Abstract:
:New x-ray radiographic systems based on large-area flat-panel technology have revolutionized our capability to produce digital x-ray images. However, these imagers are extraordinarily expensive compared to the systems they are replacing. Hence, there is a need for a low-cost digital imaging system for general applications in radiology. A novel potentially low-cost radiographic imaging system based on established technologies is proposed-the X-Ray Light Valve (XLV). This is a potentially high-quality digital x-ray detector made of a photoconducting layer and a liquid-crystal cell, physically coupled in a sandwich structure. Upon exposure to x rays, charge is collected on the surface of the photoconductor. This causes a change in the optical properties of the liquid-crystal cell and a visible image is generated. Subsequently, it is digitized by a scanned optical imager. The image formation is based on controlled modulation of light from an external source. The operation and practical implementation of the XLV system are described. The potential performance of the complete system and issues related to sensitivity, spatial resolution, noise, and speed are discussed. The feasibility of clinical use of an XLV device based on amorphous selenium (a-Se) as the photoconductor and a reflective electrically controlled birefringence cell is analyzed. The results of our analysis indicate that the XLV can potentially be adapted to a wide variety of radiographic tasks.
journal_name
Med Physjournal_title
Medical physicsauthors
Webster CA,Koprinarov I,Germann S,Rowlands JAdoi
10.1118/1.2837288subject
Has Abstractpub_date
2008-03-01 00:00:00pages
939-49issue
3eissn
0094-2405issn
2473-4209journal_volume
35pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:to use complementary cine EPID and gimbals log file analysis for in-vivo tracking accuracy monitoring. METHODS:A clinical prototype of dynamic tracking (DT) was installed on the Vero SBRT system. This prototype version allowed tumor tracking by gimballed linac rotations using an internal-external correspondenc...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736204
更新日期:2012-06-01 00:00:00
abstract::In a series of in vivo experiments on five adult canines, a small cylindrical permanent magnet (approximately 5-mm diameter x 5 mm long) was magnetically moved under fluoroscopic guidance from an occipital-lobe burr hole to a predetermined destination within the brain and then removed. On three of the animals, dorsal ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596520
更新日期:1990-05-01 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
pub_type: 杂志文章
doi:10.1118/1.597489
更新日期:1995-06-01 00:00:00
abstract::In Monte Carlo simulations of light transport in tissues, a grid system is set up to score physical quantities. This study of cylindrically symmetrical problems found that the optimized radial and angular positions for the averaged physical quantities in each grid element are off-center. The error of the extrapolated ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597351
更新日期:1994-07-01 00:00:00
abstract:PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12110
更新日期:2017-03-01 00:00:00
abstract:PURPOSE:A 3-year project called LABSYNC has been recently funded by the European Commission, with the aim of designing a radiation facility based on a compact light source, i.e., a laboratory-sized commercial synchrotron, capable of accelerating electrons up to 6 or 20 MeV. An accurate spectral description of hard x ra...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3223357
更新日期:2009-10-01 00:00:00
abstract:PURPOSE:TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12672
更新日期:2018-01-01 00:00:00
abstract::A new energy selective detector for dual energy computed radiography has been developed that combines many of the advantages of x-ray tube voltage switching and single exposure double screen detectors. The new active detector utilizes electro-optical modulation of the response of the storage phosphor screens to allow ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597831
更新日期:1996-10-01 00:00:00
abstract:PURPOSE:To build a statistical model to quantitatively correlate the anatomic features of structures and the corresponding dose-volume histogram (DVH) of head and neck (HN) Tomotherapy (Tomo) plans. To study if the model built upon one intensity modulated radiation therapy (IMRT) technique (such as conventional Linac) ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4828788
更新日期:2013-12-01 00:00:00
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...
