Prompt gamma tomography for BNCT-SPECT: a feasibility study using small animal phantoms

Boron Neutron Capture Therapy (BNCT) is a binary radiotherapy based on the reaction
¹⁰
B(n,α)
⁷
Li induced by thermal neutrons.
¹⁰
B selectively loads cancer cells through a boronated drug injected into patient few hours before neutron irradiation. The secondary charged particles have short ranges in tissues (less than the mean cell diameter of few tens of μm), thus they deposit their whole kinetic energy (up to 2.79 MeV) inside the cell where the capture reaction took place. In this way it is possible to selectively damage the malignant cells sparing the surrounding healthy ones.To take full advantage of BNCT selectivity a precise knowledge of
¹⁰
B spatial distribution is required. This quantity can be measured by Single Photon Emission Computed Tomography (SPECT) thanks to the emission of a 478 keV γ ray in the 94% of
¹⁰
B capture reactions. Notably, the counting rate of this photon is meaningful of the dose rate due to the neutron captures in the patient thus allowing an in vivo, real time dose monitoring.In the present study we evaluated the capabilities of a small prototype of CdZnTe (CZT) photon detector to reconstruct the tomographic image of tissue equivalent phantoms loaded with point like γ sources (such as
²²
Na,
¹³⁷
Cs and
⁵⁷
Co), activated detectors (Cu and Au wires) and
¹⁸
F water solutions.