Radiological safety in application of radiation in medicine

Positron Emission Tomography (PET)  is used as an imaging technique in a wide range of biomedical research applications in human patients and volunteers. Millions of PET scans are performed worldwide. Radio-tracer is introduced to the patient and its movement or deposition in the body is followed through a PET scan. A typical nuclear medicine procedure results in a radiation dose of around 25 mSv to a patient, while a CT scan using X-rays gives a dose of 5-8 mSv per scan, depending on which part of the body is scanned. To put risks in a proper perspective, natural background radiation dose is in the range of 2 to 3 mSv in year.

Radiation protection principle recommends optimization of the procedure to minimise patient dose. Some of possible ways of minimization of the dose is:

Ø Use highly sensitive and faster scanners for the procedure so that time spent is minimum for scanning so that the system can detect and perform scans at very low levels of emissions

Ø Optimise the radio-tracer dose to the patient to get a good scan

Ø Select a most suitable short-lived low energy photon emitting radiotracer

Ø Minimise radiation exposures of the healthy tissues/organs which are adjacent to the tissue/organ being scanned or treated. 

  

The procedures results in radiation dose (occupational exposures) to the medical, para-medical staff and technicians who are handling the radioactive material and who operate the machines for scanning. Scattered radiation from the primary beam is of concern, particularly to the eye lens, and needs to be monitored. Suitable radiation dosimetry technique should be used for the purpose. The hospital health physicist should ensure that the occupational exposures should be controlled and kept as low as reasonably achievable (ALARA).

Finally, the hospitals, the physicians/radiologist should avoid misuse of this technology for financial gains alone. In addition to the benefits to the patient from the procedure, the patients should be thoroughly briefed about the possible health effects from the exposure to radiation. Benefits should outweigh the risks of the exposures.