16 July 2018
To ensure high quality patient treatment from the first day onward, a lot of energy has been invested into tuning the proton therapy equipment and into documenting this commissioning process. Each day, prior to the start of patient treatments, an extensive quality assurance procedure (‘Morning QA’) is performed to ensure that use and maintenance of the proton therapy equipment have not resulted in changes in this tuning.
The Morning QA protocol has been designed to validate that important machine parameters are still within their tolerance levels. Examples of such parameters are the output, the energy of the protons, the spot size of the proton beam, the spot position, etc. The QA procedure furthermore includes tests of the safety system and of the accuracy of the imaging system used for aligning the patient to the treatment beams.
Our physicists strive for this entire procedure to be very efficient and to last no more than 20 minutes per treatment room. This includes both the measurement and analysis of all important parameters. Any reduction in QA time means that more time is available for patient treatments. Such reductions have been achieved – without compromising the quality of the procedure – by using a combination of ‘smart’ hardware and software.
Most of these tools have been purchased from IBA, the supplier of the proton therapy equipment used at the UMCG proton therapy center. These include the Lynx (a fluorescent screen in combination with a CCD-camera) and Sphynx (a QA phantom with a built-in PPC05 ionization chamber). The ‘myQA’ software platform allows the streamlining and integration of all steps in the QA process and the logging of the measured data. It also allows all sub-tasks to be performed in a uniform manner, by any member of the physics group.
Irradiation of the Sphynx and Lynx with a single unique proton therapy treatment field provides information as to the accuracy of all parameters mentioned earlier. The myQA platform performs a fully automatic analysis of the measured data and documents the results. Patient treatments commence If, and only if, all parameters are within tolerance levels, thus ensuring the highest quality treatment.
Close-up of the hardware used for Morning QA