Researchers at the Medical University of Vienna/AKH Vienna, Austria, say that they have been able to demonstrate that the use of helium ions in radiation therapy could provide accurate treatment to tumors while helping to spare healthy organs. A treatment planning study presented at European Society for Radiotherapy & Oncology (ESTRO) Congress 33 in April showed that helium may provide effects superior to radiotherapy using protons, which are already a considerable advance on conventional photon beam radiotherapy.
The researchers set out to devise a method of calculating the optimal dose of helium ions for use in radiation treatment. The dose calculation algorithm was then used for treatment plan calculation for ten pediatric patients, five with neuroblastoma, and five with Hodgkin’s lymphoma.
“Helium ions may represent another kind of particle that can improve radiotherapy treatment. Due to their increased mass, spreading of the beam is reduced by a factor of two as compared with protons. Moreover helium ions have an increased biological effectiveness at the end of their range,” explained Hermann Fuchs, a PhD student.
Heavier ions like carbon have the potential to kill cancer cells more effectively due to their underlying biology. But by modeling these biological processes, large uncertain ties are introduced, and these can be reduced by using lighter ions like helium. “Helium ions reside in the low Linear Energy Transfer (LET) area,” said Fuchs. “LET is a physical quantity describing how much energy of a particle is deposited at a given range, and this measure is important when looking at the biological effects of therapy.” (See Figure 1)
This greater accuracy and sparing of normal tissue is very important in the case of children, the researchers say. When treating them it is particularly important to ensure that as little dose of radiation as possible is deposited outside the area to be treated, since an increased area treated with a low dose can lead to the development of secondary cancers. Given that children have a potentially long lifespan ahead of them, this probability needs to be reduced as much as possible through the use of therapies that are targeted as accurately as possible to the tumor, while sparing the dose to surrounding areas, and especially to healthy organs particularly sensitive to radiation located nearby.
Their treatment planning algorithm enabled them to investigate the possibilities for using helium ion therapy in children treated with low dose radiation. They next plan to investigate its potential in patients being treated with higher doses, Fig. 1 – Visible spectrum of helium. (Credit: NASA) for example, those with brain tumors.