Argentina and its advances in nuclear medicine: a revolution in the treatment of complex tumors

A group of researchers from the Constitucióntes Atomic Center, led by Dr. Andrés Kreiner, is developing a particle accelerator for the treatment of cancer through neutron capture therapy in boron.

There are some types of cancer that cannot be treated with conventional radiotherapy. To treat these types of tumors, diffuse, infiltrative or even those more resistant to gamma radiation, Dr. Andrés Kreiner and his team are venturing into a very effective treatment, which is dominated only by a handful of countries: neutron capture therapy. in boron (BNCT).

Dr. Kreiner, nuclear physicist, leads the "Accelerators for Life" program at the National Atomic Energy Commission (CNEA). The goal is to develop and install a particle accelerator manufactured entirely in our country. They already have a modular machine, installed at the Constituent Atomic Center, and in 2022 they will export that technology to the Korean Institute of Radiology and Medical Sciences (KIRAMS), based in Seoul.

A treatment with a high degree of precision

As a general principle, the ionizing radiation used in radiotherapy aims to destroy the DNA of the tumor cell, which is the molecule that transmits genetic information. "Those radiotherapy techniques where a beam of photons or protons falls directly on the patient are useful when the tumors are well delimited and geometrically defined," he said.

However, he explained: "There are other types of tumors in which tumor cells invade a volume of healthy tissue. They are disparate cells and there is no way to target them because there is still no way to have a map at the cellular level that allows the beam of rays to be targeted. cells per cell."

In dialogue with DEF, Kreiner provided details of the new type of treatment, which is still in the experimental phase.

-How does boron neutron capture therapy (BNCT) work?

-BNCT is a much more sophisticated methodology, which has two steps. The first step consists of selectively "doping" the tumor cells with a molecule whose structure contains an isotope with the ability to capture neutrons. There are very few substances in nature with that capacity. One of these substances is boron 10. We need, then, a sufficiently selective drug that has boron 10 in its molecular structure. Today there is a drug, borophenylalanine (BPA), that has been authorized by the Food Administration. and US Medicines and other similar institutions. This drug concentrates 3.5 times more boron 10 in tumor cells than in healthy cells. Due to their different metabolism, cancer cells absorb more of this drug, which is administered intravenously. You have to wait about two hours until the drug concentrates in the tumor tissue.

-What is the second step?

-Once we have the patient in that condition, they are irradiated with neutrons. Neutrons interact with boron 10. How does this interaction occur? Boron 10 captures a neutron and an ephemeral, highly excited nucleus of boron 11 is generated, which splits into two highly ionizing particles. The microexplosion that occurs in this interaction damages only the cell where the boron 10 is concentrated and preserves the surrounding healthy tissue. That is one of the crucial issues of radiotherapy: destroying the tumor, damaging the surrounding tissue as little as possible.

From reactors to accelerators

-Why is it necessary to build an accelerator in our country?

-Boron neutron capture therapy (BNCT) began to be developed at the base of the reactors. At RA-6, at the Bariloche Atomic Center, a clinical research program was carried out that was very successful. However, a strong limitation in this type of treatment is the need to transfer patients to a reactor, in a nuclear center, which is not a hospital and is not prepared for that. That is where accelerators appear as an alternative, allowing neutron sources to be installed in hospitals.

-How do particle accelerators work?

-They are electrical machines that are used to accelerate particles. The simplest technology is electrostatic technology, which is what we master. What we are looking for at CNEA is to develop our own technology. A few years ago, we launched the idea of ​​developing our own accelerator, with significant relative success. We have developed a modular machine, with modules on the order of 120,000 volts. These modules are stacked and, in this way, we add tension. Approximately 1.5 million volts are needed to accelerate the particles that will then impact a target and produce the neutrons that will be used for this therapy.

-What was exported to South Korea? How did you become interested in the Argentine accelerator?

-The accelerator was conceived and developed in our country, with minor imported components. We sold a single-module accelerator prototype to an institute in South Korea. In 2019 they invited me to go to Korea, where a two-day workshop was held. KIMARS is a research and development institute and did not want to buy a "turnkey" machine where there was nothing to develop. They opted for our machine and we signed a technological innovation contract. We traveled to Korea and installed the machine in that institute. At the end of 2022, we successfully terminate the contract.

The competitive advantages of the Argentine model

"We are concentrating on producing an electrostatic machine with the lowest possible energy, which means lower cost, and that does not produce residual radioactivity, which is the big problem with reactors," details the person responsible for the "Accelerators for Life" project. Looking to the future, he assures, "it is important to finish the project not only because it will allow us to satisfy our own needs, but it is also an export object, as we already demonstrated."

To advance the project, a specific laboratory for the development of accelerator technology is currently being built, which in the future should also serve as a center for the development of boron neutron capture therapy (BNCT).

Beyond their application in BNCT, today accelerators complement reactors due to their capacity to produce large neutron fluxes. "One of its most promising applications is the production of radioisotopes," explains Kreiner. Among them, he mentions technetium-99, one of the radioisotopes most used in radiodiagnosis and which today is only produced in reactors.

"The cost of an accelerator is much lower than that of a reactor. Being much simpler from the point of view of radiological protection, obtaining a license for such a facility is much simpler," he summarizes. In that sense, the Nuclear Regulatory Authority (ARN) authorized the construction of the building at the Constituent Atomic Center as the so-called "non-routine practice" in the accelerator.

On the other hand, within the framework of the "Innovate" competition of the former Ministry of Science and Technology, the "Accelerators for Health" project won a prize in the "Innovative Design" category in 2023 and was also awarded the "Great Innovate Distinction." ". Unfortunately, the State still owes them the full amount of $2,000,000 for both awards. "It was recognition of our work by a specialized jury. It was an important boost and supports us to move forward," concludes Kreiner, who sees the future of the project with optimism..

By: Mariano Roca - Fuente: DEF