Portable dose equivalent meter based on microdosimetry
It is generally accepted that the physical basis of the relative biological effectiveness of different radiations is the difference in the spatial distribution of ionization along the charged particle tracks. Thus it is possible to measure physical quantities which may be related to biological damage, and use them to estimate the radiation protection quantity dose equivalent. A prototype instrument utilizing a spherical proportional counter and a microcomputer to make such measurements has been developed and tested. The detector is filled with gas at low pressure in order to simulate micrometer diameter volumes of tissue. Energy deposition in these small volumes is a stochastic quantity which depends on charged particle stopping power, path length through the site, energy loss straggling, and energy transport by secondary charged particles (delta rays). To the extent that the energy deposition in the site is proportional to the geometric chord length distribution, energy deposition can be used to determine the linear energy transfer. The mean quality factor can then be calculated on the basis of the current definition. The prototype instrument uses two amplifiers, with gains of 50 and 1000, processing the pulses from a single detector in order to resolve the wide range of energy deposition events produced by neutron and gamma irradiation. Each amplifier is connected to a specially designed analog to digital converter and a 128 channel multichannel analyzer. A microcomputer controls the system and calculates dose and dose equivalent. Test results for a variety of accelerator produced neutron irradiations show that, from 0.1 to 15 MeV, system accuracy is +-0.5 for anti Q and +-15% for dose equivalent. 9 references, 3 figures, 2 tables.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6340686
- Report Number(s):
- PNL-SA-12407; CONF-841117-23; ON: DE85003636
- Resource Relation:
- Conference: 8. conference on the application of accelerators in research and industry, Denton, TX, USA, 12 Nov 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
Similar Records
Principles of microdosimetry in radiation protection
Develop real-time dosimetry concepts and instrumentation for long-term missions
Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
DOSE EQUIVALENTS
MICRODOSIMETRY
PROPORTIONAL COUNTERS
DESIGN
ENERGY TRANSFER
LET
QUALITY FACTOR
RADIATION QUALITY
DOSIMETRY
MEASURING INSTRUMENTS
RADIATION DETECTORS
655003* - Medical Physics- Dosimetry
440102 - Radiation Instrumentation- Radiation Dosemeters