RT Journal Article
SR Electronic
T1 Patient-Specific Radiation Dosimetry of <sup>99m</sup>Tc-HYNIC-Tyr<sup>3</sup>-Octreotide in Neuroendocrine Tumors
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1474
OP 1481
DO 10.2967/jnumed.111.088203
VO 52
IS 9
A1 Grimes, Joshua
A1 Celler, Anna
A1 Birkenfeld, Bozena
A1 Shcherbinin, Sergey
A1 Listewnik, Maria H.
A1 Piwowarska-Bilska, Hanna
A1 Mikołajczak, Renata
A1 Zorga, Piotr
YR 2011
UL http://jnm.snmjournals.org/content/52/9/1474.abstract
AB 99mTc-hydrazinonicotinamide-Tyr3-octreotide (99mTc-HYNIC-TOC) is increasingly gaining acceptance as a new radiopharmaceutical for the diagnosis of pathologic lesions overexpressing somatostatin receptors. However, little information has been published about the radiation dosimetry of this agent. The aim of this study was to assess the biodistribution and radiation dosimetry of commercially available 99mTc-HYNIC-TOC. A dose calculation procedure designed to be feasible to implement in a busy clinical environment was used. Methods: Twenty-eight patients were imaged for suspected neuroendocrine tumors using a series of whole-body planar, dynamic planar, and SPECT/CT studies, after injection with 99mTc-HYNIC-TOC. Patient-specific dosimetry was performed using the OLINDA/EXM software with time-integrated activity coefficients estimated from a hybrid planar/SPECT technique. A phantom experiment was performed to establish adaptive thresholds for determination of source region volumes and activities. Results: Pathologic uptake, diagnosed as due to neuroendocrine tumors, was observed in 12 patients. Normal organs with significant uptake included the kidneys, liver, and spleen. The mean effective dose after 99mTc-HYNIC-TOC injection was 4.6 ± 1.1 mSv. Average normal-organ doses were 0.030 ± 0.012, 0.021 ± 0.007, and 0.012 ± 0.005 mGy/MBq for the spleen, kidneys, and liver, respectively. The interpatient kidney dose ranged from 0.011 to 0.039 mGy/MBq, whereas the range of tumor doses varied from 0.003 to 0.053 mGy/MBq. The ratio of tumor to kidney dose ranged from 0.13 to 2.9. The optimal thresholds for recovery of true activity in the phantom study were significantly lower than those used for volume determination. Conclusion: The patient-specific 3-dimensional dosimetry protocol used in this study is a clinically feasible technique that has been applied to demonstrate large dose variations in tumors and normal organs between patients imaged with 99mTc-HYNIC-TOC.