Abstract:
:In the present investigation, the necessary tests for implementing a quality assurance program for a commercial treatment planning system (TPS), recently installed at Sao Paulo University School of Medicine Clinicas Hospital-Brazil, was established and performed in accordance with the new IAEA publication TRS 430, and with AAPM Task Group 53. The tests recommended by those documents are classified mainly into acceptance, commissioning (dosimetric and nondosimetric), periodic quality assurance, and patient specific quality assurance tests. The recommendations of both IAEA and AAPM documents are being implemented at the hospital for photon beams produced by two linear accelerators. A Farmer ionization chamber was used in a 30 x 30 x 30 cm3 phantom with a dose rate of 320 monitor unit (MU)/min and 50 MU in the case of the dosimetric tests. The acceptance tests verified hardware, network systems integration, data transfer, and software parameters. The results obtained are in good agreement with the specifications of the manufacturer. For the commissioning dosimetric tests, the absolute dose was measured for simple geometries, such as square and rectangular fields, up to more complex geometries such as off-axis hard wedges and for behavior in the build up region. Results were analysed by the use of confidence limit as proposed by Venselaar et al. [Radio Ther. Oncol. 60, 191-201 (2001)]. Criteria of acceptability had been applied also for the comparison between the values of MU calculated manually and MU generated by TPS. The results of the dosimetric tests show that work can be reduced by choosing to perform only those that are more crucial, such as oblique incidence, shaped fields, hard wedges, and buildup region behavior. Staff experience with the implementation of the quality assurance program for a commercial TPS is extremely useful as part of a training program.
journal_name
Med Physjournal_title
Medical physicsauthors
Camargo PR,Rodrigues LN,Furnari L,Rubo RAdoi
10.1118/1.2742779subject
Has Abstractpub_date
2007-07-01 00:00:00pages
2827-36issue
7eissn
0094-2405issn
2473-4209journal_volume
34pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全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:PURPOSE:Cardiac motion is typically not accounted for during pretreatment imaging for central lung and mediastinal tumors. However, cardiac induced tumor motion averages 5.8 mm for esophageal tumors and 3-5 mm for some lung tumors, which can result in positioning errors. Our aim is to reduce both cardiac- and respirato...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13670
更新日期:2019-09-01 00:00:00
abstract::Estimated photon energy spectra are derived from transmission measurements using aluminium, copper, and sodium iodide absorbers. Two spectral models are proposed. One is based on a previously published model that analyzes the electron's penetration into the anode, and the production and attenuation of bremsstrahlung p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598159
更新日期:1997-05-01 00:00:00
abstract:PURPOSE:Robust registration of prone and supine colonie surfaces acquired during CT colonography may lead to faster and more accurate detection of colorectal cancer and polyps. Any directional bias when registering one surface to the other could precipitate incorrect anatomical correspondence and engender reader error....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736159
更新日期:2012-06-01 00:00:00
abstract::In external beam radiotherapy, electronic portal imaging becomes more and more an indispensable tool for the verification of the patient setup. For the safe clinical introduction of high dose conformal radiotherapy like intensity modulated radiation therapy, on-line patient setup verification is a prerequisite to ensu...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1668391
更新日期:2004-04-01 00:00:00
abstract::The synchronization of dynamic multileaf collimator (DMLC) response with respiratory motion is critical to ensure the accuracy of DMLC-based four dimensional (4D) radiation delivery. In practice, however, a finite time delay (response time) between the acquisition of tumor position and multileaf collimator response ne...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1915017
更新日期:2005-06-01 00:00:00
abstract:PURPOSE:The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4903299
更新日期:2015-02-01 00:00:00
abstract::Absorbed doses from main charged-particle beams and charged-particle fragments have been measured with high accuracy for particle therapy, but there are few reports for doses from neutron components produced as fragments. This study describes the measurements on neutron doses produced by carbon beams; microdosimetric ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2767933
更新日期:2007-09-01 00:00:00
abstract:PURPOSE:To correlate the Cole relaxation frequencies obtained from measurements of the electrical properties of breast tissue to the presence or absence of cancer. METHODS:Four-lead impedance measurements were obtained on ex vivo specimens extracted during surgery from 187 volunteer patients. Data were acquired with a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4725172
更新日期:2012-07-01 00:00:00
abstract:PURPOSE:Fluence field modulated computed tomography (FFMCT) presents a novel approach for acquiring CT images, whereby a patient model guides dynamically changing fluence patterns in an attempt to achieve task-based, user-prescribed, regional variations in image quality, while also controlling dose to the patient. This...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4829513
更新日期:2013-12-01 00:00:00
abstract:PURPOSE:The authors combine the registration of 2D beam's eye view (BEV) images and 3D planning computed tomography (CT) images, with relative, markerless tumor tracking to provide automatic absolute tracking of physician defined volumes such as the gross tumor volume (GTV). METHODS:During treatment of lung SBRT cases...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4900603
更新日期:2014-12-01 00:00:00
abstract::While simple, intravascular brachytherapy (IVB) presents a considerable potential for harm to the patient. The medical physicist maintains the responsibility to minimize the likelihood of operational problems or dosimetric errors. The principals for safe operation remain the same as with any radiotherapy treatment: to...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1524167
