PROTON BEAM INSTEAD OF A SCALPEL

by Marina KHALIZEVA, journalist

The engineers of the Physicotechnical Center (Protvino, Moscow Region) of the RAS Lebedev Physics Institute (FIAN), headed by Vladimir Balakin, RAS Corresponding Member, developed a brand new plant for irradiation of malignant tumors by protons. Notable for high efficiency this plant is tens of times more compact and economical as compared with the existing ones. Today the plant is used for experiments on laboratory animals, which will be completed in the short run, and clinical trials will start in late 2011-early 2012.

This is not the first checking of productivity and accuracy of the most intriguing project by a group of Moscow scientists. The proton-therapeutic center equipped with the Balakin plant operates at the Protvino municipal hospital since 2007. From that time physicists are carrying out experiments there in a close cooperation with biologists and physicians. The main point of experiments is artificial development of malignant tumors in a mouse hind leg with consequent proton therapy sessions. As a result, all the experimental animals were completely cured. It is worthy of note that the male mice preserved their potency after treatment and soon produced normal progeny. Meanwhile, according to Yelena Smirnova, a senior researcher of the Institute of Experimental Biophysics (Pushchino, Moscow Region) and a participant of the experiments, it is just a reproductive system, which is most sensitive to irradiation, but the proton beam energy does not destroy it. The scientists were amazed also by high pinpointing of the tumor by the beam as a distance between the mouse leg and its genitals did not exceed several millimeters but the beam hit home. At the final stage of a biological experiment, the mice will be placed in dummies to simulate the location of a tumor in a man and check the efficiency of proton radiation.

It should be pointed out that radiation therapy has long been recognized by the world medical community as an effective method of cancer control. It was first used in 1896 by Emil Grabb, an American physician from Chicago (Illinois), who irradiated a 55-year-old woman with breast cancer. It took place just several months after the German physicist Wilhelm Roentgen (1845-1923) discovered X-rays, which were named later after the inventor. From then on, other types of ionizing radiation were also used such as gamma, beta and neutron emission produced by electron accelerators. The latter are widely used in treatment of a majority of tumors and are "the most industrial method" according to Balakin, who spoke at the project presentation at the press center of the Izvestiya newspaper in Moscow on March 30, 2011. However, the efficiency of their usage in radiation therapy does not exceed 50 percent.

Proton irradiation is a different matter. As the scientist puts it, these particles are dispersed to a lesser degree in the organism and release practically the whole energy at the end of the range. Its length depends on a speed obtained in the accelerator. If the speed is adjusted to tumor localization, one can carry out purposeful destruction of malignant tumors with a minimal effect on health. The proton therapy has been practised already for 50 years in about 10 medical centers in the world including Russian centers in Dubna, Moscow and St. Petersburg, which have the corresponding plants at their disposal. For the last decades a total of approximately 70,000 patients underwent accelerated beam treatment. However, despite the optimistic figures (up to 90 percent recovered from cancer), this method remains cost consuming till now due to the high cost and bulk of the equipment. The inventor says: "Medical proton accelerators are, in fact, monsters, which occupy many-storied buildings, need their own electric power plants, high-power refrigerators and other facilities. But we suggested a complex, which surpasses by far the world analogues in their engineering and operating characteristics."

Here some departure from the subject needs to be made. The advanced treatment method of cancerous diseases attracted Balakin's attention already in the 1970s, when he worked together with Academician Gersh Budker (1918-1977) at the Institute of Nuclear Physics, RAS Siberian Branch. In the middle of the 1990s Balakin moved to Protvino to head the Physicotechnical Center, a special division of FIAN. From his teacher Balakin inherited a thorough and keen understanding of the subject, bold and original thinking, and singular scientific insight. Academician Gennady Mesyats, RAS Vice-President and FIAN Director pointed out: "Were Budker had been alive today, he would support Balakin even now. Volodya is a person of natural gifts with an extensive background knowledge and a distinct type of mind oriented to invention." These qualities helped him develop a proton-therapeutic plant of a new generation. In 2008 his project received an award "Prizewinner of the Year" in the nomination "Best Research and Development Project" by the Moscow Region government. The making of the complex itself was included into a program of economic and social development of Protvino.

