SONOGRAPHERS AND EXPOSURE TO IONISING RADIATION FROM NUCLEAR MEDICINE PATIENTS

Julia Janssen, Nuclear Medicine Technologist, Richard Smart, Principal Physicist, Erin McKay, Senior Physicist, Department of Nuclear Medicine, St George Hospital Kogarah NSW

Abstract
Occasionally, patients may require both nuclear medicine procedures and ultrasound examinations on the same day. In keeping with the ALARA principle (as low as reasonably achievable) the nuclear medicine investigation should preferably be performed after the other studies, this ensuring that the sonographer does not receive unnecessary radiation exposure. However there are clinical circumstances in which an ultrasound examination is required on a patient who has already been injected with a radiopharmaceutical. This study examined the potential radiation exposure to the sonographer and measured the actual exposure received in a busy teaching hospital.

For each of five common nuclear medicine procedures (bone, lung, biliary, myocardial perfusion and gallium) the external dose rates were measured at distances ranging from zero to 100 cm from ten patients, at four time points up to 24 hours post injection. Additional measurements at 72 hours were made for those patients administered ⁶⁷ Ga. The results indicate that the sonographer could potentially receive an external dose in the range 6-28 µSv, although in practice, no radiation exposure was detected from the 4 nuclear medicine patients scanned in the ultrasound department during a 5 week period. These results reinforce the advice from the NSWW Health Department that a prior administration of a radiopharmaceutical is not, in itself, a contraindication to performing an ultrasound examination.

Citation
Janssen J, Smart R, McKay E. Sonographers and exposure to ionising radiation from nuclear medicine patients. ASUM Bulletin 2000.3:4-8.