Change search
ReferencesLink to record
Permanent link

Direct link
On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry
Stockholm University, Faculty of Science, Department of Physics.
2012 (English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 8, 2117-2136 p.Article in journal (Refereed) Published
Abstract [en]

A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for Ir-192 and Co-60 gamma-ray spectra. The aim of this work was to establish 'an envelope of uncertainty' based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for mu(en)/rho with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, u(c), for the mu(en)/rho values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For Co-60 and Ir-192, u(c) is approximately 0.1%. The Type B uncertainty analysis for the ratios of mu(en)/rho values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (mu(en)/rho)(graphite,air) and (mu(en)/rho)(graphite,water) are 1.5%, and 0.5% for (mu(en)/rho)(water,air), decreasing gradually down to u(c) = 0.1% for the three mu(en)/rho ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res. 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (mu(en)/rho)(graphite,air) for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication).

Place, publisher, year, edition, pages
2012. Vol. 57, no 8, 2117-2136 p.
National Category
Physical Sciences
URN: urn:nbn:se:su:diva-76050DOI: 10.1088/0031-9155/57/8/2117ISI: 000302567100003OAI: diva2:525783
3Available from: 2012-05-09 Created: 2012-05-08 Last updated: 2012-05-09Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Andreo, Pedro
By organisation
Department of Physics
In the same journal
Physics in Medicine and Biology
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 29 hits
ReferencesLink to record
Permanent link

Direct link