07 marzo 2013

Onde millimetriche (30-300 GHz), una possibile applicazione sanitaria?

Risultati inaspettati sono stati presentati dai ricercatori israeliani dell'Ariel University Center alla conferenza IEEE Conference on Microwaves,  Communications, Antennas and Electronic Systems (Comcas) in programma in questi giorni a Tel Aviv. Sembra che gli scienziati abbiano osservato un effetto di inibizione delle cellule tumorali dopo l'applicazione di onde millimetriche, cioè su frequenze comprese tra i 30 e i 300 GHz. Come viene spiegato nel comunicato curato dal Ministero degli esteri israeliano gli scienziati distinguono questo tipo di radiazione dalla radiazione ionizzante che invece determina la morte delle celule. A queste frequenze invece le conseguenze sembrano indicare che solo certe funzioni cellulari, tra cui la riproduzione, vengono soppresse, ma la cellula rimane intatta. 
Secondo Asher Yashalom, che dirige il gruppo Free Electron Laser dell'università, ha spiegato che finora una degli ostacoli da superare per queste ricerche era legato alla difficoltà nella produzione di queste onde, che hanno molte altre applicazioni nel campo delle telecomunicazioni, ma anche dell'imaging e dello scanning. Utilizzate per colpire le cellule del cancro polmonare, la radiofrequenza millimetrica sembra essere in grado di bloccare il proliferare delle stesse, ma ancora gli scienziati non hanno individuato la ragione. La cosa ancora più strana è che le cellule sane non reagiscono nello stesso e restano indisturbate. E' ancora presto per trasformare le scoperta in un metodo di cura, occorrono molte verifiche e poi resterebbe il problema di generare onde a queste frequenza. 

It’s long been known that radiation therapy is good news and bad news: It cannot discriminate between cancer cells and healthy surrounding cells. Lung tissue in particular is vulnerable to damage from x-rays. Could a different kind of radiation produce a better result for lung cancer patients?
That was the question asked by a group of Israeli researchers a few years ago. Recently they shared their surprising conclusions at the third International IEEE Conference on Microwaves, Communications, Antennas and Electronic Systems held in Tel-Aviv, and won funding from a European source to continue their studies. According to the researchers, a newly available type of radiation appears to disable cancer cells while leaving healthy cells unaffected.
“There are two kinds of radiation,” explains Prof. Asher Yahalom, one of the group from Ariel University Center. “Ionizing radiation is what is usually used for cancer. It has the ability to tear apart molecules, so it causes death to all cells. What we have done is quite different. We chose millimeter wave radiation, which is non-ionizing, so that it may only destroy functionality but not the cell itself.”
When tested in the lab on human lung-cancer cells, millimeter wave radiation rendered the cells unable to reproduce. “It disrupts their activity, although we don’t yet know how,” says Yahalom, who spent the summer and fall semesters as a visiting fellow at the Isaac Newton Institute for Mathematical Sciences in Cambridge, England. “We have also done irradiation of regular cells, and they were not affected. We are still gathering more data to be absolutely sure this effect is statistically significant and not due to any unrelated factors.”
New frontiers in radiation
In nature, Yahalom explains, there are electromagnetic (EM) fields everywhere. We are able to see light that is an EM field of very short wavelengths and high frequencies. We cannot see many other types of EM waves, such as the longer waves coming from cell phones and the microwaves that heat food. Millimeter waves are shorter than microwaves and longer than visible waves. “The problem with this type of radiation is that it’s hard to produce,” Yahalom says. “But in recent years there are more sophisticated components that produce wavelengths, and people have started to think about applications.”
Yahalom is head of Ariel’s Free Electron Laser (FEL) Laboratory User Center, part of the FEL lab headed by Prof. Avi Gover that developed a free-electron laser, using a magnetic structure known as “the wiggler”, that produces millimeter waves by accelerating electrons close to the speed of light and setting them on a wiggly trajectory. “The question was what would be an application for this laser, and we thought about applications in medicine, remote sensing, imaging and communications,”
says Yahalom.
Physics Prof. Konstantin Komoshvili is in charge of the experiments in conjunction with Prof. Jacob Levitan; engineering Prof. Boris Kapilevich, an expert in microwaves and millimeter waves; and biologist Stella Aronov of Ariel’s cancer research lab.
“Every major discovery must be checked and double-checked in a few laboratories,” says Yahalom, which is why the experiments are now being replicated in a Danish university. The two teams from Israel and Denmark recently got funding from the Eva and Henry Fraenkel Foundation in Denmark.
Yahalom stresses that research into using millimeter radiation against cancer cells is unique in the world.
“The radiation sources we are developing do not exist anywhere else in Israel,” he says. “In Russia and elsewhere, other groups are working on developing radiation sources but not on this application.”
Scientists in other countries are looking into terahertz radiation (shorter than millimeter waves) for devices that could detect hidden explosives, advance communications and imaging, or diagnose hidden skin cancer.
Tel Aviv University researchers in 2008 experimented with terahertz radiation to see its effects on healthy white blood cells. “We went the other way around -- we wanted to see how the radiation affects non-healthy cells, and this is quite novel,” concludes Yahalom.

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