Users Manual Part 6

IBA | B-6 | Clinical User’s Guide
Volume 1 - Treatment Session
Using the Dosimetry Manager
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Determining the Minimum Allowed MU
The Treatment Planning System (TPS) provides a dose setpoint in Monitor Units (MU)
to the Proton Therapy System (PTS), that the PTS converts into charge to be collected
in the ion chamber.
This conversion depends on the temperature, pressure, and the dose correction
factor. If the entered temperature or pressure is out of the acceptable range, the TPS
may generate treatment plans that will be rejected by the PTS.
To enable the TPS to provide treatment plans that are acceptable to the PTS, the
Minimum allowed MU for the PTS needs to be established based on the
acceptable range for temperature and pressure values.
To achieve this:
1. Enter extreme values for temperature and pressure in the Dosimetry Manager.
Suggested extreme values are:
 Temperature: 26°C
 Pressure: 90 kPa
2. The computed Meterset parameters (i.e. the Minimum allowed MUs) will be
updated accordingly in the Dosimetry Manager Settings tab (Figure B-6).
3. Enter these values in the TPS.
Figure B-6. Dosimetry Manager: Determining the Minimum Allowed MU