Award-winning technology enhances advanced radiation therapy

A health researcher at the Australian Nuclear Science and Technology Organisation (ANSTO) has been recognised for her contribution to a new hybrid technique that enhances the effectiveness of a special form of radiation therapy for cancer treatment.

Particle therapy is a technologically advanced form of radiation therapy that precisely delivers energy to destroy tumours with minimal side effects. Neutron Capture Enhanced Particle Therapy (NCEPT) involves injecting a patient with a neutron capture agent shortly before irradiation with protons or heavy ions — an approach which boosts the target dose without increasing the dose to healthy tissue and delivers a significant dose to secondary lesions outside the primary treatment area.

Dr Mitra 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,” said Dr Safavi-Naeini. “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.”

Simulations show that in some tissues, current drugs can deliver a benefit of the order of 5–10%; 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 by ANSTO.

“We are excited about the simulation data, which suggests that the thermal neutron dose could reach a target up to 14 cm deep,” said Dr Safavi-Naeini. “This means you have the possibility of reaching deep-seated tumours.

“It may be beneficial to radiation-resistant tumours, neuroblastomas in children or a way of treating secondary lesions in the brain.”

The two isotopes used in the neutron capture agent are boron-10 and gadolinium-157. 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 Dr Safavi-Naeini.

Dr Safavi-Naeini was last year selected as a recipient of the Union for International Cancer Control (UICC) and the UICC Japan National Committee Yamagiwa-Yoshida Memorial international Cancer Study Grant Fellowship, which allows her to gain additional proof-of-concept evidence at the National Institute of Radiological Science in Chiba, Japan. The fellowship will allow her to test the drug with cancer cells that are irradiated with and without the presence of neutron capture drugs and compare their survival rates against control cells.

More recently, Dr Safavi-Naeini received a 2018 Fraunhofer Innovation Award from the German Embassy, which will enable her to carry out proof-of-concept experiments at German particle therapy centres later this year. She and her colleagues have also successfully applied to the ON Prime Program, which assists researchers in accelerating concepts to market delivery.