Testing the methodology for dosimetry audit of heterogeneity corrections and small MLC-shaped fields: Results of IAEA multi-center studies

Abstract

The International Atomic Energy Agency (IAEA) has a long tradition of supporting development of methodologies for national networks providing quality audits in radiotherapy. A series of co-ordinated research projects (CRPs) has been conducted by the IAEA since 1995 assisting national external audit groups developing national audit programs. The CRP ‘Development of Quality Audits for Radiotherapy Dosimetry for Complex Treatment Techniques’ was conducted in 2009–2012 as an extension of previously developed audit programs. Material and methods. The CRP work described in this paper focused on developing and testing two steps of dosimetry audit: verification of heterogeneity corrections, and treatment planning system (TPS) modeling of small MLC fields, which are important for the initial stages of complex radiation treatments, such as IMRT. The project involved development of a new solid slab phantom with heterogeneities containing special measurement inserts for thermoluminescent dosimeters (TLD) and radiochromic films. The phantom and the audit methodology has been developed at the IAEA and tested in multi-center studies involving the CRP participants. Results. The results of multi-center testing of methodology for two steps of dosimetry audit show that the design of audit procedures is adequate and the methodology is feasible for meeting the audit objectives. A total of 97% TLD results in heterogeneity situations obtained in the study were within 3% and all results within 5% agreement with the TPS predicted doses. In contrast, only 64% small beam profiles were within 3 mm agreement between the TPS calculated and film measured doses. Film dosimetry results have highlighted some limitations in TPS modeling of small beam profiles in the direction of MLC leave movements. Discussion. Through multi-center testing, any challenges or difficulties in the proposed audit methodology were identified, and the methodology improved. Using the experience of these studies, the participants could incorporate the auditing procedures in their national programs.

Audyty kliniczne IAEA - droga do bezpiecznej i skutecznej realizacji radioterapii

“…Od wielu lat liczba przypadków raka stale rośnie na całym świecie, co skłoniło wiele rządów do inwestowania w programy zwalczania nowotworów, obejmujące między innymi instalację urządzeń do radioterapii [2]. Zakup i instalacja nowych urządzeń do radioterapii jest długim procesem i wymaga ogromnego wsparcia rządowego.…”

“…Stereotactic Radiation Therapy, SRT) czy radioterapia z modulowaną intensywnością dawki (ang. Intensity Modulated Radiation Therapy, IMRT) [2]. Jednym z przykładów działań IAEA może być podpisanie w dniu 9 czerwca 2016 r. Krajowych Ram Programowych dla współpracy technicznej Polski z IAEA na lata 2016-2021.…”

“…W ciągu ostatnich dziesięcioleci IAEA ustanowiła ramy dla prowadzenia krajowych sieci audytowych w zakresie dozymetrii w radioterapii w krajach LMI oraz opracowała metodologię i procedury kontroli dozymetrycznej wiązek terapeutycznych za pomocą szeregu skoordynowanych projektów badawczych (ang. Coordinated Research Projects, CRP) [2]. Projekty są ważnym mechanizmem IAEA służącym do organizacji międzynarodowych prac badawczych zgodnych z programem agencji [5].…”

Testing the methodology for a dosimetric end-to-end audit of IMRT/VMAT: results of IAEA multicentre and national studies

“…Since 1995, the International Atomic Energy Agency (IAEA) has conducted a series of co-ordinated research projects (CRPs) with the purpose of supporting its Member States to establish national audit activities through the development of audit methodologies and guidelines on how to structure and operate national dosimetry audit networks (DANs) [1][2][3][4]. In addition the IAEA, DAN database [5] was established to monitor audit activities; moreover, it provides information on the coverage and operations of DANs in radiotherapy.…”

“…The purpose of this work is to present both the methodology of a new remote end-to-end audit for IMRT/VMAT head treatment delivery and the results obtained in a comprehensive testing phase. This audit aims to provide an independent verification of the radiotherapy chain including imaging, dose calculation, set-up and dose delivery, representing a continuation of previously developed audit methodologies [3,4,24,25]. This remote end-to-end audit methodology was developed under an IAEA CRP and included a multicentre pilot study and national trial runs conducted by various DANs in close cooperation with the IAEA.…”