[The CT-stereotaxic neutron brachytherapy of brain tumors with californium sources on the ANET-B apparatus].

A method for stereotaxic intratissue radiotherapy of brain tumors based on the findings of computed tomography is described. Radiosurgical implantation of sources with increased 252Cf content emitting mixed neutron + gamma-radiation was accomplished by means of an ANET-B apparatus by the afterloading method. Neutron irradiation is particularly effective in patients with malignant tumors possessing a large fraction of cells in a state of deep anoxia.

[Computerized system of dosimetric planning of interstitial multiposition stereotaxic irradiation in neutron therapy of brain tumors].

A computerized system PLUT-B intended for a dosimetric design of stereotaxic neutron brachytherapy of brain tumors, was developed. It is capable of simulating dose distribution in various parameters of irradiation, manipulating them, retaining the surgical aspects within the field of vision, and arriving at an acceptable dosimetric plan. The system permits visualization of a target with an applied dose field in the multiwindow mode, layer-by-layer vision in any direction, displaying a scheme of implantation, and drawing up of maps of isodose distributions.

[The ANET-B apparatus with 252Cf sources for intracavitary radiotherapy of cancer patients].

The authors give a brief description and the basic physico-technical characteristics of the AHET-B radiation therapeutic unit with 252Cf sources (the total radionuclide quantity is 2100 micrograms) for intracavitary radiation of malignant neoplasms of the uterine neck, uterine body and rectum. The results of the physical and technical testing and of the main dosimetric and maintenance study are given. Measures for the radiation safety of the unit users are described.

[Biological action of the radiation from high-activity 252Cf sources].

The radiobiological properties of mixed gamma-neutron radiation from 252Cf sources of high activity have been studied on chinese sand hamster cell culture. The source used has contained 1500 micrograms of radionuclide. In the study of radioprotective effect of hypoxia on the cells it is proposed to use anoxic attenuation factor (AAF) instead of the widely used oxygen enhancement ratio (OER).

[Analysis of the reproducibility of conditions of intracavitary irradiation of patients with cervix cancer].

The paper is concerned with the results of an analysis of reproducibility of conditions for intracavitary irradiation of 20 cervical cancer patients using metracolpostat, a combined therapeutic endostat consisting of 3 tubes: the central one to introduce radiation sources into the cervical canal and cavity of the uterus and 2 lateral ones with ovoids to deliver the sources to the vaults of the vagina. Topometric investigations for each patient were performed 4 times: before the first session of fractionated intracavitary irradiation with high activity 252Cf sources using the ANET-B unit and after each session of irradiation. It was shown that discordances between distances from the central endostat to the right and left lateral ovoids determined during roentgenotopometric preparation of each patient and taken as a basis of dosimetric design, and discordances between these distances determined as a result of roentgenotopometric control after each laying, are a random value distributed according to the normal law.

[Topometric preparation of patients with cervix cancer for intracavitary irradiation on the ANET-B apparatus].

The authors worked out methods of topometric investigation of cervical cancer patients during preparation for intracavitary irradiation using 252Cf fast neutron sources. The use of balloon catheters made it possible to determine a coefficient of projection enlargement in the point of interest, to determine accurately the distance between endostats, sources and contrasted organs of interest: the bladder and rectum. The results of the studies were used for individual design of intracavitary treatment as well as for the determination of radiation exposure of the pelvic organs in 38 patients.

[Morphology of cancer of the cervix uteri and surrounding tissues after preoperative intracavity therapy with high-energy 252Cf radiation sources and 60Co].

Comparative morphological study of uterine cervix carcinoma in 21 patients after a intracavity radiotherapy by 252Cf and in 18 patients treated with 60Co is performed. Total focal dose in a point A in both cases was 30 Gy. Morphometric study with the calculation of a volume correlation between stroma and tumour parenchyma in the two main groups and a control (untreated) group with a subsequent determination of a damage index has been done for the assessment of therapy.

[Experience in using echotomography in planning the irradiation of cervical cancer patients].

A possibility to use echotomography (ET) in the topometric preparation of patients with cervical cancer for radiation therapy is shown. In addition to ET computerized tomography (CT) was performed to 15 patients at the level of classic points A and B. Proceeding from the results of both studies topometric maps were prepared.

[Computer tomography in determining lung density for irradiation planning].

The paper is concerned with the problems of the determination of lung density in the irradiation planning for thoracic tumors using CT. The mean value of density that was equal to 0.252 +/- 0.

[Use of computed tomography for planning intracavitary radiotherapy of cervical cancer].

CT potentialities for irradiation planning have been demonstrated as a result of a study of 20 cervical cancer patients, Stages I-II, using a computerized tomograph for topometric preparation for intracavitary therapy with afterloading units, and subsequent gamma-beam therapy. Complete information on sections that are necessary for clinicodosimetric irradiation planning, has been obtained with the help of digital radiography, transversal tomography and mathematical reconstruction of secondary sections. The study was performed by inserting a centering mount and metrocolpostat after a preliminary determination of A point on the simulator.