An interview with Robin Garcia, Chief Medical Physicist at Institut Sainte Catherine in Avignon, France in March 2017.

What is your current clinical environment ?

Institut Sainte Catherine in Avignon is a dedicated cancer care institution. Each year, 2500 patient benefit from radiotherapy with an Aqilon/Toshiba CT, six Varian linacs (1 clinac MLC 80 leaves, 1 UNIQUE mono energy 6MV, 2 Clinac MLC 120 leaves, OBI, VMAT, 2 TrueBeam STX). Aria and Eclipse.

Seven Medical Physicits and 8 Dosimetrists manage the dosimetry of 3D-RT, VMAT, Intra and extra cranial Stereotactic plans, mono isocentric breast, 4D-CT and DIBH (SDX/DynR).

A part of the Medical Physicists time is dedicated to clinical and physics research.

What are your most crucial concerns with overall treatment using Stereotactic?

The first concern was about small beam dosimetry which needed to implement sophisticated validations with multiple detectors.The definition of the MLC parameters and their physical adjustment neededimportant and precise work. Then, applying the techniques and methods to the patients, we had to implement quick but efficient dosimetric verification and validation

What do you do to improve the QA for these types of treatments?

We use all complementary ways/tools (2D array, Delta4, PDIP, Film dosimetry, Gel dosimetry) to measure the delivered dose to guarantee the correct settings. We focus on dosimetric measurements to improve the MLC parameters and manage the modulation complexity to obtain the best correlation between planning and delivery.

What is the most important benefit from your QA?

Due to high daily doses and potential risks, a good QA helped us to secure all the processes and obtain the confidence of all professionals.

How do you use the Delta4 and what value does the Delta4 bring you for this application?

The Delta4 Phantom is used for Complex treatments, the same physicist tool as the ion chamber for simple beams. It is used in the first steps of any implementation to configure and validate. Then, it helps to validate irradiation that are badly measured with other systems. All the flat detectors such as portal or 2D array provide wrong analyses due to the continuous measurement face to the beam. The Delta4 gives a real 3D dose distribution without artificial errors.

Where do you see the future for treatments in 5-10 years?

The Future of radiotherapy will benefit from automation in planning and treatment. The increase of complexity has also increased the time of all steps. Radiotherapy needs to limit the amount of work to favour the possibilities to implement new techniques and methods.

The Future of Radiotherapy is also about the adaptation during the course of treatment. It will likely need ten years of developments and implementations. Many softwares and tools will appear to go with this evolution. We will also  benefit from MRI based RT.

Another future development , which will take time, and will always need developments is the transit Dosimetry, it will be one of the link with adaptive procedures.