ESTRO 36 Abstract Book

S942 ESTRO 36 2017 _______________________________________________________________________________________________

in a trajectory log text file. The TrueBeam Log Viewer application can list these parameters versus time for user- selected accelerators and data interval. All lists can be sorted with respect to any column, non- clinical events can be ignored, events not matching a user- selected main fault code or fault description string can be ignored, and all lists can be exported to Excel for further analysis.

Table 1 shows RLIC results for AC and EPID. AC data is given by phantom software. It can be noticed that the coincidence for both isocenters is lower for the EPID, this can be explained because AC just take into account one direction in each gantry angle .

Results Sorting the list of events with respect to the main fault code provides a fast overview of the number faults for each fault type and accelerator, facilitating an easy prioritization of faults (see figure 1). In addition, treatment plan details and mechanical axes for each event (for example beam energy, the number of monitor units, the patient ID, and the gantry angle) are valuable for the identification of the root cause of the corresponding fault. A more detailed insight into the root cause of a fault can be gained by analyzing node records of the corresponding event in Excel. An example of a node record for a gantry fault is shown in figure 2. Also trending of the main system parameters from the trajectory log text files with Excel is a strong troubleshooting tool.

The sensitivity of AC for RLIC is fairly good taking into account the uncertainties of measurement 1 mm between laser positions. Conclusion ArcCheck software is capable of give a fairly accurate measurement of the laser and radiation isocenters coincidence, taking into account to add about 0.5 mm displacement in X and Z directions. EP-1737 Efficient troubleshooting of accelerator faults using the TrueBeam Log Viewer software application L.H. Praestegaard 1 1 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark Purpose or Objective In case of an accelerator fault, the identification of the root cause often takes much longer time than the correction of the fault itself (for example replacement of a component or a calibration). Accordingly, the uptime of an accelerator very much depends on an efficient troubleshooting process. In addition, an overview of existing faults is essential for an efficient planning of service tasks. Material and Methods The TrueBeam Log Viewer application is an in-house software application developed in C#. For the Varian TrueBeam system all faults occurring during beam on produces an event. With the application all events, for user-selected accelerators and data interval, can be listed including fault details, treatment plan details, mechanical axes, imaging parameters, and imaging arm positions at the time of the event (see figure 1). For each event the TrueBeam system produces a number of node records, each with detailed information about system parameters versus time just before the fault occurred (for example all MLC positions and motor currents at 500 time steps of 10 ms). All node records are readily available in the application from the list of events. In addition, the application can generate an event alarm, including the corresponding event data, each time an event occurs for user-selected accelerators. For each dynamic beam delivery the TrueBeam system also produces a single log of the main system parameters

Conclusion The TrueBeam Log Viewer application is an efficient tool both for obtaining an overview of existing faults and for identification of the root cause of faults. In our clinic the application has provided a much more substantiated prioritization of service tasks and faster identification of the root cause of faults. Varian has no service tools with this capability. EP-1738 Performance of a new EPID panel and opportunities for a fast MV-CBCT acquisition. C. Kennedy 1 , C. Ling 2 , R. Scheuermann 1 , D. Mihailidis 1 , J. Metz 1 1 University of Pennsylvania, Radiation Oncology, Philadelphia, USA 2 Varian Medical Systems, Reserach and Development, Palo Alto- CA, USA

Purpose or Objective