Program Information
Dose Estimation of 18F-FDG in Breast During PET/CT Scans: A Monte Carlo Study
M Fallahpoor1*, P Geramifar2 , M Ebrahimi3 , F Kalantari4 , (1) Tehran University of Medical Sciences, Tehran, Iran, (2) Research Center for Nuclear Medicine, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran, (3) Department of Nuclear Medicine, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran, (4) UT Southwestern Medical Center, Dallas, TX
Presentations
TU-L-GePD-IT-3 (Tuesday, August 1, 2017) 1:15 PM - 1:45 PM Room: Imaging ePoster Theater
Purpose: Breast is a target for FDG accumulation and one of the most critical organs in terms of radiation concerns. FDG absorption is highly dependent on estrogen hormone levels which varies by age and time point during the menstrual cycle. With increasing the age, the level of the female hormones and therefore breast activity decreases, hence FDG absorption in older patients becomes low. In this Monte Carlo study we measured the self-absorbed dose of the breast in two young and middle-aged patients.
Methods: 18F-FDG PET/CT scans of two patients were studied. The attenuation corrected PET images were used as a biodistribution of activity and the CT images as anatomical data. PET scans were performed in 3 bed positions. Images were corrected for attenuation and scatter and stored in a 128 × 128 matrix for reconstruction. Fusion of the PET and CT images were done by Siemens Simbia-T software. Organ segmentation was performed by itk-SNAP to define regions of interests (ROIs). GATE Monte Carlo Simulator was employed for internal dosimetry. S-values (mGy/MBq.s) for self-absorption of breast and heart were calculated.
Results: We observed significant amount of absorbed dose in the breasts of the 19-year old patient (1.23e-04 mGy/MBq.s). This value is comparable with absorbed dose in the heart (2.66e-04 mGy/MBq.s) that is a high glucose consumer and therefore the optimum target for FDG. The absorbed dose in the 44-year old patient is 5.08e-005 mGy/MBq.s which is considerably lower than that of the younger patient.
Conclusion: The results showed considerable breast absorbed dose in the younger patient. Given the fact that many patients who are prescribed 18F-FDG PET/CT scan are young, estimation of absorbed dose in breast should be taken into account by physicians to reduce breast cancer risk.
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