... / Radiotherapy / Medical Physics

Medical Physics

Mischa HoogemanMischa Hoogeman, Head of Medical Physics

"For radiotherapy it is very important to precisely determine the location of the tumor using a CT-scan and an MRI-scan if needed. The treatment volume, which will be deduced from the images, is always larger than the tumor itself. This is necessary because tumor cells might  be present in what appears to be healthy tissue and because the position of the tumor might change. The majority of our research focuses on mapping the mobility of tumors as accurately as possible and correcting for it with the aim of reducing the treatment volume. In one of our current research projects we study cervical tumors. The position of these tumors changes every day, since they are influenced by both the bladder and the rectum. Prior to the treatment course a patient specific library is created  containing a series of treatment plans adjusted to the possible positions of the tumor. Just before the actual irradiation a CT scan is made and the treatment plan that fits this scan the best is taken out of the library, the so-called "Plan of the Day".
In 2015 we started the construction of the Holland Particle Therapy Center in Delft, in which we expect to treat the first patients with protons in the middle of 2017.
Until now, proton therapy is not possible in The Netherlands, but it does have a significant advantage compared to radiotherapy with X-rays, as a proton beam only penetrates to a specific depth. This allows us to precisely focus the irradiation to the position of the tumor and spare the surrounding tissue. For proton therapy, image-guidance is even more important. If the protons stop a few millimeters sooner or later, part of the tumor will not be irradiated at all or an area of healthy tissue will receive the high dose that was meant for the tumor."