MINIATURE TISSUE EQUIVALENT IONIZATION CHAMBERS AND THEIR USE

Journal Article · Fri Mar 01 04:00:00 EST 1963 · Aerospace Med.

OSTI ID:4689983

Chambers, Jr, F W

The design and application of miniature ionization chambers, particularly for evaluating the interaction of tissues with space radiations, are discussed. The design criteria for the chambers encompasses both small size and tissue equivalence, with a dose range of a few rads to several hundred rads. One design of a chamber 1.5 cm in diameter and 2 cm long is illustrated. The wall, inner electrode, and base are composed of elements representative of the tissue of interest. It is possible to compound plastics to simulate bone, fat, and muscle. Since the ionization chamber is essentially a capacitor, some parts are made of a high-grade insulating material such as Kel-F or polystyrene. When the chamber is assembled, there is a void in the cap that is filled with a gas that is similar, in elemental composition, to the wall of the chamber. The chambers are sealed to retain the gas. A system was developed in which 3 chambers are sealed in a tube. The chambers are prepared for use in a hood containing the tissue-equivalent gas atmosphere. After they are irradiated, the amount of exposure is determined by the use of an electrometer. The difference in response of the chambers when they are filled with a gas other than air, and exposed to photons of different energies, is illustrated. Three different mixtures of argon and methane were used so that the atomic number (Z) would approximate that of bone, muscle, and fat. To determine the tissue dose distribution in biological objects or suitable phantoms under given exposure conditions, the chambers were placed at various points in either the biological object or a suitable phantom containing a tissue-equivalent fluid. Three different size phantoms designed to be representative of the range of human torsos are shown and dose distribution in a Co/sup 60/ field was determined. (TCO)

• Research Organization: Naval Medical Research Inst., Bethesda, Md.
• NSA Number: NSA-17-027076
• OSTI ID: 4689983
• Journal Information: Aerospace Med., Journal Name: Aerospace Med. Vol. Vol: 34
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
ARGON
BIOLOGY AND MEDICINE
BONES
COBALT 60
DISTRIBUTION
ELECTRODES
ELECTROMETERS
ENERGY
ESTERS
FATS
GAMMA RADIATION
GASES
IONIZATION CHAMBERS
METHANE
MOCKUP
MUSCLES
PHANTOMS
PHOTONS
PLANNING
POLYMERS
POLYSTYRENE
RADIATION DOSES
RADIATION EFFECTS
TISSUES