Comparison of dosimetry audit results in radiotherapy determined with new AAPM/IAEA CoP on small field dosimetry and with previous methods

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F86652052%3A_____%2F18%3AN0000033" target="_blank" >RIV/86652052:_____/18:N0000033 - isvavai.cz</a>

Result on the web

<a href="https://guarant.topinfo.cz/iupesm2018/en/book-of-abstracts" target="_blank" >https://guarant.topinfo.cz/iupesm2018/en/book-of-abstracts</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Comparison of dosimetry audit results in radiotherapy determined with new AAPM/IAEA CoP on small field dosimetry and with previous methods

Original language description

The National Radiation Protection Institute performs independent dosimetry audits of all units used in radiotherapy after acceptance testing in the Czech Republic. Absorbed dose to water under reference conditions is determined within audit together with relative dosimetry parameters such as output factors for different field sizes. In November 2017, new AAPM/IAEA Code of practice was published for dosimetry of small static and non-standard fields used in external beam radiotherapy, but indeed these fields were used clinically before. The non-standard fields started to be audited in 2010 in the Czech Republic when first CyberKnife has been installed in the Czech Republic. Since then, linacs with FFF beams at 5 centres and 2 TomoTherapy units at 2 centres were commissioned. The auditing group had to cope with challenges in terms of choice of reference conditions, detectors most suitable for measurement and available at that time, sufficient phantoms, published correction factors, dose uncertainty estimation, etc. Determined doses had to be compared to doses calculated by treatment planning system and/or measured by audited centre. The aim of this contribution was to compare the results that were obtained for non-standard fields in external radiotherapy in a traditional way (using the concepts described in TRS 398 and related papers available formerly) and recalculated according to the TRS 483. In total, 4 FFF linac (10 FFF beams) measured with PTW 30013 ionisation chamber, 2 Tomotherapy units measured with NE 2571, 1 CyberKnife measured with PTW 30013 and CC01, 1 Leksell Gamma Knife measured with PTW 31010. Additional measurements were performed to confirm recalculated values. The influence of new paradigm to former dose results and uncertainties was estimated including formerly used and recently recommened correction factors in small field dosimetry. Presented at World Congress on Medical Physics & Biomedical Engineering, IUPESM 2018, 3-8 June 2018, Prague, Czech Republic: Book of Abstracts.

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

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2018

Confidentiality

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