Use of statistical interference for tolerance determination in dose measurements

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F86652052%3A_____%2F18%3AN0000003" target="_blank" >RIV/86652052:_____/18:N0000003 - isvavai.cz</a>

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S1120179718310524" target="_blank" >https://www.sciencedirect.com/science/article/pii/S1120179718310524</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Use of statistical interference for tolerance determination in dose measurements

Original language description

The most important dosimetry quantity that is determined at radiotherapy centres is absorbed dose to water. Fixed tolerances for absorbed doses under reference conditions measured with ionisation chamber for photon resp. electron beams are usually 2% resp. 3%. The aim was to develop a new approach to the evaluation of agreement between measured and reported values based on statistical interference rather than to use fixed tolerance levels.The approach takes partial uncertainties of compared doses into consideration. Three statistical models were proposed describing three different situations to assess the critical values for rejecting the zero hypothesis on agreement:1) Two measurements performed in time with the same dosimetry chain, 2) Two measurements performed with two different dosimetry chains which were calibrated at the same calibration laboratory, 3) Two measurements performed with two different dosimetry chains at two different calibration laboratories (dose calculations are completely independent). For electron dosimetry, the uncertainty of PDD was comprehensively evaluated and its influence on recalculated dose values from reference depth to the depth of maximum dose was taken into account. In the contribution, uncertainties from TRS 398 were taken as an example. Critical values for photon and electron beams case 1 resp. 2 were 2.5% resp. 3.1% (k = 2). When uncertainty of 0.5% (k = 1) for electron PDD at zref was taken into account, critical values for electron beams case 1 resp. 2 were 2.9% resp. 3.4% (k = 2). The sensitivity of critical values to actual partial uncertainties will be shown. The models can be adopted to implement statistical interference into the decision on agreement for all quantities, where partial uncertainties are known. Published at Physica Medica, Volume 52, Supplement 1, August 2018: Abstracts from the 2nd European Congress of Medical Physics, 23-25 August 2018, Copenhagen, Denmark.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20601 - Medical engineering

Project

<a href="/en/project/FV20411" target="_blank" >FV20411: Radiotherapy Treatment Planning System - the most advanced optimization algorithms for 3D dose calculation of external beams in the body and their integration into the new generation of the treatment planning system.</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů