The AAPM TG -21 protocol takes into account the chamber dependent and radiation dependent parameters in determining the absorbed dose. Absorbed dose measurements are done for photon and electron beams using this protocol. Two cylindrical chambers of different wall materials and a flat chamber are made use of. The response of the chambers have been studied.

Many investogators have reported that there is some reduction in the absorbed dose at the exit surface of the body when megavoltage radiations are used. In situations, where larger or multiple fields are used, a part of the beam at the exit portion meets the metallic or rigid surface of the table top. This introduces additional backscattered photons and electrons which enhances the exit surface dose. This increase in the exit dose because of the exit surface touching the metallic portion of the table top has been measured using a commercially available parallel plate chamber. The ionisation Ratio (IR) between the chamber reading with and without table top is a measure of the increase of dose. IR is reported for three different 60Co teletherapy machines and a Linear Accelerator (for 6 and 18 MV) for the field sizes 5 x 5,10 x 10,15 x 15 and for various thicknesses of the phantom (8 to 23 cm).

Compensating characteristics and dosimetry verifications were performed on a computer designed compensator in a wax phantom. Our investigations show a uniformity of 3% to 5% over the entire field. Compensator designed in this system accounts for both external air gap and the internal tissue inhomogeneities and hence has the advantage over other compensating filters.

This dbase software is developed for computation of teletherapy, intracavity and strontium-90 beta therapy treatment time, machine output calibration, reference point dose rate for the given intracavitary source configuration, different radiobiological parameters and record manipulations.

In the present investigation alterations in biochemical and reno-somatic index values and histological picture induced by gamma radiation in kidney of Passer domesticus Linn. (House sparrow) have been studied. The birds were exposed to 10 Gy of gamma radiation and autopsied at post-radiation intervals of 1,2,3,7 and 14-days. Biochemically, increase in values of proteins, glycogen, acid and alkaline phosphatase activity and decrease in cholesterol value were noticed on day-1 which continued upto day-3. The value of reno-somatic index increased on day-1 after exposure which continued upto 3rd day, thereafter it declined. Histological changes appeared on day-1 which became severe after 3-days of exposure, these changes coincided with the biochemical findings.