THE IAEA/WHO TLD POSTAL DOSE AUDIT SERVICE Zakithi Msimang SAAPMB/SARPA 2011
Introduction The idea of organizing a dosimetry audit for radiotherapy centres by the IAEA, was suggested for the first time in late 1950s. The IAEA Dosimetry Laboratory was set up early 1960s and the IAEA Dosimetry Section started its work in 1967. First trial postal dose inter-hospital comparisons, called intercomparisons at that time, were conducted by the IAEA in 1965 1966 involving Fricke dosimeters and TLDs. WHO joined the IAEA project in 1968 and since then it has actively co-operated for the service implementation worldwide. By 2010, the IAEA/WHO TLD audit service has verified the calibration of approximately 8000 radiotherapy beams in about 1700 hospitals world-wide.
The IAEA TLD TEAM From left to right: (Secretary)Sabine and Rosemary, P. Bera (TLD Technician), J. Izewska (TLD Officer and Unit Head, Dosimetry Laboratory), G. Azangwe (Dosimetrist).
Why audits? Without proper accuracy in beam dosimetry and treatment planning the required outcome of the patient s treatment cannot be achieved. Although vital for the radiotherapy process, accurate beam dosimetry and treatment planning alone cannot guarantee the successful treatment of a patient. Consequently, a comprehensive audit methodology was developed by the IAEA within the framework of the Quality Assurance Team for Radiation Oncology (QUATRO). As of 2005, QUATRO audit missions have been incorporated in the scope of IAEA activities.
QUATRO AUDIT: On request The principal aim of QUATRO is to review the radiotherapy process, including the organization, infrastructure, clinical and medical physics aspects of the radiotherapy services. It also includes reviewing the hospital s professional competence, with a view to quality improvement. QUATRO, in addition, offers assistance in the resolution of suspected or actual dose misadministration (over and under -exposures) in radiotherapy. It includes the follow-up of inconsistent results detected with the IAEA/WHO TLD postal service and helps Member States at a very early stage in the problem-solving process, focusing on prevention of incidents or accidents in radiotherapy.
TLD postal dose audit service In 2011 the NMISA was requested to co-ordinate the activities within SA. When contacted by the IAEA, distribute the IAEA/WHO TLD application forms to radiotherapy centres in the country; these application forms are invitations for centres to participate in the TLD audit (2-3 high energy photon beams per centre; regular participation every second year). Verify the current contact details of the individual medical physicists at the hospitals.
Receive the package with TLDs from the IAEA and distribute the TLDs to individual hospitals for irradiation and e-mail the electronic TLD data sheets (provided by the IAEA) to the participating hospitals. Collect TLDs from hospitals after they have been irradiated and transfer them to the IAEA for evaluation. Review the hospitals filled out TLD data sheets for integrity before transferring them to the IAEA; get any missing data from the hospitals; clarify any ambiguous or visibly incorrect entries. Receive copies of the TLD results that are emailed to the hospitals and assist in the follow-up of poor results.
Be aware of new installations of radiotherapy facilities in the country and request TLDs for them before patient treatment starts. Respond to current inquiries and issues raised by hospitals regarding the TLD audit or basic dosimetry. Maintain the registry of TLD audits in the country. Help the hospitals, if help is required, to update their data in the IAEA s DIRAC (Directory of Radiotherapy Centres) Database. Communicate global TLD results to hospitals at national meetings (in an anonymous way).
Batch 225 results The uncertainty in the TLD measurement of the dose is 1.8% (1 standard deviation); this does not include the uncertainty intrinsic to the dosimetry protocol.
Do we need a national audit programme? There has been talks that we need to have our own national audit programme to alleviate pressure on the IAEA. The to SAMPS is do we? Let us know. If you want to participate in the next IAEA TLD audit run let us know. If you are installing a new linac let us know preferable before you start treatment.
THANK YOU zmsimang@nmisa.org sjozela@nmisa.org 0128413303 0128413302 www.nmisa.org