Radiation therapy facility risk analysis in Brazil with SEVRRA software.

Risk assessment deals with processes, accident-initiating events, barriers and risk ratings to unveil the fragility and weakness of some processes; within this study, specifically related to radiation therapy facilities. Barriers are technical or organizational safety measures put in place to avoid, prevent, detect, control, reduce or mitigate the consequences of an accident once an initiating event has occurred. In this work, radiological risk analysis was performed for a set of 20 Brazilian radiotherapy facilities making use of the freeware sevrra risk-management software. The objective of this study was to define parameters that could be useful in creating an overall risk profile. This profile would be helpful for establishing priorities for decision making and support a risk-informed regulatory process. The most relevant missing barriers in facilities were identified according to three parameters: the 'importance index', 'impacted facilities index' and the 'barrier-effectiveness index'. Barriers such as 'in vivo dosimetry in the first treatment session', 'weekly in vivo dosimetry to detect errors in the dose delivering process', 'annual external audit for the control of reference dose rate' and 'independent verification of calibration by various medical physicists with a different dosimetry equipment' were found to be the most effective in reducing the risk level of the facilities. The present investigation reinforces the need to strengthen the mechanisms that guarantee the effectiveness of such barriers in radiation therapy procedures.

Ion chambers compliance results of Brazilian radiation therapy facilities.

The Brazilian Nuclear Energy Commission (cnen) has been making a constant effort to keep up to date with international standards and national needs to strengthen the status of radiological protection of the country. The guidelines related to radiation therapy facilities have been revised in the last five years in order to take into consideration the most relevant aspects of the growing technology as well as to mitigate the accidents or incidents observed in practice. Hence, clinical dosimeters have gained special importance in this matter. In the present work, we discuss the effectiveness of regulation and inspections to the enforcement of instrument calibration accuracy for the improvement of patient dosimetry and quality control. As a result, we observed that the number of calibrated instruments, mainly well chambers, is increasing each year. The same behavior is observed for instruments employed in technologically advanced radiation treatments such as intensity modulated radiotherapy, volumetric therapy and stereotatic radiosurgery. We ascribe this behavior to the new regulation.