Abstract：
:This paper describes the development and characterization of a fully automated in vitro cell irradiator using an electronic brachytherapy source to perform radiation sensitivity bioassays. This novel irradiator allows complex variable dose and dose rate schemes to be delivered to multiple wells of 96-well culture plates used in standard biological assays. The Xoft Axxent® eBx™ was chosen as the x-ray source due to its ability to vary tube current up to 300 µA for a 50 kVp spectrum using clinical surface applicators. Translation of the multiwell plate across the fixed radiation field is achieved using a precision motor driven computer controlled positioning system. A series of measurements was performed to characterize dosimetric performance of the system. Measurements have shown that the radiation output measured with an end window ionization chamber is stable between operating currents of 50-300 µA. In addition, radiochromic film was used to characterize the field flatness and symmetry. The average field flatness in the in-plane and cross-plane direction was 2.9 ± 1.0% and 4.0 ± 1.7%, respectively. The average symmetry in the in-plane and cross-plane direction was 1.8 ± 0.9% and 1.6 ± 0.5%, respectively. The optimal focal spot resolution at the cellular plane was determined by measuring sequential irradiations on radiochromic film for three different well spacing schemes. It was determined that the current system can irradiate every other well with negligible impact on the radiation field characteristics. Finally, a performance comparison between this system and a common cabinet irradiator is presented.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Fowler TL,Fulkerson RK,Micka JA,Kimple RJ,Bednarz BPdoi
10.1088/0031-9155/59/6/1459subject
Has Abstractpub_date
2014-03-21 00:00:00pages
1459-70issue
6eissn
0031-9155issn
1361-6560journal_volume
59pub_type
杂志文章abstract：:In magnetic drug targeting a chemotherapeutic agent is bound to coated magnetic nanoparticles, which are administered to the blood vessel system and subsequently focused by an external applied magnetic field. The optimization of intra-arterial magnetic drug targeting (MDT) requires detailed knowledge about the biodist...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/18/N03
更新日期：2009-09-21 00:00:00
abstract：:In this study, two computational phantoms of the newborn patient were used to assess individual organ doses and effective doses delivered during head, chest, abdomen, pelvis, and torso examinations using the Siemens SOMATOM Sensation 16 helical multi-slice computed tomography (MSCT) scanner. The stylized phantom used ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/20/005
更新日期：2006-10-21 00:00:00
abstract：:A calibration of the Fricke dosimeter is a measurement of epsilon G(Fe3+). Although G(Fe3+) is expected to be approximately energy independent for all low-LET radiation, existing data are not adequate to rule out the possibility of changes of a few per cent with beam quality. When a high-precision Fricke dosimeter, wh...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/44/7/303
更新日期：1999-07-01 00:00:00
abstract：:Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/14/019
更新日期：2007-07-21 00:00:00
abstract：:The degradation of low energy electrons in a methane based, tissue equivalent gas was studied experimentally by ionization chamber experiments and theoretically by Monte Carlo electron transport simulation in the energy range between 25 eV and 5 keV. From measured ionization yields and calculated ionization and energy...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/37/5/008
更新日期：1992-05-01 00:00:00
abstract：:The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the int...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/60/10/3959
更新日期：2015-05-21 00:00:00
abstract：:The beam quality correction factor k Q for megavoltage photon beams has been calculated for eight PTW (Freiburg, Germany) ionization chambers (Farmer chambers PTW30010, PTW30011, PTW30012, and PTW30013, Semiflex 3D chambers PTW31021, PTW31010, and PTW31013, and the PinPoint 3D chamber PTW31016). Simulations performed ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab9501
更新日期：2020-10-07 00:00:00
abstract：:In external beam radiation therapy, radioactive beams offer the best clinical solution to simultaneously treat and in vivo monitor the dose delivery and tumor response using PET or PET-CT imaging. However, difficulties mainly linked to the low production efficiency have so far limited their use. This study is devoted ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/6/005
更新日期：2011-03-21 00:00:00
abstract：:A computer program was developed to calculate both integral absorbed dose in a water phantom and entrance exposure, for the imaging of iodine contrast with x-ray intensifying screens. The effect of filtration of the x-ray beam on integral absorbed dose and entrance exposure was studied for 27 different filter material...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/31/6/001
更新日期：1986-06-01 00:00:00
abstract：:The relative biological effectiveness (RBE) of protons varies with multiple physical and biological factors. Phenomenological RBE models have been developed to include such factors in the estimation of a variable RBE, in contrast to the clinically applied constant RBE of 1.1. In this study, eleven published phenomenol...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aad9db
更新日期：2018-09-13 00:00:00
abstract：:Absorption and emission optical projection tomography (OPT), alternatively referred to as optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT), are recently developed three-dimensional imaging techniques with value for developmental biology and ex vivo gene expression studies...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/55/18/009
更新日期：2010-09-21 00:00:00
abstract：:A software program, SpekCalc, is presented for the calculation of x-ray spectra from tungsten anode x-ray tubes. SpekCalc was designed primarily for use in a medical physics context, for both research and education purposes, but may also be of interest to those working with x-ray tubes in industry. Noteworthy is the p...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/19/N01
