Reconstruction of 4-MV bremsstrahlung spectra from measured transmission data

Journal Article · Tue Nov 01 04:00:00 EST 1983 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.595356· OSTI ID:5385964

Huang, P; Kase, K R; Bjaerngard, B E

Transmission data for 4-MV bremsstrahlung beams have been measured with a combination of lead and aluminum attenuators. From these data, the original energy spectra have been reconstructed using an iterative least-squares technique, previously evaluated by simulation studies. The spectra on the central axis for three similar 4-MV linear accelerators indicated no significant differences. When studying the spectra at 5/sup 0/ and 9/sup 0/ off the central axis, that at 9/sup 0/ showed the expected increase of low-energy photons. All these spectra showed a maximum photon energy of 4.5 +- 0.2 MeV. When the magnetron power was reduced, the spectrum on the central axis shifted to lower energies and the maximum photon energy decreased to 3.5 +- 0.2 MeV. The result of this experimental study confirms the conclusions from the previous simulation, that the numerical technique for analysis of transmission data can accurately represent 4-MV bremsstrahlung spectra and detect differences in energy distribution with changes in machine tuning and position in the radiation field for a 4-MV bremsstrahlung beam.

• Research Organization: Joint Center for Radiation Therapy and Department of Radiation Therapy, Harvard Medical School, Boston, Massachusetts 02115
• OSTI ID: 5385964
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 10:6; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

654001* -- Radiation & Shielding Physics-- Radiation Physics
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM
ATTENUATION
BIOMEDICAL RADIOGRAPHY
BREMSSTRAHLUNG
DIAGNOSTIC TECHNIQUES
DOSIMETRY
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY DEPENDENCE
IONIZATION CHAMBERS
IONIZING RADIATIONS
LEAD
LEAST SQUARE FIT
MAXIMUM-LIKELIHOOD FIT
MEASURING INSTRUMENTS
MEDICINE
METALS
NEUTRAL-PARTICLE TRANSPORT
NUCLEAR MEDICINE
NUMERICAL SOLUTION
PHOTON TRANSPORT
RADIATION DETECTORS
RADIATION TRANSPORT
RADIATIONS
RADIOLOGY
SPECTRA
TRANSMISSION
X RADIATION
X-RAY DOSIMETRY