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摘要
Objective: To develop an alpha dosimetry technique for activity calibration of alpha-emitting radiopharmaceuticals using the Gafchromic (R) EBT3 (Gaf-EBT3) radiochromic film (International Speciality product, Wayne, NJ). Methods: The Gaf-EBT3 has a tissue equivalent radiosensitive layer (approximately 28 mu m) sandwiched between two 100-mu m thick polyester sheaths, thereby making it insensitive to alpha particles. We have split a Gaf-EBT3 sheet using a surgical scalpel to remove one of the polyester protective layers and covered the radiosensitive layer with thin Mylar (R) foil (Goodfellow Cambridge Limited, Huntingdon, UK) (2.5 mu m). Small pieces of modified film were exposed at contact with a 560-Bq thin Am-241 source for 5, 10, 24 and 94h. The optical density of the films was evaluated using an optical densitometer. The alpha energy spectra of the 241Am source were recorded using a Si(Li) surface barrier detector. Results: Time-integrated specific alpha surface activity (kBqcm(-2)h) was represented as a function of optical density. Conclusion: By removing one of the 100-mu m thick polyester protective layers, the authors have modified the Gaf-EBT3 film to a sensitive alpha dosemeter. The calibration function relevant to a Am-241 reference source was evaluated from the optical densities of the dosemeter foils. Furthermore, calibration functions for important alpha emitters such as Ra-223, Ac-225 or Bi-210 were parameterized from the Am-241 reference data. Advances in knowledge: The authors have developed and tested the principle of a clinical alpha dosemeter using Gaf-EBT3 radiochromic films originally developed for photon dosimetry. This novel, user-friendly technique could be implemented in quality assurance and calibration procedures of important alpha-emitting radiopharmaceuticals prior to their clinical applications.
- 出版日期2015
