Speaker
Description
Authors: Marco Capogni 1,*, Aldo Fazio 1, Maria Vaccaro 2 and Pierino De Felice 1
Affiliation:
1 Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (INMRI)-ENEA
C.R. Casaccia - Via Anguillarese 301 I-00123 Roma, Italia;
2 University of Rome “La Sapienza”- Department of Physics – P.le Aldo Moro 2, I-00185, Rome, Italy
Holmium-166 is a radionuclide of interest in medical treatments both for diagnostics (imaging) and therapeutic applications thanks to its peculiar decay scheme characterized by beta and gamma emissions with the main gamma-ray of 80.5725(13) keV which makes it suitable for SPECT (Single Photon Emission Computed Tomography) diagnosis. In recent therapy, tiny particles called microspheres filled with 166Ho are delivered directly to the tumour site by a catheter. The main gamma-ray can be used to monitor by SPECT the delivery of the 166Ho radiopharmaceutical to the location of the cancer in the organs, in particular for treatment of liver diseases. This radionuclide has also paramagnetic properties that makes it possible to be used in magnetic resonance imaging (MRI).
The Italian National Institute of Ionizing Radiation Metrology (INMRI) belonging to ENEA, and located in the Casaccia Research Centre near Rome, developed before the covid-19 pandemic a primary standard of 166Ho by using the absolute technique of Triple-to-Double Coincidence Ratio (TDCR). The 166Ho absolute gamma emission intensities were obtained by high energy resolution gamma-ray spectrometry performed on the ENEA-INMRI HPGe detector calibrated by the new 166Ho standard and also by other ENEA-INMRI gamma-emitter standards. The new set of gamma emission intensities, Igamma, for 166Ho was then compared with the values published in the literature. The new set was also communicated to the DDEP (Decay Data Evaluation Project) Working Group to improve the quality of nuclear data for such kind of radionuclide.