What is a special feature of the Balakin accelerator? Its compactness as the whole equipment can be fitted in a 50x50 m room. Minimal costs of electricity consumption as these instruments need several times less electric power for production of protons. As regards the intellectual framework, all processes are maximally computerized here, and therefore the whole equipment can be serviced by one staff member per shift! Besides, it is its low price, which is 10-15 times less than its foreign counterparts. All the aforesaid are, of course, important but insufficient conditions for saving of hundreds of thousands of human lives.

The innovative irradiation method, developed in cooperation with the Medical Radiological Research Center, RAMS, in Obninsk, Moscow Region, and expansion of opportunities of proton radiation as compared with the traditional methods, is the main "trump card" of Balakin and his colleagues. As he puts it, the effectiveness of cancerous diseases control under radiation therapy rises greatly, if a cumulative dose is increased in tumor. Electron accelerators do not make it possible to increase it as a healthy tissue will suffer in this case. However, the bulky radiators now in use also fail to solve the problem as the so-called collimators, or beam focusing devices, extreme-

ly heavy by weight, are used in them. They are made individually for each patient with account of the location and shape of a proliferous tissue. A patient is put to bed in such a way that his cancerous growth is positioned exactly opposite an inlet of this device (sometimes it takes up to 20 min), and only after that a wide beam of particles is released, of which only a part falls on the pathological formation. Balakin says: "It is obvious that many collimators cannot be made for each patient, only one or two, and therefore tumor is exposed to radiation only from these two directions. A single dose cannot be increased, otherwise the adjacent healthy tissues will suffer inevitably. Thus, a treatment period has to be extended for a month or more."

The Protvino accelerator provides irradiation from 36 directions. Moreover, the algorithm of their penetration is worked out so that only malignant cells receive a lethal dose, and those unaffected by oncogenesis continue their biocycle. It results in a reduced time at hospital and increased effectiveness of his treatment, as the tumor has no time to regenerate. By the way, the operating principles of a proton accelerator are know-how of the inventors and are protected by 31 international patents.

According to Balakin, the plant can serve up to a thousand of patients per year at the early stage, and subsequently, as new methods are mastered, its productivity can increase to 2,000.

But development of the project in full measure seems impossible as yet. At present, in Dimitrovgrad (Ulyanovsk Region) a high-technology medical center is under construction (the total amount of financing is 13.9 bln rubles) for 4 proton accelerators, three--general purpose and one--for eye tumor treatment. However, according to Vladimir Uyba, Director of the Federal Biomedical Agency, these accelerators will be purchased abroad. There is shortage of funds for promotion of national technologies in this field, though the Rosatom state-owned corporation is planning to cope with this problem. Gennady Mesyats noted in his interview to the Rossiiskaya Gazeta newspaper in 2010: "We talk a lot about modernization, but at the same time we do not notice or do not want to notice what we already have. We ask the higher state bodies for help and support but find no response. Indeed, no man is prophet in his own country. In the meantime, two of Balakin's plants have already been installed abroad. One is in the USA, in the very center of high-tech, namely, at the Massachusetts Technological Institute (it operates in a demonstration mode as yet but is available for scientists and practical physicians, studying its characteristics and purchase conditions), and the other is in Slovakia (Ruzomberok)."

China also showed interest in compact plants. Its businessmen promptly appraised efficiency of our accelerator, its low cost as compared with other prototypes, and a high capacity. Therefore, they intend to purchase several plants at once and install them not in large medical centers but in ordinary hospitals.

There are only two such complexes operating in Russia. Apart from the Protvino hospital, another one was installed at a hospital of the RAS Research Center in Pushchino in 2010. However, the latter lacks a sufficient number of scientists and physicians of an oncological profile as yet. Therefore, Protvino still remains in the focus of scientific research in proton radiation therapy. The research supervisor is Academician Anatoly Tsyb*, who headed the Medical Radiological Research Center in Obninsk more than 30 years and possesses wide experience in dealing with ionizing radiation. The highly skilled specialists of this center, who closely cooperate with physicists, medical men and biologists, express confidence in successful completion of experiments on laboratory animals. The first patients for a mobile plant are expected not earlier than the next year. Despite obviousness of the treatment effect by proton energy, we mean only clinical trials.

* See: A. Konoplyannikov, M. Kaplan. A. Tsyb. "Realitiesand Perspectives of Cell Therapy", Science in Russia, No. 2. 2008.--Ed.