更新日期:2002-12-01 00:00:00
abstract::Wireless capsule endoscopy (WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal (GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which ...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1002/mp.12299
更新日期:2017-08-01 00:00:00
abstract:PURPOSE:In intensity-modulated proton therapy (IMPT), protons are used to deliver highly conformal dose distributions, targeting tumors, and sparing organs-at-risk. However, due to uncertainties in both patient setup and relative stopping power (RSP) calculation, margins are added to the treatment volume during treatme...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14347
更新日期:2020-09-01 00:00:00
abstract:PURPOSE:Breast magnetic resonance imaging is highly sensitive but not very specific for the detection of breast cancer. Opportunities exist to supplement the image acquisition with a more specific modality provided the technical challenges of meeting space limitations inside the bore, restricted breast access, and elec...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4820361
更新日期:2013-10-01 00:00:00
abstract::The anti-scatter grid has been widely used to reject scatter and increase the perceptibility of a low-contrast object in chest radiography; however, it also attenuated the primary x-rays, resulting in a substantial loss of information and an increased relative noise level in heavily attenuated regions. A more dose eff...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2739805
更新日期:2007-07-01 00:00:00
abstract:PURPOSE:Automated 3D breast ultrasound (ABUS) has gained interest in breast imaging. Especially for screening women with dense breasts, ABUS appears to be beneficial. However, since the amount of data generated is large, the risk of oversight errors is substantial. Computer aided detection (CADe) may be used as a secon...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914162
更新日期:2015-04-01 00:00:00
abstract::Methods for scatter dose calculations in brachytherapy have been developed based on the collapsed cone superposition algorithm. The methods account for effects on the scatter dose caused by the three-dimensional distribution of heterogeneities in the irradiated volume and are considerably faster than methods based on ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1290485
更新日期:2000-10-01 00:00:00
abstract::Deionized water is commonly used to couple microwave applicators to the patient surface in the administration of local hyperthermia. Profiles of the specific absorption rate (SAR) at 1-cm depth show that deionized water coupling significantly distorts the SAR distributions of the Clini-Therm 915-MHz 10 X 10 and 15 X 1...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595881
更新日期:1986-05-01 00:00:00
abstract:PURPOSE:To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. METHODS:In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced....
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4719962
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To quantify the needle tip detection errors in ultrasound images due to bevel-tip orientation in relation to the location on template grid. METHODS:Transrectal ultrasound (TRUS) system (BK Medical) with physical template grid and 18-gauge bevel-tip (20-deg beveled angle) brachytherapy needle (Bard Medical, Cov...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734916
更新日期:2012-06-01 00:00:00
abstract::The BEAMnrc/EGSnrc Monte Carlo code system is employed to develop a model of the National Research Council of Canada primary standard of absorbed dose to tissue in a beta radiation field, comprising an extrapolation chamber and 90Sr/90Y beta source. We benchmark the model against the measured response of the chamber i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1997347
更新日期:2005-10-01 00:00:00
abstract::Generating an optimized radiation treatment plan requires understanding the factors affecting tumour control. Mathematical models of tumour dynamics may help in future studies of factors predicting tumor sensitivity to radiotherapy. In this study, a time-dependent differential model, incorporating biological cancer ma...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2965923
更新日期:2008-07-01 00:00:00
abstract:PURPOSE:Intracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the ski...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3429089
更新日期:2010-06-01 00:00:00
abstract::We discuss a formalism for clinical proton beam dosimetry based on the use of ionization chamber absorbed dose-to-water calibration and beam quality correction factors. A quantity kQ, the beam quality correction factor, is defined which corrects the absorbed dose-to-water calibration factor ND,w in a reference beam of...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597768
更新日期:1996-01-01 00:00:00
abstract::Computed tomography colonography (CTC) is a minimally invasive method that allows the evaluation of the colon wall from CT sections of the abdomen/pelvis. The primary goal of CTC is to detect colonic polyps, precursors to colorectal cancer. Because imperfect cleansing and distension can cause portions of the colon wal...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1118/1.1796171
更新日期:2004-10-01 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:To evaluate a three-equation three-unknown dual-energy quantitative CT (DEQCT) technique for determining region specific variations in bone spongiosa composition for improved red marrow dose estimation in radionuclide therapy. METHODS:The DEQCT method was applied to 80/140 kVp images of patient-simulating lumb...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4870378
更新日期:2014-05-01 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
pub_type: 杂志文章
doi:10.1002/mp.14023
更新日期:2020-04-01 00:00:00
abstract::Luminance scatter fractions were measured for patients and phantoms in various regions of the chest film. Scatter fractions were found to be highly variable, being quite high in the regions of the chest with a large equivalent tissue thickness (e.g. mediastinum, chest wall, and subdiaphragmatic areas). For example, ap...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595027
更新日期:1981-09-01 00:00:00