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Purpose: Presentation of the history, status and prospects for the development of proton therapy. Material and methods: The history of proton therapy (PT) is divided into two periods. The first one – the experimental period lasted since 1954 to 1990, when proton therapy was carried out at the ten facilities in physical institutes. The research accelerators and the horizontal proton beams with a fixed direction are used. The second period is from 1990, when the first clinical proton center was commissioned in a multi-field hospital in the city of Loma Linda, USA. In the first period, the necessary technical tools were developed and the advantages of using accelerated protons in remote radiation therapy formulated by R. Wilson in 1946 were confirmed on a limited (about 9,000) patient population: halving the radiation load on the healthy tissues surrounding the tumor and on the organism as a whole compared to γ- and electron irradiation and high dose gradients at the borders of the dose distributions and the tumors. This allows to increase the dose in the tumor (target), increase the probability of the tumor resorption and at last to irradiate tumors, including small sizes, located near critical organs and structures. By 1990, in three experimental centers in Russia (JINR, ITEP, PNPI) accumulated about 30 % of world clinical experience. Today, more than 70 multi-cabin and several single-cabin clinical based proton therapy centers operate in the world. Almost all centers are equipped with gantry installations for PT for 95 % of patients. Today proton therapy is indicated and is used for the treatment of 10–15 % of all malignancies of cancer incidence structure. Results: Healthcare in Russia needs 10–15 multi-cabin proton (and ion) centers. Currently, there are one experimental PT center in the JINR, where up to 100 patients are exposed pea year. The modern proton center was commissioned at the Medical Institute Sergei Berezin in St. Petersburg with two gantry of company Varian. The IBA proton center in Dimitrovgrad is expected. The single-cabin proton complex of domestic production has been operating in Obninsk since 2017. 20th-century technologies and the horizontal beam (without the possibility of its rotation) are used in this complex for treatment of patients with small head and neck tumors. Conclusion: Equipping the Russian health care facilities with proton therapy facilities is inevitable. Russia will buy them worldwide for decades, like almost all types of high-tech medical equipment, are bought today, or can produce them locally. All the prerequisites needed for production (rich physical – technical experience, scientific and industrial potential) are available.

An analysis is made of the possibility of using intensity interferometry in obtaining images of spatially noncoherent polychromatic sources. It is shown that in the case of spectrally pure processes the propagation operator of the spatial part of the correlation function has a transformation kernel which is the temporal coherence function. Consequently, optical reconstruction with the aid of the Fourier transformation results in distortions of the image whose magnitude depends on the relative frequency bandwidth of the radiation emitted by the object. If a point reference source is used, distortions depend also on the spectral characteristics and spatial position of this source.

A theoretical analysis is made of the propagation of a space-time correlation function in a homogeneous nondispersive medium. The solution of a six-dimensional wave equation, describing the propagation of the coherence function, is found by the angular spectrum method. The relationships obtained make it possible to analyze fully the influence of the spectral composition of radiation on the spatial coherence. For example, in the case of a spatially noncoherent source there is a critical distance zcr, such that when z zcr, the polychromaticity of the field makes a negligible contribution to the spatial coherence; however, if z zcr, the linear behavior of the coherence radius, Rc z, typical of the van Cittert-Zernike theorem, gives way to the dependence Rc z. Similar conclusions apply also to a spatially coherent source.