ESTRO 36 Abstract Book

S942

ESTRO 36 2017

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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

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

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

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.

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.

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

, C. Ling

, R. Scheuermann

, D. Mihailidis

, J.

Metz

University of Pennsylvania, Radiation Oncology,

Philadelphia, USA

Varian Medical Systems, Reserach and Development,

Palo Alto- CA, USA

Purpose or Objective