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At least 37 records · Page 2Linked to original sources
PubMed1977

Particle radiation therapy: experimental basis and clinical application.

Conventional radiation therapy can eradicate cancers within tissues of their origin and regional spread with conservation of anatomic structure, thus preserving function and cosmesis. New treatment methods may improve the therapeutic ratio either by increasing the frequency of tumor control or lessening the treatment-related morbidity, or both. There are several physical and biological reasons why particle radiation therapy may increase tumor cell killing without increasing normal tissue sequelae. After preliminary basic research, clinical trials of fast neutron and proton teletherapy were started. Over 700 patients were treated with fast neutron beams in 3 U.S. research programs. These studies will be extended to include negative pi mesons and heavy particles.

Elementary Particles↗
PubMed1979

Sources of Atomic and Nuclear Data for Biomedical Purposes.

Users of nuclear and atomic data for biomedical purposes often have difficulty in identifying the most up-to-date and appropriate sources of such data. The biomedical Subcommittee of the UK Nuclear Data Committee have prepared a list of recommended data sources available at the beginning of 1978 on radioactive decay schemes; neutron cross-sections and data for neutron activation analysis; excitation functions for the production of radionuclides by charged particles; W-values for neutron and electron dosimetry; X- and gamma-ray cross-sections; stopping powers and ranges for charged particles; and dose deposition by electrons and beta particles.

Alpha Particles↗
PubMed1990

On the use of the pion stopping distribution and the lesion additivity concept for the calculation of effective doses in pion treatment planning.

The large spatial variation in LET, and hence in RBE, is one of the main obstacles in the development of routine treatment planning of charged particle beams. Since the biological effect distribution of plans cannot be realistically measured for each patient, a simple scheme of relating effect to basic empirical physical measurement is required. For the case of a pion beam, the high LET dose distribution is correlated with that of the pion stopping density, which can be indirectly measured using several techniques. A scheme based on this spatial correlation has been developed. In this method, after partitioning the local dose into a high and a low LET fraction, the local effective dose is computed using a simple formula extracted from a recent analysis of radiobiological results for mixtures of radiations of different LET. This simple formula can also be derived from a mechanistic model of mixed radiation action developed using the hypothesis of additivity of common intermediate lesions. In this paper, the concept of spatial correlation between the high LET dose and the pion stars is merged with the concept of lesion additivity for mixed radiation, from which a simple computational scheme is formulated for the calculation of effective doses in the treatment planning of pions. Similar schemes can also be developed for other charged particle beams.

Elementary Particles↗
PubMedDate not supplied

[A quantitative validation of the patterns determining the changes in higher nervous activity after irradiation with heavy charged particles under conditions of the influence of stress factors].

The major regularities that govern the alteration of the higher nervous activities after irradiation with heavy charged particles have been grounded quantitatively. The influence of the environmental factors on the exposed organism acquires a stress nature and is accompanied by the alteration of the central-central and central-peripheric relationships in major nervous processes whose pathogenesis is determined, to some extent, by a change in the homeostatic level of the synaptic energy transfer rate that depends quantitatively on the response of the irradiated organism at different stages of the development of radiation damage. The rate of the synaptic transfer at early periods of radiation damage development is 11.6, 9.7, and 12.4 (relative units) corresponding to the stages of radiation affection by heavy charged particles which permits to compare qualitatively and quantitatively the reactions of final acceptors of various executive morphofunctional structures after irradiation with heavy charged particles.

Animals↗
PubMed1978

[Patterns in the development of radiation tumors of the stomach and intestines].

In the experiments on dogs and rats it was shown that gastric and intestinal neoplasms arise under the influence of different kinds of radiation, these may be located in all portions of the stomach and bowel and are of a different histological origin. They are not infrequently primary multiple, mostly benign neoplasms which show multicentric growth. The frequency of tumors appearance, their localization, an average latent period, the degree of malignancy and multiplicity are conditioned by the amount of tissue dosage, the topography of their distribution in the alimentary tract and the level of total irradiation of the organism. With the increased dosage of local irradiation the latent period and multiplicity are decreased, while the incidence of malignancy raised. The optimum levels of the tissue dosage and the time of maximum tumor appearance were determined for each type of radiation.

Alpha Particles↗
PubMed1990

Radiobiology of pions in comparison with other heavy particles.

Our recent data on late effects of pions in spinal cord, lung and rectum in rodents is presented with reference to other high-LET radiations. Unlike high-LET radiations such as neutrons and neon ions, the RBE for late effects of pions (up to 1.5) is not found to be significantly different from acute effects. Because of the potential of matching treatment volume (especially by using dynamic treatments) to the target volume by using pions and heavy ions, it is of utmost importance to study the tolerance of normal tissues to late effects as a function of volume. Such knowledge combined with pion and heavy ion dynamic treatment could lead to a further step in heavy particle radiotherapy.

Animals↗