The Phase I clinical trials for boron neutron capture therapy (BNCT) started in May 1999 in Otaniemi, Espoo. For BNCT no uniform international guidance for the quality assurance of dosimetry exists, so far. Because of the complex dose distribution with several different dose components, the international recommendations on conventional radiotherapy dosimetry are not applicable in every part. Therefore, special guidance specifically for BNCT is needed. To obtain such guidelines (Code of Practice) a European collaboration project has been defined. The quality assurance of the dosimetry in BNCT in Finland covers each step of the BNCT treatment, which include dose planning imaging, dose planning, boron infusion, boron kinetics, patient positioning, monitoring of the treatment beam, characterising the radiation spectrum, calibration of the beam model and the dosimetric measurements both in patients (in vivo measurements) and in various phantoms. The dose planning images are obtained using a MR scanner with MRI sensitive markers and the dose distribution is computed with a dose planning software BNCT_Rtpe. The program and the treatment beam (DORT) model used have been verified with measurements and validated with MCNP calculations in phantom. Dosimetric intercomparison has been done with the Brookhaven BNCT beam (BMRR). Before every patient irradiation the relationship between the beam monitor pulse rate and neutron fluence rate in the beam is checked by activation measurements. Kinetic models used to estimate the time-behavior of the blood boron concentration have been verified using independent patient sample data. For the measurement of the absorbed doses in patients and phantoms, TL dosimeters and activation foils are used. At the moment the quality assurance of dosimetry in BNCT in Finland is according to the EU rules and planned recommendations and thus sufficient. Nevertheless microdosimetric measurement methods and Fricke gels are planned to bring to use in addition to the dosimetric methods already utilised in order to intensify the quality assurance.
|Series||University of Jyväskylä: Department of Physics. Research Report|
|Conference||Physics Days - Fysiikan Päivät 2001|
|Period||22/03/01 → 24/03/01|