TITLE:
Quality Assurance in SPECT/CT for Radionuclide Therapy with Lutetium-177
AUTHORS:
Olivia Adu-Poku, Eric Kotei Addison, Bright Kwakye-Awuah, Stephen Inkoom, Francis Hasford, Cletus Ahadzie, Joseph Adom, Isaac Kojo Wilson
KEYWORDS:
Lutetium-177, Activity Concentration, Dose Calibrator, SPECT/CT
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.11 No.1,
February
24,
2022
ABSTRACT: This study was done to quality assure the Hawkeye
SPECT/CT at the St. Olav’s hospital and create a clinical method for
doing individual dosimetry with 177Lu-octreotate
in targeted radionuclide therapy for neuroendocrine tumors. Various quality control
parameters were performed on Infinia Hawkeye SPECT/CT. A calibration dose of
160% ± 2% MBq was ordered and first
calibrated for all the dose calibrators. The uniformity test was obtained using
a 40 MBq Tc-99m point source positioned 2.5 m away from the two detectors. A 200 MBq Tc-99m was diluted in 70 ml of
water, dispersed in six syringes for the registration test. A Lu-177
point source
was placed in front of the detectors, one at a time, to check
the energy peaks. The Jaczczak phantom with a hollow sphere set (volumes: 0.5, 1, 2, 4, 8, and 16)
ml with an additional 60 ml sphere was used for the 3D sensitivity and recovery
with Lu-177. Total activity of 945.3 MBq was added to 160 ml of water yielding an activity concentration of 5.908 MBq/ml
in the spheres. The phantom was then scanned at various time intervals. A
cylindrical phantom with a volume of 6283 ml was also used to obtain the
cross-calibration measurement (cps/MBq). Total activity of 995.6
MBq was added and the phantom was scanned at days 0, 6, 13 and 23. The
dose calibration factor was changed from 762 to 760 to achieve correct doses. The 2D mean sensitivity factor was 5.56
cps/MBq. Uniformities for both detectors were approved after
iteration calibration of the PM tubes. The X-ray to SPECT registration
was found to be accurate and within specifications. The energy peak test revealed off-centered 208 keV energy peaks for
the two detectors. Quality assurance of imaging devices using radiation
is essential for radiation protection and ensures a high-quality image.