The measurement of absorbed dose and dose-equivalent levels for in vivo neutron activation analysis.
A dual-chamber dosimetric method together with microdosimetric measurements have been employed to characterise the mixed neutron-gamma radiation field of a d-T neutron activation facility. Central axis and patient axis air kerma levels are reported together with patient midline dose levels determined from phantom measurements. The gamma-ray fraction of the total absorbed dose determined by the dual-chamber and microdosimetric method were found to be in agreement, within the estimated uncertainty limits. The free-air measurements indicate a uniform kerma profile across the patient couch with a midpoint kerma rate of about 0.2 mGy min-1 and a gamma-ray fraction of 14%. Phantom measurements yielded a patient midline total absorbed dose rate of about half this value and a gamma-ray fraction of 27%. A mean neutron quality factor of 9.3 derived from microdosimetric measurements was assigned to the neutron absorbed dose.
D000201:Activation Analysis / Q000379:methods*; D005720:Gamma Rays; D006801:Humans; D009501:Neutron Activation Analysis / Q000295:instrumentation / Q000379:methods*; D009502:Neutrons; D011829:Radiation Dosage; D011879:Radiotherapy Dosage