更新日期：2009-10-07 00:00:00
abstract：:The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/59/9/2307
更新日期：2014-05-07 00:00:00
abstract：:Uncemented prosthetic joint implants used in orthopaedic surgery are usually coated with a porous surface to encourage bone ingrowth. Better contact between the endosteal bone and the porous surface improves ingrowth, and such contact may be increased if the joint further subsides into position in the first weeks foll...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/38/2/009
更新日期：1993-02-01 00:00:00
abstract：:An iterative algorithm has been developed to reduce blur artefacts in images obtained from the Pho/Con multiplane tomographic scanner. In this technique estimates of the activity distribution are convolved with the detector response function and compared with the original blurred image planes. Successive estimates of ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/30/7/004
更新日期：1985-07-01 00:00:00
abstract：:In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fr...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa9502
更新日期：2017-12-19 00:00:00
abstract：:Managing uncertainty is a major challenge in radiation therapy treatment planning, including uncertainty induced by intrafraction motion, which is particularly important for tumours in the thorax and abdomen. Common methods to account for motion are to introduce a margin or to convolve the static dose distribution wit...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/10/014
更新日期：2006-05-21 00:00:00
abstract：:The first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic prot...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/59/17/4961
更新日期：2014-09-07 00:00:00
abstract：:Delivery of pencil beam scanning (PBS) requires the on-line measurement of several beam parameters. If the measurement is outside of specified tolerances and a binary threshold algorithm is used, the beam will be paused. Given instrumentation and statistical noise such a system can lead to many pauses which could incr...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/61/1/400
更新日期：2016-01-07 00:00:00
abstract：:Exploiting the field response of magnetic tracers, magnetic particle imaging (MPI) allows direct, local quantification of the tracer concentration in bulk structures. Here, we investigated the use of characteristic field response functions to spatially resolve the absolute concentration of multiple nanoparticle specie...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/59/21/6521
更新日期：2014-11-07 00:00:00
abstract：:Ultra-wideband (UWB) electromagnetic pulses of nanosecond duration, or nanopulses, have recently been approved by the Federal Communications Commission for a number of different applications. They are also being explored for applications in biotechnology and medicine. The simulation of the propagation of a nanopulse t...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/50/21/007
更新日期：2005-11-07 00:00:00
abstract：:In a recent paper (Chamberland et al 2016 Phys. Med. Biol. 61 8214) develop a new Monte Carlo code called egs_brachy for brachytherapy treatments. It is based on EGSnrc, and written in the C++ programming language. In order to benchmark the egs_brachy code, the authors use it in various test case scenarios in which co...
journal_title：Physics in medicine and biology
pub_type： 评论,杂志文章,信件
doi：10.1088/1361-6560/aa9ea1
更新日期：2018-02-02 00:00:00
abstract：:A number of radiation-therapy-related uses based on a commercially available spreadsheet program have been developed at our facility. The graphics and display capabilities inherent in these spreadsheet programs allow for concise visual results. The spreadsheets are used as an independent check for several types of rad...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/40/6/007
更新日期：1995-06-01 00:00:00
abstract：:Indocyanine green (ICG) is a near-infrared dye that has the potential to be used as a tracer for the minimally invasive measurement of cerebral blood flow (CBF). In order to examine the technique, the arterial and cerebral concentrations of ICG were measured in newborn piglets during the bolus passage of ICG at normoc...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/46/8/312
更新日期：2001-08-01 00:00:00
abstract：:Modern digital radiographic 'flat panel' detectors can exhibit a progressive form of image degradation arising from non-functioning pixels. The effect of these 'dead pixels' on the quantitive image quality measures of modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE)...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/49/6/008
更新日期：2004-03-21 00:00:00
abstract：:Quantitative assessment of mammographic asymmetry has been investigated for breast cancer risk prediction. A new asymmetry feature extraction method was proposed in this study to enhance the risk prediction accuracy of near-term breast cancer. Breast areas in each pair of bilateral mammographic images were divided int...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aae452
更新日期：2018-10-17 00:00:00
abstract：:The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 × 10(5) B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 3...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/2/002
更新日期：2011-01-21 00:00:00
abstract：:All radiation therapy treatment planning relies on accurate dose calculation. Uncertainties in dosimetric prediction can significantly degrade an otherwise optimal plan. In this work, we introduce a robust optimization method which handles dosimetric errors and warrants for high-quality IMRT plans. Unlike other dose e...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/11/010
更新日期：2009-06-07 00:00:00
abstract：:A method to determine the spectrum of a clinical photon beam from measured depth-dose data is described. At shallow depths, where the range of Compton-generated electrons increases rapidly with photon energy, the depth dose provides the information to discriminate the spectral contributions. To minimize the influence ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/45/1/312
更新日期：2000-01-01 00:00:00
abstract：:It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid....
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/44/7/313
更新日期：1999-07-01 00:00:00
