Abstract:
:The assessment of the radiation dose to internal organs or to an embryo or fetus is required on occasion for risk assessment or for comparing imaging studies. Limited resources hinder the ability to accurately assess the radiation dose received to locations outside the tissue volume actually scanned during computed tomography (CT). The purpose of this study was to assess peripheral doses and provide tabular data for dose evaluation. Validated Monte Carlo simulation techniques were used to compute the dose distribution along the length of water-equivalent cylindrical phantoms, 16 and 32 cm in diameter. For further validation, comparisons between physically measured and Monte Carlo-derived air kerma profiles were performed and showed excellent (1% to 2%) agreement. Polyenergetic x-ray spectra at 80, 100, 120, and 140 kVp with beam shaping filters were studied. Using 10(8) simulated photons input to the cylinders perpendicular to their long axis, line spread functions (LSF) of the dose distribution were determined at three depths in the cylinders (center, mid-depth, and surface). The LSF data were then used with appropriate mathematics to compute dose distributions along the long axis of the cylinder. The dose distributions resulting from helical (pitch = 1.0) scans and axial scans were approximately equivalent. Beyond about 3 cm from the edge of the CT scanned tissue volume, the fall-off of radiation dose was exponential. A series of tables normalized at 100 milliampere seconds (mAs) were produced which allow the straight-forward assessment of dose within and peripheral to the CT scanned volume. The tables should be useful for medical physicists and radiologists in the estimation of dose to sites beyond the edge of the CT scanned volume.
journal_name
Med Physjournal_title
Medical physicsauthors
Boone JM,Cooper VN 3rd,Nemzek WR,McGahan JP,Seibert JAdoi
10.1118/1.1312809subject
Has Abstractpub_date
2000-10-01 00:00:00pages
2393-407issue
10eissn
0094-2405issn
2473-4209journal_volume
27pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:The local depth dose gradient and the displacement correction factor for Farmer-type ionization chambers are quantified for reference dosimetry at shallow depth in single-layer scanned proton fields. METHOD:Integrated radial profiles as a function of depth (IRPDs) measured at three proton therapy centers were ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14554
更新日期:2020-12-01 00:00:00
abstract::The focal spot of a linear accelerator is often considered to have a fully stable position. In practice, however, the beam control loop of a linear accelerator needs to stabilize after the beam is turned on. As a result, some motion of the focal spot might occur during the start-up phase of irradiation. When acquiring...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1576229
更新日期:2003-06-01 00:00:00
abstract::This is an introductory tutorial to the field of microdosimetry. Following a brief historical outline, we review the physics of experimental and theoretical microdosimetry and the application of microdosimetry to radiation biology within the so-called "site" approximation. Modern interpretations of microdosimetry that...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.596616
更新日期:1991-11-01 00:00:00
abstract:PURPOSE:To review the issues a physicist may encounter in a community hospital during the transition from film/paper charts to a paperless environment with ARIA and a TrueBeam LINAC. With a lean budget, it was necessary for the physics group to take on the project management responsibilities in order save costs. This w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735291
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4792462
更新日期:2013-03-01 00:00:00
abstract::The use of electronic portal imaging devices (EPIDs) is a promising method for the dosimetric verification of external beam, megavoltage radiation therapy-both pretreatment and in vivo. In this study, a previously developed EPID back-projection algorithm was modified for IMRT techniques and applied to an amorphous sil...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2147744
更新日期:2006-02-01 00:00:00
abstract:PURPOSE:Helical tomotherapy is a complex delivery technique, integrating CT image guidance and intensity modulated radiotherapy in a single system. The integration of the CT detector ring on the gantry not only allows patient position verification but is also often used to perform various QA procedures. This convenienc...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3566067
更新日期:2011-04-01 00:00:00
abstract:PURPOSE:Current treatment planning for 90 Y radioembolization estimates lung mean dose (LMD) by measuring the lung shunt fraction (LSF) from 99m Tc-macroaggregated albumin (MAA) planar imaging and assuming a 1-kg lung mass. This methodology, however, overestimates LSF and LMD and could therefore unnecessarily limit the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13575
更新日期:2019-09-01 00:00:00
abstract::We have performed a comprehensive dosimetric characterization of the Oncura model 6711 125I seed using both experimental [LiF thermoluminscent dosimetry (TLD)] and theoretical (Monte Carlo photon transport) methods. In addition to determining the dosimetric parameters of the 6711, this report quantified: (1) the angul...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2388158
更新日期:2006-12-01 00:00:00
abstract::Direct comparisons of the National Institute of Standards and Technology's (NIST) Ritz 20 kV to 100 kV standard free-air ionization chamber and a portable variable-length free-air ionization chamber designed by the University of Wisconsin-Madison Accredited Dosimetry Calibration Laboratory (UW-ADCL) were made on NISTs...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598148
更新日期:1997-08-01 00:00:00
abstract:PURPOSE:The National Council for Radiation Protection and Measurement (NCRP) published estimates for the collective population dose and the mean effective dose to the population of the United States from medical imaging procedures for 1980/1982 and for 2006. The earlier report ignored the effective dose from radiothera...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4906190
更新日期:2015-02-01 00:00:00
abstract::Underlying characteristics in brachytherapy dosimetry parameters for medical radionuclides 137Cs, 125I, 192Ir, 103Pd, and 169Yb were examined using Monte Carlo methods. Sources were modeled as unencapsulated point or line sources in liquid water to negate variations due to materials and construction. Importance of pha...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2199987
更新日期:2006-06-01 00:00:00
