Prostate and other soft-tissue cancers are often treated with radioactive sources implanted or inserted into the body. But monitoring the dose is problematic.
In high dose rate brachytherapy, tumours are targeted by radioactive sources temporarily inserted into the body.
“Until now, it has not been possible to check at the time of delivery whether the doses received by the tumour and by surrounding healthy tissue matched the planned levels,” says Dr Rick Franich, Medical Radiation Physics group leader at the University’s Health Innovations Research Institute.
Rick and researcher Ryan Smith believe their new system will be able to solve this problem, not only enabling closer control of the progress of therapy, but also recording information on patient dosage and outcomes that can be used to conduct much more finely tuned clinical research.
The researchers so far have determined that their approach can achieve what they want, and are now developing the necessary algorithms and safety protocols to control it. They hope their technology will be ready for use in the clinic in late 2011.
The new method relies on placing a silicon flat panel detector behind the patient which acts like a giant digital camera. The images are formed as it detects gamma rays emitted by the radioactive source coming out through the patient’s body. The trajectories of the rays can be analysed in real-time, so the movement of the source can be tracked.
The system will also use the information to calculate the radiation dose received at the panel surface, and the three-dimensional dose distribution in the patient. If a discrepancy with planned therapy is detected, treatment can be interrupted.
Photo: Computer simulation of brachytherapy prostate treatment showing radioactive source trajectories through the pelvic region
Credit: Rick Franich
Health Innovations Research Institute, RMIT University, Rick Franich, rick.franich@rmit.edu.au, www.rmit.edu.au/study-with-us/health-and-medical-sciences/medical-radiations/