For treating certain types of cancer, it can be advantageous to target tumours with beams of ions, most commonly protons. One of the big advantages is that such beams can be tuned to deposit almost all their energy in specific locations, thereby reducing damage to intervening tissue and limiting the toxicity in patients. This is particularly important in sensitive “crowded” areas of the body, such as the head, neck and pelvic regions. In this video interview, Katia Parodi of Ludwig-Maximilians University in Germany introduces the science of ion-beam therapy and describes an acoustic technique she is developing to monitor its efficacy.
Currently there are around 70 operational proton therapy centres worldwide, with a similar number under construction. The original centres required large-scale infrastructures with particle accelerators and large gantries, but smaller “single-room” options are starting to appear. In addition, medical physicists are seeking ways to track precisely the location of proton-beam deposition in real-time, which is important because anatomies change slightly during treatment sessions. Parodi describes one solution being developed by her group, which involves attaching transducers to patients to track acoustic waves generated by the thermal expansion of tissues during treatment sessions.
The principle of this ionoacoustic monitoring was first demonstrated in the 1990s, but interest is increasing due to recent advances in proton beam technologies including the so-called “pencil beams” that can scan tumours with a high degree of precision. One of the really promising aspects is that it could in principle be combined with ultrasound imaging, enabling medical professionals to image the proton beams and the patient anatomy simultaneously. Parodi speaks about the next steps required to translate this research from the lab to a clinical setting. She also believes it is becoming increasingly important for medical physicists to develop a more fundamental understanding of biological processes.
This video is the second in a three-part series profiling pioneering medical physicists. Last week’s video featured Bas Raaymakers from UC Utrecht speaking about using magnetic resonance imaging (MRI) alongside radiotherapy. Look out for the final instalment of the series next week. Each video features a medical physicist from the board of Physics in Medicine & Biology, a journal published by IOP Publishing, which also publishes Physics World.