Radiation dose levels associated with a PET and PET/CT suite in a nuclear medicine department

Objectives Our department has recently expanded PET and PET/CT modalities to include PET Rb-82 cardiac imaging. With the new imaging modality and increase in patient volume, a study was conducted to assure compliance to ALARA standards.

Methods Two studies were conducted over a four week time interval. In the initial study, 19 radiation monitoring devices (optically stimulated luminescent dosimeters) were strategically placed throughout the PET and PET/CT imaging center as well as ancillary areas. In the second study, 9 radiation monitoring devices were placed in the PET and PET/CT imaging suites only. Control monitoring device were utilized. Following each study, radiation devices were collected and sent to Landauer Inc. for analysis. The total number of patient scans performed in the study was documented.

Results The number of PET (Rb-82) and PET/CT scans performed during the study interval was 52 and 181, respectively. In the initial study, minimal radiation levels were detected in the PET imaging suite, the PET and PET/CT control areas, surrounding hallways and adjacent offices. Radiation readings of 6 mrem and 127 mrem were detected in the PET/CT imaging suite on parallel walls. The second study confirmed minimal radiation levels in the PET suite and PET/CT control areas as well as high radiation readings of 32 mrem and 124 mrem in the PET/CT imaging suite. Analysis of radiation quality indicated photon energies ranging from less than 40 keV up to 200 keV consistent with CT scatter radiation.

Conclusions Radiation levels in a PET and PET/CT suite and associated areas were monitored over a 4-week time period. Significant radiation levels were detected in the restricted PET/CT imaging suite corresponding to CT scatter radiation