abstract:PURPOSE:Integrating a linac with a magnetic resonance imager (MRI) will revolutionize the accuracy of external beam radiation treatments. Irradiating in the presence of a strong magnetic field, however, will modify the dose distribution. These dose modifications have been investigated previously, mainly using Monte Car...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12413
更新日期:2017-09-01 00:00:00
abstract:PURPOSE:Mammographic density of glandular breast tissue has a masking effect that can reduce lesion detection accuracy and is also a strong risk factor for breast cancer. Therefore, accurate quantitative estimation of breast density is clinically important. In this study, we investigate experimentally the feasibility o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13031
更新日期:2018-06-03 00:00:00
abstract::The gamma index is a tool that compares a dose distribution with a reference distribution by combining dose-difference and distance-to-agreement criteria. It has been widely used for ten years despite its high computational cost. This cost is due to both a search process for each reference point and the necessity to r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3070546
更新日期:2009-03-01 00:00:00
abstract:PURPOSE:The main objective of this work was to design a comprehensive dosimetry package that would keep all aspects of internal dose calculation within the framework of a single software environment and that would be applicable for a variety of dose calculation approaches. METHODS:Our MATLAB-based graphical user inter...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4810963
更新日期:2013-07-01 00:00:00
abstract::The dose distributions in the bifurcated vessels treated with intravascular brachytherapyline sources are complicated and depend on the bifurcation geometry consisting of a main and a branch vessel at different angles. To investigate the dosimetric effects at the bifurcation, calculations were performed on branching v...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1582813
更新日期:2003-07-01 00:00:00
abstract:PURPOSE:To investigate whether building a knowledge-based planning (KBP) model with prostate bed plans constructed from constrained hierarchical optimization (CHO) would result in more efficient model construction with more consistent output than a model built using plans from a traditional, trial-and-error-based optim...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13163
更新日期:2018-10-01 00:00:00
abstract::Magnetic resonance (MR) measurements of relaxation times and diffusion coefficient in tissue have been demonstrated to be sensitive to biological changes induced by radiation therapy. We are currently using mouse models of human glioblastoma multiforme (GBM) to study tumour response to ionizing radiation by MRI at 9.4...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2965985
更新日期:2008-07-01 00:00:00
abstract:PURPOSE:Urinary particles are particularly important parameters in clinical urinalysis, especially for the diagnosis of nephropathy. Therefore, it is highly important to precisely detect urinary particles in the clinical setting. However, artificial microscopy is subjective and time consuming, and various previous dete...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14118
更新日期:2020-07-01 00:00:00
abstract::Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast impl...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3006151
更新日期:2008-12-01 00:00:00
abstract:PURPOSE:Tomosynthesis is a promising modality for breast imaging. The appearance of the tomosynthesis reconstructed image is greatly affected by the choice of acquisition and reconstruction parameters. The purpose of this study was to investigate the limitations of tomosynthesis breast imaging due to scan parameters an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3357288
更新日期:2010-04-01 00:00:00
abstract:PURPOSE:Accurate, patient-specific radiation dosimetry for CT scanning is critical to optimize radiation doses and balance dose against image quality. While Monte Carlo (MC) simulation is often used to estimate doses from CT, comparison of estimates to experimentally measured values is lacking for advanced CT scanners ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13780
更新日期:2019-11-01 00:00:00
abstract:PURPOSE:The authors have previously reported the advantages of high-sensitivity single-photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I-123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4794488
更新日期:2013-04-01 00:00:00
abstract:PURPOSE:To present a system for robotic 4D ultrasound (US) imaging concurrent with radiotherapy beam delivery and estimate the proportion of liver stereotactic ablative body radiotherapy (SABR) cases in which robotic US image guidance can be deployed without interfering with clinically used VMAT beam configurations. M...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4964454
更新日期:2016-11-01 00:00:00
abstract:PURPOSE:To overcome the problem of organ motion in intensity-modulated radiation therapy (IMRT), gated IMRT is often used for the treatment of lung cancer. In this study, the authors investigated the accuracy of the delivered monitor units (MUs) from each segment during gated IMRT using a two-dimensional detector array...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3310806
更新日期:2010-03-01 00:00:00
abstract:PURPOSE:Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3519873
更新日期:2011-01-01 00:00:00
abstract::Monte Carlo calculations have been performed for the purpose of characterizing the dosimetric properties of three brachytherapy sources. The three sources are manufactured by Syncor Pharmaceuticals Inc. and consist of two 125I seeds (BT-125-1 and BT-125-2) and one 103Pd seed (BT-103-3). The BT-125-1 and BT-125-2 seed ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1469627
更新日期:2002-05-01 00:00:00
abstract:PURPOSE:Dedicated breast PET/CT is expected to have utility in local staging, surgical planning, monitoring of therapy response, and detection of residual disease for breast cancer. Quantitative metrics will be integral to several such applications. The authors present a validation of fully 3D data correction schemes f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3703593
更新日期:2012-05-01 00:00:00
abstract::The Gafchromic EBT was recently introduced in film dosimetry for external beam therapy (EBT). The high spatial resolution, weak energy dependence, and near-tissue equivalence of EBT films make them suitable for measurement of dose distributions in radiotherapy, especially intensity-modulated radiation therapy (IMRT). ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2362876
更新日期:2006-11-01 00:00:00