Three-dimensional spatial and dosimetric characterization of radiotherapy beams using laser read-out of TLDs
A fully automated thermoluminescent detector (TLD) read-out apparatus has been designed and constructed for the express purpose of extracting spatially resolved dosimetric information using localized IR laser phosphor stimulation. A composite TLD plate has been designed that withstands the thermal stresses developed during laser heating. This detector and unique read-out scheme may be used to spatially and dosimetrically characterize ionizing radiation fields. The thermal response of TL materials cannot be fully characterized experimentally due to the inability of modern measuring techniques to accurately record the rapidly changing temperatures. Two-dimensional, time transient models have been derived to determine radial and axial temperature profiles in a TL layer when a 4 W CO{sub 2} focused or unfocused Gaussian laser beam is used to heat a single or multiple spots. Numerically derived temperature profiles were then used in a first-order kinetic model for the thermoluminescent emission. The experimental laser heated TLD read-out apparatus was used to image a {sup 60}Co radiotherapy beam. A 2.2 cm by 3.3 cm LiF detector was used to image the penumbra of a 5 cm by 5 cm collimated field of a Theratron-80. Qualitative and quantitative results agreed well with accepted beam depth dose profiles measured with ionization chambers in water bath phantoms.
- Research Organization:
- Arizona State Univ., Tempe, AZ (USA)
- OSTI ID:
- 6722290
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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61 RADIATION PROTECTION AND DOSIMETRY
RADIOTHERAPY
RADIATION DOSES
THERMOLUMINESCENT DOSEMETERS
DESIGN
COBALT 60
DEPTH DOSE DISTRIBUTIONS
GAUSSIAN PROCESSES
INFRARED RADIATION
IONIZATION CHAMBERS
LASER RADIATION
MATHEMATICAL MODELS
PHANTOMS
SPATIAL RESOLUTION
WATER
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
COBALT ISOTOPES
DOSEMETERS
DOSES
ELECTROMAGNETIC RADIATION
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LUMINESCENT DOSEMETERS
MEASURING INSTRUMENTS
MEDICINE
MINUTES LIVING RADIOISOTOPES
MOCKUP
NUCLEAR MEDICINE
NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
RADIATION DETECTORS
RADIATION DOSE DISTRIBUTIONS
RADIATIONS
RADIOISOTOPES
RADIOLOGY
RESOLUTION
SPATIAL DOSE DISTRIBUTIONS
STRUCTURAL MODELS
THERAPY
YEARS LIVING RADIOISOT
440102* - Radiation Instrumentation- Radiation Dosemeters
655003 - Medical Physics- Dosimetry