Computed radiography as a gamma ray detector--dose response and applications

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiography Technology

Background:

• Computed radiography (CR) offers a wide dynamic range and good response to medium-energy gamma rays, potentially reducing exposure times.
• Unlike screen-film systems, CR does not require pre-sensitization via X-ray exposure for low-dose measurements.
• CR plates exhibit sensitivity to gamma ray emissions from radionuclides.

Purpose of the Study:

• To evaluate the utility of computed radiography (CR) for imaging photon emissions from radionuclides.
• To assess the performance of CR plates (Agfa MD30, Kodak GP25) with technetium-99m and iodine-131.
• To investigate potential artifacts, such as X-ray fogging, in nuclear medicine patients due to CR plate sensitivity.

Main Methods:

• Utilized cassette-based Agfa MD30 and Kodak GP25 CR plates.
• Applied CR for detecting gamma ray emissions from technetium-99m and iodine-131.
• Examined image quality at low cassette entrance doses (e.g., 1 microGy at 140 keV).

Main Results:

• CR imaging successfully detected gamma ray emissions from technetium-99m and iodine-131.
• Images obtained with low doses (1 microGy) were noisy but suitable for detecting radiation protection barrier integrity.
• A diffuse fogging effect on X-rays was observed in nuclear medicine patients if imaging occurred shortly after radiopharmaceutical injection.

Conclusions:

• Computed radiography is a viable tool for imaging radionuclide spatial distribution, particularly for low-dose applications and barrier integrity checks.
• The gamma ray sensitivity of CR plates necessitates consideration of potential X-ray fogging in nuclear medicine patients.
• Further investigation into managing or mitigating this diffuse fogging is warranted.