Tailoring 99mTc-Macroaggregated Albumin Administration to Optimize Patient Dose Reduction.
In the ever-changing field of nuclear medicine, best-practice considerations cannot simply go unchallenged for months and years, with the need to minimize radiation exposure to patients highlighted in "as low as reasonably achievable" principles. The Australian Radiation Protection and Nuclear Safety Agency reports that the dose for (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) administered should be 180-200 MBq. An objective of imaging in pulmonary embolism, or indeed any diagnostic procedure involving radiation, is to minimize radiation exposure without sacrificing image quality and diagnostic accuracy. The amount of radiation involved must be considered together with imaging protocols. Our aim was to reduce the amount of (99m)Tc-MAA administered without compromising the diagnostic quality of the scan.


METHODS
To achieve a ventilation-to-perfusion ratio of 1:4, we ventilated the patient as per standard protocol and then placed intravenous access into the patient. For the perfusion component, 180-200 MBq were prepared in a 2-mL injection. Aliquots of 0.5 mL of (99m)Tc-MAA were administered every 30 s followed by a 5-mL saline flush until the required ventilation-to-perfusion ratio was achieved.


RESULTS
With this protocol, the average administered dose was 105 ± 20.7 MBq (vs. 180 ± 5.3 MBq, P < 0.0001).


CONCLUSIONS
By individually tailoring the administered dose, diagnostic quality is maintained while achieving a significant dose reduction.
Department of Nuclear Medicine, St. F.X. Cabrini Hospital, Malvern, Victoria, Australia; and.
Sarah L
SL
Gales
Department of Nuclear Medicine, St. F.X. Cabrini Hospital, Malvern, Victoria, Australia; and.
Sharn K
SK
Peters
Department of Nuclear Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Nouria
N
Salehi
Department of Nuclear Medicine, St. F.X. Cabrini Hospital, Malvern, Victoria, Australia; and Department of Nuclear Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia nathan.better@mh.org.au.
Nathan
N
Better
D065638:Absorption, Radiation; D000280:Administration, Inhalation; D000328:Adult; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D000069079:Radiation Exposure / Q000032:analysis / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000008:administration & dosage*; D013668:Technetium Tc 99m Aggregated Albumin / Q000008:administration & dosage*; D017971:Tin Compounds / Q000008:administration & dosage*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014692:Ventilation-Perfusion Ratio
D019275:Radiopharmaceuticals; D012709:Serum Albumin; D013668:Technetium Tc 99m Aggregated Albumin; D017971:Tin Compounds; C038216:technetium Tc 99m-Sn aggregated albumin
MAA; VQ scan; dose reduction