Theraeputic Medical Physics: Brachytherapy plays an important role in the treatment of female gynecological cancers. A good part of the century long clinical experience has come from use of a tandem and ovoid applicator set which has tungsten shields in it to minimize the radiation dose and hence radiation toxicity to the nearby critical structures, rectum and bladder. Unfortunately due to practical limitations, the dose reduction due to their presence was ignored and hence the clinical experience gained relies on incorrect recorded dosage to these two vital organs. Thus the published tolerance values in literature for these structures can not be used for new set of CT/MR compatible applicators which can not have any shielding due to imaging artifacts. We are presently developing experimental methods to determine the difference in the recorded and actual radiation dosage to these organs using various detectors. This study will provide guidance to properly apply corrected constraints for rectum and bladder using CT/MR applicators.
Project 2 is based on collaboration with researchers in Carestream Health, Rochester, NY. We have successfully demonstrated a novel algorithm to use Electronic Portal Imaging Detector (EPID) to track the lung tumor in real time without requiring any external surrogate. It is very promising field which one day may help us to gate the treatments of lung patients using this technique which will be simple and yet free of less accurate external surrogates. This will also result in the reduction in tumor margin commonly employed for lung cases resulting in lower radiation toxicity to these patients.
In radiation therapy, it is very important to accurately reproduce the patient position during treatment as was used during treatment simulation. This is presently carried out using the technical information recorded manually during simulation. In another project, we are seeing the feasibility of using digital cameras along with information extracted from the patients treatment plan to verify that the patients is not only in its right position before the treatment is started but also to continuously track and monitor the patients’ position during his/her entire treatment. Our initial results are very promising in this study.
In yet another project, we are trying to find optimal beam arrangements and their mathematical characteristics to achieve an optimal treatment plan which best satisfies clinical constraints using a super computer at CCR, UB. We have already demonstrated the proof of concept in which patient specific images along with appropriate image segmentation‘s and desired clinical constraints are fed to a cluster of computers at CCR where hundreds of combinations are tried using a process called Genetic Algorithm to come to an optimal solution. The process has been successfully demonstrated for 3D conformal therapy and we wish to extend it for intensity modulated radiotherapy (IMRT) in near future as well.