Human diploid fibroblasts, strain MRC-5, were sequentially irradiated with 60Co gamma rays at intervals during their in vitro lifespan. The results indicate that 3 or 6 doses of 1 Gy can increase lifespan, and the same was true for cells treated with 3 doses of 3 Gy. Higher doses (5 x 3 Gy) did reduce growth potential, suggesting either that mid-late passage cells become more sensitive to radiation, or that doses beyond a given threshold reduce population lifespan by multiple cellular hits. The life extension induced by gamma rays might be due to an induced hypermethylation of DNA.
Tinospora cordifolia is widely used in Ayurvedic medicines. It is known for its immunomodulatory, antihepatotoxic, antistress and antioxidant properties. It has been used in combination with other plant products to prepare a number of Ayurvedic preparations. The present study was undertaken to evaluate the radioprotective effect of an aqueous extract of Tinospora cordifolia (TC) against (60)Co gamma radiation.
Measurements of the intensity distribution of a 60-Co beam revealed a significant field distortion caused by minor misalignment of the collimator assembly which was not detected by routine methods. Accurate monitoring of radiation intensity distribution and periodic visual inspection of collimators are suggested for early detection of this problem.
A new single-channel detector system has been developed to perform routine quality assurance of 60Co and high-energy therapy machines. This detector is composed of an orange plastic scintillator, optically coupled to a radiation-resistant polycarbonate light pipe and a shielded silicon photodiode imbedded in a hollow solid water phantom block. No temperature and pressure corrections are required. Stability results were consistent with standard deviations fluctuating from 0.03% up to 0.09% for 60Co and from 0.05% up to 0.18% for other high energies.