Use of statistical interference for tolerance determination in dose measurements

Kód výsledku v 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>

Výsledek na webu

<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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Jazyk výsledku

angličtina

Název v původním jazyce

Use of statistical interference for tolerance determination in dose measurements

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

Use of statistical interference for tolerance determination in dose measurements

Popis výsledku anglicky

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.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

20601 - Medical engineering

Projekt

<a href="/cs/project/FV20411" target="_blank" >FV20411: Radioterapeutický plánovací systém - optimalizace nejmodernějších algoritmů pro 3D výpočet dávky od externích svazků v těle pacienta a jejich integrace do nové generace plánovacího systému.</a><br>

Návaznosti

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

Rok uplatnění

2018

Kód důvěrnosti údajů

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