Neutron Capture Enhanced Particle Therapy (NCEPT) involves injecting a patient with a neutron capture agent shortly before irradiation with proton or heavy ion therapy.
The approach boosts the target dose without increasing the dose to healthy tissue and delivers a significant dose to secondary lesions outside the primary treatment area.
ANSTO has acquired a provisional patent for the NCEPT method.
Particle therapy, a technologically advanced form of radiation therapy that precisely delivers energy to destroy tumours with minimal side effects, will soon be available in Australia. The first proton therapy facility is now under construction in South Australia, and ANSTO is among a group of organisations advocating for the establishment of a national heavy ion treatment and research facility.
Safavi-Naeini and PhD student Andrew Chacon of the University of Wollongong (UOW) developed the concept while estimating the quantity of thermal (low-energy) neutrons produced as a by-product of particle therapy. These neutrons are produced when the protons or heavy ions collide with tissues in the body, which sometimes result in nuclear fragmentation.
The thermal neutrons that are produced with particle therapy do not stay localised to the target volume.
“We thought that because there already are several tumour-specific drugs that can capture neutrons, we could administer them to patients prior to particle therapy. The neutron capture process releases more energy inside the tumour, where it is beneficial, and reduces the neutron dose to healthy tissues around the treatment site,” said Safavi-Naeini.
Simulations show that in some tissues, current drugs can deliver a benefit of the order of 5-10 per cent – however, newer drugs currently under development may offer even greater enhancement.
Preliminary experiments and simulations to date have been most encouraging, allowing the acquisition of a provisional patent.
There are a number of innovative aspects to the therapy.
The two isotopes used in the neutron capture agent are boron-10 and gadolinium-157.
“We are excited about the simulation data, which suggests that the thermal neutron dose could reach a target up to 14 centimetres deep. This means you have the possibility of reaching deep-seated tumours,” said Safavi-Naeini.
“It may be beneficial to radiation-resistant tumours, neuroblastomas in children, or a way of treating secondary lesions in the brain.”
Because gadolinium is also a contrast enhancement agent for imaging purposes, it also opens up the possibility of vertical integration in treatment.
“We could go from pre-treatment through to post-treatment using the same agent to guide treatment planning, monitor treatment quality and evaluate its effectiveness,” said Safavi-Naeini.