ON THE USE OF THIMBLE CHAMBERS IN PHANTOMS
>The results are given of investigations on the validity of the assumption that the thimble chamber will record faithfully (within 5%) the exposure dose delivered at the position of the center of a chamber. The Victoreen condenscr rmeter was examined over a wide range of quality and other physical factors. A detailed discussion is given on corrections applicable to readings obtained in phantoms and on corrections applicable to readings resulting from exposures in air. The experiments involved measurements in air and at various depths in a Presdwood phantom, with Victoreen thimbles of nominal range 25, 100, 250, and 1000 r, for two field sizes, and for nine radiation qualities. It was concluded that owing to absorption of both primary and secondary radiation in the brass barrel of the thimble, the reading is reduced below that which would otheuise be observed, and by an amount ranging up to 9% for the conditions studied. The correction required was shown to depend on quality, field size, and depth in the phantom, but only slightly on thimble range. Correction graphs are included. The data presented display a pattern which is felt to be consistent and in agreement with a qualitative argument quoted. (P.C.H.)
- Research Organization:
- Univ. of California, San Francisco
- NSA Number:
- NSA-16-006660
- OSTI ID:
- 4820850
- Journal Information:
- Radiology (U.S.), Journal Name: Radiology (U.S.) Vol. Vol: 78; ISSN RADLA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
CALIBRATION OF THE ABSORBED DOSE PRODUCED IN WATER BY BETATRON ELECTRONS WITH THE BENZOIC-ACID DOSIMETER
Comparison of ion chamber and TLD dosimetry in mammography