AN OXYGEN BAROTHERAPY APPARATUS FOR USE WITH THE 4-Mev ACCELERATOR

Journal Article · Fri Dec 01 04:00:00 EST 1961 · J. Coll. Radiol. Australasia

DOI:https://doi.org/10.1111/j.1440-1673.1961.tb03381.x· OSTI ID:4634871

van den Brenk, H A.S.

Requirements governing the de sign of high-pressure oxygen equipment for use in radiotherapy are discussed and one such barotherapy apparatus is described and illustrated. This apparatus, manufactured by the Commonwealth Aircraft Corporation for the Peter MacCallum Clinic, Melbourne, is designed to operate at pressures of 60 psi oxygen (or less) in conjunction with a 4-Mev linear accelerator. It provides the means of obtaining a uniformity in dosimetry of tumors to be treated, comparable with conventional techniques. It also provides simple and accurate planning and positioning of patients before treatment, comparable with the conventional methods now in use. Multifield treatments can be given without decompression and recompression of the patient. The occupation time in the accelerator room is cut to a min and does not impose restrictions on the use of the accelerator for other purposes. Studies were made of the influence of the transparent plastic material used for portals in the apparatus, on the tissue dose. Interposing of a sheet of Perspex (or other material) between the target and the skin was found to modify the beam. The dose rate in air at the skin surface was decreased by absorption in the Perspex. However, this decrease was largely offset by using a 100-cm target-tumor center distance instead of 100-cm target-skin distance, and a dose rate in excess of 100 rad/min could be obtained. Even large single dose fractions of the order 1000 rad were thus easily managed. However, the depth in tissue at which the max absorbed dose rate (peak dose) occurred diminished as the distance between the inner surface of the Perspex and skin decreased. When the material is in contact with the skin the percentage skin dose is 100% while for a separation of 5 cm the percentage skin dose decreases to approximates 50% for a 25-cm/sup 2/ field. Although these factors did not seriously affect treatment, they had to be taken into consideration in providing corrected dosimetry and assessing skin reactions under high oxygen pressures. Isodose patterns obtained with the 4-Mev beam in the pressure vessel are illustrated. (BBB)

• Research Organization: Cancer Inst. Board, Melbourne
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-038665
• OSTI ID: 4634871
• Journal Information: J. Coll. Radiol. Australasia, Journal Name: J. Coll. Radiol. Australasia Vol. Vol: 5
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
AIR
BEAMS
BIOLOGY AND MEDICINE
LABORATORY EQUIPMENT
LIGHT
LINEAR ACCELERATORS
MAN
METHACRYLIC ACID
OPACITY
OXYGEN
PERSPEX
PLANNING
POLYESTERS
POLYMERS
PRESSURE
PRESSURE VESSELS
RADIATION DOSES
RADIOTHERAPY
REFLECTION
SHEETS
SKIN
TUMORS
USES