It was shown in our laboratory that a """"""""non-isolated-sensor"""""""" solid polystyrene calorimeter can be used, with irradiation periods of less than 20 minutes, for absolute measurement of absorbed dose in Cobalt-60 gamma and high energy electron fields. The """"""""non-isolated-sensor"""""""" polysterene calorimeter has the interesting features of: 1) simplicity of construction, 2) simplicity of operation without vacuum or feedback for temperature control, 3) capability of simultaneous measurements at several depths and off axis positions, 4) a very small thermal defect correction for polystyrene and 5) operation with the calorimeter in any orientation. We propose construction of the same type of calorimeter fabricated out of tissue equivalent A-150 plastic (particularly for fast-neutron fields) and solid water-equivalent plastic (water-equivalent for x rays, high energy protons and nearly so far electrons). Proposed comparisons of absorbed dose measurements with these calorimeters to that obtained with ion chambers and """"""""isolated-sensor"""""""" calorimeters will be used to establish them as devices for the absolute measurement of absorbed dose in the complex radiation fields in use in clinical radiotherapy and radiobiological research. Because of the absolute mature of the calorimeter measurement, we propose to determine the accuracy of various protocols by comparing ion chamber measurements to calorimetric results. In particular we will evaluate ICRU #14 and SCRAD-1966 which forms the foundation of x-ray dosimetry and ICRU #21 and SCRAD-1969 for electron dosimetry. Comparison of calorimetric results will also be made to those obtained with parallel plane chambers. These chambers were designed to be Bragg-Gray cavities with minimal perturbation effects. As such, they reduce the sources of error.
| Gerhard, D S; LaBuda, M C; Bland, S D et al. (1994) Initial report of a genome search for the affective disorder predisposition gene in the old order Amish pedigrees: chromosomes 1 and 11. Am J Med Genet 54:398-404 |
| Zeitz, L; Ulin, K; Caley, R (1986) Improved ""nonisolated-sensor"" solid polystyrene calorimeter. Med Phys 13:399-402 |
