Comparison between Three Promising ß-emitting Radionuclides, 67Cu, 47Sc and 161Tb, with Emphasis on Doses Delivered to Minimal Residual Disease

Christophe Champion, Michele A. Quinto, Clément Morgat, Paolo Zanotti-Fregonara, Elif Hindié
Theranostics. 2016-01-01; 6(10): 1611-1618
DOI: 10.7150/thno.15132

Lire sur PubMed

1. Theranostics. 2016 Jun 18;6(10):1611-8. doi: 10.7150/thno.15132. eCollection

Comparison between Three Promising ß-emitting Radionuclides, (67)Cu, (47)Sc and
(161)Tb, with Emphasis on Doses Delivered to Minimal Residual Disease.

Champion C(1), Quinto MA(1), Morgat C(2), Zanotti-Fregonara P(2), Hindié E(2).

Author information:
(1)1. Université de Bordeaux, CNRS/IN2P3, Centre d’Etudes Nucléaires de Bordeaux
Gradignan (CENBG), France;
(2)2. Service de Médecine Nucléaire – CHU de Bordeaux; UMR-CNRS 5287; LabEx
TRAIL; Université de Bordeaux, FRANCE.

PURPOSE: Radionuclide therapy is increasingly seen as a promising option to
target minimal residual disease. Copper-67, scandium-47 and terbium-161 have a
medium-energy β(-) emission which is similar to that of lutetium-177, but offer
the advantage of having diagnostic partner isotopes suitable for pretreatment
imaging. The aim of this study was to compare the efficacy of (67)Cu, (47)Sc and
(161)Tb to irradiate small tumors.
METHODS: The absorbed dose deriving from a homogeneous distribution of (67)Cu,
(47)Sc or (161)Tb in water-density spheres was calculated with the Monte Carlo
code CELLDOSE. The diameters of the spheres ranged from 5 mm to 10 µm, thus
simulating micrometastases or single tumor cells. All electron emissions,
including β(-) spectra, Auger and conversion electrons were taken into account.
Because these radionuclides differ in electron energy per decay, the simulations
were run assuming that 1 MeV was released per µm(3), which would result in a dose
of 160 Gy if totally absorbed.
RESULTS: The absorbed dose was similar for the three radionuclides in the 5-mm
sphere (146-149 Gy), but decreased differently in smaller spheres. In particular,
(161)Tb delivered higher doses compared to the other radionuclides. For instance,
in the 100-µm sphere, the absorbed dose was 24.1 Gy with (67)Cu, 14.8 Gy with
(47)Sc and 44.5 Gy with (161)Tb. Auger and conversion electrons accounted for 71%
of (161)Tb dose. The largest dose differences were found in cell-sized spheres.
In the 10-µm sphere, the dose delivered by (161)Tb was 4.1 times higher than that
from (67)Cu and 8.1 times that from (47)Sc.
CONCLUSION: (161)Tb can effectively irradiate small tumors thanks to its decay
spectrum that combines medium-energy β(-) emission and low-energy conversion and
Auger electrons. Therefore (161)Tb might be a better candidate than (67)Cu and
(47)Sc for treating minimal residual disease in a clinical setting.

DOI: 10.7150/thno.15132
PMCID: PMC4955060
PMID: 27446495 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus