Marta Ptaszkiewicz

EPR studies of free radicals decay and survival in gamma irradiated aminoglycoside antibiotics: sisomicin, tobramycin and paromomycin.

Radiation sterilization technology is more actively used now that any time because of its many advantages. Gamma radiation has high penetrating power, relatively low chemical reactivity and causes small temperature rise. But on the other hand radiosterilization can lead to radiolytic products appearing, in example free radicals. Free radicals in radiative sterilized sisomicin, tobramycin and paromomycin were studied by electron paramagnetic resonance (EPR) spectroscopy. Dose of gamma irradiation of 25kGy was used. Concentrations and properties of free radicals in irradiated antibiotics were studied. EPR spectra were recorded for samples stored in air and argon. For gamma irradiated antibiotics strong EPR lines were recorded. One- and two-exponential functions were fitted to experimental points during testing and researching of time influence of the antibiotics storage to studied parameters of EPR lines. Our study of free radicals in radiosterilized antibiotics indicates the need for characterization of medicinal substances prior to sterilization process using EPR values. We propose the concentration of free radicals and other spectroscopic parameters as useful factors to select the optimal type of sterilization for the individual drug. The important parameters are i.a. the τ time constants and K constants of exponential functions. Time constants τ give us information about the speed of free radicals concentration decrease in radiated medicinal substances. The constant K(0) shows the free radicals concentration in irradiated medicament after long time of storage.

Proton radiotherapy facility for ocular tumors at the IFJ PAN in Kraków Poland

The proton radiotherapy facility for the eye melanoma treatment is under development at the Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN) in Krakow. The facility uses protons, accelerated by the AIC-144 isochronous cyclotron up to the energy of 60 MeV. The infrastructure and all necessary equipment have been already installed. The paper describes the present status of the facility, gives results of the preliminary beam measurements and shows future perspectives.

Radiation exposure at the proton eye therapy facility at IFJ in Kraków

The proton radiotherapy facility for the treatment of eye tumors is under development at the Institute of Nuclear Physics (IFJ) in Kraków. The optical line installed at the treatment room is applied to form and monitor the 60 MeV proton beam provided by the AIC-144 isochronous cyclotron. Typical proton dose rates measured at the isocentre varied between 0.01 and 0.5 Gy/s. The intensities of the secondary radiation field inside and around the treatment room have been measured with a stationary monitoring system. Four sets of radiation monitors provide the continuous monitoring of gamma and neutron radiation during the operation of the facility. Monte Carlo calculations have been performed for understanding the structure of the radiation field inside the treatment room. Typical ambient dose equivalent rates inside the treatment room vary between 100 and 800 μSv/h for neutrons and between 10 and 130 μSv/h for gamma rays. The maximum values were found to be 2.5 mSv/h and 0.3 mSv/h respectively. The ambient dose equivalent rates outside the therapy room were not higher than 2.5 μSv/h for neutrons and 0.35 μSv/h for gamma rays. The end of the beam line, the optical line and the beam scattering system are main sources of the secondary radiation. Optimisation and shielding of these elements will reduce the patient and facility personnel exposure to the secondary radiation.

Applicability of EPR/alanine dosimetry for quality assurance in proton eye radiotherapy

A new quality assurance and quality control method for proton eye radiotherapy based on electron paramagnetic resonance (EPR)/alanine dosimetry has been developed. It is based on Spread-Out Bragg Peak entrance dose measurement with alanine detectors. The entrance dose is well correlated with the dose at the facility isocenter, where, during the therapeutic irradiation, the tumour is placed. The unique alanine detector features namely keeping the dose record in a form of stable radiation-induced free radicals trapped in the material structure, and the non-destructive read-out makes this type of detector a good candidate for additional documentation of the patients exposure over the therapy course.