Investigation of the microdosimetric characteristics of broad, therapeutic beams of negative pions at LAMPF

Conference · Sun Jan 01 04:00:00 EST 1978

OSTI ID:6788233

Dicello, J F; Zaider, M

Preclinical human studies with negative pions are presently being conducted at the Clinton P. Anderson Meson Physics Facility (LAMPF) of the Los Alamos Scientific Laboratory. Presently, the proton current at LAMPF is 300 ..mu..A, average, and the instantaneous pion rate at the biomedical channel is about 2.4 x 10/sup 7/ pions/sec, cm/sup 2/. This corresponds to a dose rate of about 6 rad/min in a 1 liter volume. Conventional microdosimetric techniques are not applicable at these event-rates because of detector damage, gas breakdown, pileup and deadtime effects, and saturation of the electronics. A new microdosimetric system developed at LAMPF in order to overcome these problems is described. Treatment fields as large as 17 x 17 cm/sup 2/ and as deep as 10 cm have been developed. The radiation quality of such pion beams is changing rapidly throughout the treatment volume. For this reason, microdosimetric data have been obtained for a broad, therapeutic beam (10 cm deep, 1 liter volume) as part of a continuing program to characterize those aspects of the radiation quality which produce changes in the biological response. Microdosimetric data have been obtained at several positions along the central axis of the beam in the peak region. The characteristics of the broad, pion beams are discussed and are compared with those of a narrow pion beam, with neutron data, and with data for broad, heavy-ion beams. An attempt is made to calculate broad beam distributions from data for narrow beams for purposes of treatment planning, and the results are compared with the measured spectra.

• Research Organization: Los Alamos Scientific Lab., N.Mex. (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6788233
• Report Number(s): LA-UR-78-1205; CONF-780534-1
• Country of Publication: United States
• Language: English

Related Subjects

560151* -- Radiation Effects on Animals-- Man
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACCELERATORS
BEAMS
BOSONS
DATA ANALYSIS
DOSE RATES
DOSIMETRY
ELECTRONIC EQUIPMENT
ELEMENTARY PARTICLES
HADRONS
LAMPF LINAC
LINEAR ACCELERATORS
MEDICINE
MESON BEAMS
MESON FACTORIES
MESONS
MICRODOSIMETRY
NUCLEAR MEDICINE
PARTICLE BEAMS
PION BEAMS
PIONS
PIONS MINUS
PLANNING
PSEUDOSCALAR MESONS
RADIATION QUALITY
RADIOLOGY
RADIOTHERAPY
THERAPY