Research of 131Cs Radionuclide Production for Brachytherapy with Photonuclear Method

Purpose: Currently a brachytherapy method with 125I received widespread acceptance in the treatment of prostate cancer. However, since 2003, 131Cs radio-implants have been approved for clinical use in the treatment of this type of cancer. To investigate alternative 131Cs receiving channels using electron accelerators and to evaluate the effectiveness of this method for its use in brachytherapy. Material and methods: To study alternative channels for the 131Cs production using electron accelerators and to evaluate the efficiency of this method, we irradiated the natural cesium target (0.35 g) on a pulsed microtron with an electron energy of 55 MeV, an average amperage of 40–45 nA during 80 min. Results: The 131Cs activity in the irradiated sample was 12.2 ± 1.0 μCi at the end of irradiation. Conclusion: In brachytherapy, 10 to 60 micro-sources are usually used to treat a patient. The activity of one therapeutic micro source is 131Cs of the order of 10–3 Ci. Thus, the development of the required amount becomes possible when using electron accelerators with currents of the order of 50 mA. In the future it is also necessary to investigate 131Cs in the electron energy range 30–45 MeV for choosing the optimal irradiation regime.

Benzophenone Suppression of Quercetin Antioxidant Activity towards Lipids under UV-B Irradiation Regime: Detection by HPLC Chromatography

Quercetin, a well-known flavonoid antioxidant, has been employed to control benzophenone-sensitized peroxidation of the lipid mixture in methanol solution, induced by continuous UV-B irradiation. Surprisingly, the detected quercetin antioxidant activity was almost negligible. The presented data suggests that the reason is not in its own UV-B-induced degradation but rather in its interrelationship with benzophenone during UV-B stress. On the other side of this relationship, benzophenone anticipated sensitizing role towards lipids; that is, the initiation of lipid peroxidation has been affected as well. These results, obtained by HPLC chromatography, partly confirm but partly relativize to some extent recent results obtained with the same system by spectrophotometric method.

Seed Germination of Annual Vinca Responds to Irradiation and Temperature

Seeds of `Dawn Carpet' and `Little Bright Eye' annual vinca [Catharanthus roseus (L.) G. Don] were subjected to 32 treatments, arranged as a four × four × two factorial. For each cultivar, seeds were exposed to one of four temperatures (15, 20, 25, or 30C) during the 8-hour (day) and 16-hour (night) portions of the cycle. Within each temperature regime, half the seeds of each cultivar were irradiated for 1 hour daily, and the other half remained in constant darkness. Final germination percentages were suppressed at 15C day or night temperatures; at temperatures ≥20C, there were no significant differences between treatments. Heat input (daily degree hours) was a controlling factor in germination; different temperature cycles with equivalent numbers of daily degree hours had similar effects on germination response. There was a strong interaction between temperature and irradiation regime for both cultivars. Irradiating seeds for 1 hour/day reduced final germination percentages under cool (15C) conditions; response was not adversely affected when seeds at 15C were germinated in darkness. In a second experiment, seeds at 25C were exposed to daily photoperiods of 0, 1, 2, 4, 8, 12, or 24 hours. Germination percentages obtained in darkness and at photoperiods ≤12 hours were equivalent. Twenty-four-hour photoperiods suppressed germination compared to all other irradiation treatments.