journal_title:Medical physics
pub_type: 信件
doi:10.1002/mp.12019
更新日期:2017-03-01 00:00:00
abstract::Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597412
更新日期:1994-10-01 00:00:00
abstract:PURPOSE:Low-dose CT has attracted increasing attention due to growing concerns about radiation exposure in medical scans. However, the frugal use of x-ray radiation inevitably reduces the quality of the CT images, introducing artifacts such as noise and streaks which make the reconstructed images difficult to read in c...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736528
更新日期:2012-08-01 00:00:00
abstract:PURPOSE:Linac-magnetic resonance (MR) systems have been proposed in order to achieve realtime image guided radiotherapy. The design of a new linac-MR system with the in-line 6 MV linac generating x-rays along the symmetry axis of an open MR imager is outlined. This new design allows for a greater MR field strength to a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3481513
更新日期:2010-09-01 00:00:00
abstract::A simple noninvasive method is described for determining the backscatter to a monitor chamber of a medical accelerator based on the measurement of charge deposited in the target. This method is compared quantitatively to the more elaborate telescopic method for photon beams of 6 MV and 15 MV on linear accelerators hav...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598203
更新日期:1998-03-01 00:00:00
abstract:PURPOSE:To evaluate the replacement of Cerrobend by copper for electron beam cutouts. METHODS:The dosimetric comparisons for circular copper-and Cerrobend-cutouts with diameters (1.0, 2.0, 3.0, 5.0, 7.5, 10.0, and 12.5 cm) were made using electron beams with energies (6, 9, 12, 16, and 20 MeV) from 3 Varian accelerato...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735336
更新日期:2012-06-01 00:00:00
abstract::Two experimental methods are described for obtaining average energies of neutron spectra produced by an electron accelerator in a medical treatment room. In the first method, the dose equivalent is measured by means of indium activation foils in an Andersson-Braun moderator. Fluences are determined by the usual activa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595662
更新日期:1985-11-01 00:00:00
abstract::One of the methods currently being used to treat choroidal melanoma employs an episcleral plaque containing I-125 radioactive seeds. However, comprehensive dosimetry studies on the plaque are scarce and controversial. For this work, we use film to study the dosimetry outside the lip of the gold shield of the eye plaqu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596556
更新日期:1990-09-01 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:To study and compare the dose response curves of the new GafChromic EBT3 film for megavoltage and kilovoltage x-ray beams, with different spatial resolution. METHODS:Two sets of EBT3 films (lot#A101711-02) were exposed to each x-ray beam (6MV, 15MV and 50kV) at 8 dose values (50-3200cGy). The megavoltage beams...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735153
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Development and verification of peak signal-to-noise ratio (SNR(P)) equations for determining optimum CT scanning and scoring parameters for a new automated coronary calcium scoring program (N-vivo). Experimental evaluation of the new program for scoring small calcium hydroxyapatite (CaHA) microspheres with sma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3442276
更新日期:2010-07-01 00:00:00
abstract::The use of dedicated magnetic resonance simulation (MR-SIM) platforms in Radiation Oncology has expanded rapidly, introducing new equipment and functionality with the overall goal of improving the accuracy of radiation treatment planning. However, this emerging technology presents a new set of challenges that need to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14695
更新日期:2021-01-01 00:00:00
abstract:PURPOSE:The purpose of the present study was to perform an analysis of the changes in the dynamic seroma cavity based on fiducial markers in early stage breast cancer patients treated with accelerated partial breast irradiation (APBI) using three-dimensional conformal external beam radiotherapy (3D-CRT). METHODS:A pro...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4788644
更新日期:2013-02-01 00:00:00
abstract:PURPOSE:The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides exce...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914860
更新日期:2015-04-01 00:00:00
abstract:PURPOSE:The purpose of this paper was to present a method of determining the dose profile of the beam bow-tie filter (BTF) without the need for fixing the x ray tube in a position or using special instruments or dosimeters other than the ordinary types of ion chambers used for CT dosimetry (e.g., Farmer chamber). METH...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13203
更新日期:2018-11-01 00:00:00
abstract:PURPOSE:With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) IMAT solution. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3622672
更新日期:2011-09-01 00:00:00
abstract::An integrating solid-state dosimeter has been developed to detect ultraviolet radiation using the process of "direct" ultraviolet stimulation. This process yields a thermoluminescent signal after an exposure to ultraviolet radiation, without prior exposure to ionizing radiation. Magnesium oxide crystals were found to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594259
更新日期:1976-11-01 00:00:00
abstract:PURPOSE:To evaluate the treatment planning system (TPS) performance of the ZAP-X stereotactic radiosurgery (SRS) system through nondosimetric, dosimetric, and end-to-end (E2E) tests. METHODS:A comprehensive set of TPS commissioning and validation tests were developed using published guidelines. Nondosimetric validatio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14740
更新日期:2021-01-28 00:00:00
abstract:PURPOSE:Radiosurgery uses small fields and high-radiation doses to treat intra- and extracranial lesions in a single session. The lack of a lateral electronic equilibrium and the presence of high-dose gradients in these fields are challenges for adequate measurements. The availability of radiation detectors with the hi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4752211
更新日期:2012-10-01 00:00:00
abstract::Cone beam transmission CT (CB-CT) improves SPECT imaging by providing high-quality attenuation maps for attenuation compensation and for correlated SPECT and CT imaging. The present work measures the detection nonuniformity for CB-CT implemented with a gamma camera, and applies nonuniformity corrections to make CB-CT ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596838
更新日期:1992-03-01 00:00:00
abstract::A Monte Carlo method was developed and implemented to simulate x-ray photon transport. Simulations consisted of a pencil beam of monoenergetic photons with energies from 50 to 110 keV incident on water and aluminum slabs. The dependence of scatter fraction and multiple scattering on x-ray energy, scatterer thickness, ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596268
更新日期:1988-11-01 00:00:00