8. MEDICAL PHYSICS


The research activity of the Laboratory of Medical Physics has mainly focused on boron neutron capture therapy (BNCT), patient dosimetry, medical imaging applications, and modeling of physiological and biological systems. Research has been done in co-operation with the Helsinki University Central Hospital (HUCH), the Technical Research Center of Finland (VTT) and Finnish Centre for Radiation and Nuclear Safety (STUK).

The performance of the epithermal neutron beam of the Finnish research reactor FiR 1 has been verified in an extensive dosimetric campaign. The Finnish beam has been found to have the best therapeutic characteristics among the existing BNCT facilities. The healthy tissue tolerance study was completed at the end of March 1998. The Finnish BNCT facility is now ready for patient trials; the treatments of glioma patients is planned to start in the spring, 1999.

Calculation methods have been developed to obtain more accurate dose distributions in the patient. A computer program for calculating patient specific organ doses in diagnostic radiology has been further developed. Methods for cellular level dosimetry have also been investigated.
New MRI techniques (magnetization transfer and spin lock) have been studied. The study has been performed in vitro and in vivo in normal and in brain tumor patients. The results show that the techniques offer potentially new methods to improve tissue characterization and contrast in MR imaging. In addition, post processing techniques of diffusion and perfusion weighted MRI has been developed.

In order to optimize the BNC-treatment the kinetics of boron after BPA-fructose complex infusion has been modeled. Also, the kinetics of 111In-labelled bleomycin has been studied.

Preliminary tests were carried out with transcranial magnetic stimulation. For example, disturbing neural signal processing of the visual cortex was investigated by stimulating the occipital lobe of a subject.

Sauli Savolainen