Modern dosimetric tools for ⁶⁰Co irradiation at high containment laboratories

Abstract

Purpose: To evaluate an innovative photo-fluorescent film as a routine dosimetric tool during ⁶⁰Co irradiations at a high containment biological research laboratory, and to investigate whether manufacturer-provided chamber exposure rates can be used to accurately administer a prescribed dose to biological specimens.

Materials and methods: Photo-fluorescent, lithium fluoride film dosimeters and National Institutes of Standards and Technology (NIST) transfer dosimeters were co-located in a self-shielded ⁶⁰Co irradiator and exposed to γ-radiation with doses ranging from 5–85 kGy. Film dose-response relationships were developed for varying temperatures simulating conditions present when irradiating infectious biological specimens. Dose measurement results from NIST transfer dosimeters were compared to doses predicted using manufacturer-provided irradiator chamber exposure rates.

Results: The film dosimeter exhibited a photo-fluorescent response signal that was consistent and nearly linear in relationship to γ-radiation exposure over a wide dose range. The dosimeter response also showed negligible effects from dose fractionization and humidity. Significant disparities existed between manufacturer-provided chamber exposure rates and actual doses administered.

Conclusion: This study demonstrates the merit of utilizing dosimetric tools to validate the process of exposing dangerous and exotic biological agents to γ-radiation at high containment laboratories. The film dosimeter used in this study can be utilized to eliminate potential for improperly administering γ-radiation doses.

Keywords::

• Microbiology
• radiation chemistry
• radiation physics
• dose-response curve
• dosimetry
• radiation