日期：2017-01-01 00:00:00
abstract：:Modern radiotherapy linacs often use carbon fibre for their couch tops due to its radio translucent properties. Beam attenuation by the couches is often ignored during planning and MU calculation. This work examines beam attenuation and loss of "skin sparing" (dose build up region) when various photon beams transit ei...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2965951
更新日期：2008-07-01 00:00:00
abstract：:Using superior localization and immobilization methods, stereotactic radiosurgery is capable of delivering spheres of dose as small as a few millimetres in diameter to intracranial targets. For targets abutting critical structures, the most conformal treatments minimize adverse radiation side effects and it is importa...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2965910
更新日期：2008-07-01 00:00:00
abstract：PURPOSE:Transrectal ultrasound (TRUS)-guided needle biopsy is the current gold standard for prostate cancer diagnosis. However, up to 40% of prostate cancer lesions appears isoechoic on TRUS. Hence, TRUS-guided biopsy has a high false negative rate for prostate cancer diagnosis. Magnetic resonance imaging (MRI) is bett...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4905104
更新日期：2015-03-01 00:00:00
abstract：PURPOSE:This work introduces a rigid registration framework for patient positioning in radiotherapy, based on real-time surface acquisition by a time-of-flight (ToF) camera. Dynamic properties of the system are also investigated for future gating/tracking strategies. METHODS:A novel preregistration algorithm, based on...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3664006
更新日期：2012-01-01 00:00:00
abstract：:This paper presents a numerical investigation of the effective point of measurement of thimble ionization chambers in megavoltage photon beams using Monte Carlo simulations with the EGSNRC system. It is shown that the effective point of measurement for relative photon beam dosimetry depends on every detail of the cham...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2201147
更新日期：2006-06-01 00:00:00
abstract：PURPOSE:Although robot-assisted coronary artery bypass grafting (RA-CABG) has gained more acceptance worldwide, its success still depends on the surgeon's experience and expertise, and the conversion rate to full sternotomy is in the order of 15%-25%. One of the reasons for conversion is poor pre-operative planning, wh...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3684958
更新日期：2012-03-01 00:00:00
abstract：:Bioluminescent imaging (BLI) of luciferase-expressing cells in live small animals is a powerful technique for investigating tumor growth, metastasis, and specific biological molecular events. Three-dimensional imaging would greatly enhance applications in biomedicine since light emitting cell populations could be unam...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2138007
更新日期：2006-01-01 00:00:00
abstract：PURPOSE:The purpose of this study is to investigate some characteristics of the beam delivery system and their effects on the dose distribution of intensity-modulated radiation therapy (IMRT) and the results of patient-specific IMRT quality assurance (QA). These characteristics include the accelerator source distributi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3413997
更新日期：2010-06-01 00:00:00
