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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. Dosimetric planning was conducted by means of an original computer system. Devices and radiation-technical equipment for adaptation of the ANET-B apparatus for irradiation of neurosurgical patients are described. The indications for the use of this method and its place among the complex of measures for the treatment of patients with new growths of the brain are discussed. The first experience in using CT-stereotaxic neutron brachytherapy with californium sources on the ANET-B apparatus for the treatment of 6 patients with malignant glial tumors of the brain is dwelt on.

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. It is intended to be used by a physician, convenient in operation, the time at the design stage is 35-40 minutes.

The paper is concerned with main values of dose exposure of the USSR population as a result of medical roentgenological investigations. The authors issue practical organizational-methodological recommendations for irradiation reduction resulting from giving up chest x-ray, a decrease in prophylactic fluorography, improvement of technical facilities for investigations of the digestive tract, and organization of roentgenoradiological departments as independent health service units.

The authors presented clinical material on cerebral hemodynamics in patients with neurological pathology in suspected tumor vascular cerebral diseases and craniocerebral traumas. Investigation of cerebral microcirculation was performed using a multidetector single-photon emission tomograph "Testoscan" (USSR) after iv administration of 99mTc-hexamethylpropilene-amyloxine. This radiopharmaceutical is good for the evaluation of cerebral perfusion and gives a clinician rich information on cerebral microcirculation.

The paper is concerned with the results of single-photon emission tomography and gamma-topography in patients with cerebral tumors, cerebral circulatory disorders and pathology of the liquor system. Tomographic investigation was shown to enhance the accuracy and reliability of the detection of cerebral tumors. Single-photon emission computerized gamma-tomography (SPECT) permitted the detection of structural and morphological cerebral changes in disturbed cerebral circulation of various etiology. SPECT together with computerized tomography and radionuclide cisternography was shown to be an auxiliary method for visualization of the cerebral cisterns. Radionuclide tomographic images as compared to gamma-topographic findings of the brain possessed a high statistical significance and good resolution.

The results of radiation therapy conducted after various schemes were compared in 77 patients operated on for medulloblastoma of the posterior cranial fossa: 1. irradiation of the posterior cranial fossa area; 2. irradiation of this area and the entire length of the spinal marrow; 3. total irradiation of the CNS. Stages in a metastatic process necessitate irradiation in stages, i.e. irradiation of the posterior cranial fossa and the length of the spinal marrow followed by irradiation of the cerebral hemispheres one year after the operation. Total irradiation of the CNS shortly after the operation is recommended only in the presence of early metastases.

A TESTASCAN single-photon emission multidetector gamma tomograph is a special purpose unit designed to investigate RP distribution in the brain. It permits obtaining transversal tomographic images with the resolution of about 10 mm, the thickness of an emitted layer being about 15 mm. The time of patient's examination during obtaining an image of 10-12 layers does not exceed 30 min. and can be reduced by increasing RP activity and minimizing the number of emitted transversal sections. The clinical testing of the unit has shown that it is reliable in maintenance and simple to operate during radionuclide data collection, reproduction and analysis. Emission computerized tomography in brain tumors can be regarded as a method increasing the accuracy and reliability of radionuclide diagnostic examination of neurosurgical and neurological patients.

A model of normal tissue injury as a result of exposure to ionizing radiation is based on an assumption that the degree of tissue injury is determined by the degree of destruction by certain critical cells. The dependence of the number of lethal injuries on a single dose is expressed by a trinomial - linear and quadratic parts and a constant, obtained as a result of the processing of experimental data. Quantitative correlations have been obtained for the skin and brain. They have been tested using clinical and experimental material. The results of the testing point out to the absence of time dependence on a single up to 6-week irradiation courses. Correlation with an irradiation field has been obtained for the skin. A conclusion has been made as to, first, time lag blurring time dependence within a certain range of courses, second, the presence of a component of true regeneration of which the degree depends on the volume irradiated. Proceeding from such an understanding of injury-regeneration processes a conclusion has been made that the concept of isoefficacy of irradiation courses is conditional. Volume-time fractionation is a promising direction in the development of radiation therapy.

A gamma-topographic study of the orbit was performed in 64 patients with unilateral exophthalmus using 99m Tc-pertechnetate. Some peculiarities in the RP distribution in the focus of lesion in malignant and benign neoplasms and inflammatory processes in the orbit were revealed. Correlation between RP accumulation intensity in the focus and the degree of RP vascularization and volume was shown. The method does not allow assessment of the morphological nature of a process however its use extends the diagnostic potentialities in specifying the genesis of unilateral exophthalmus and facilitates the choice of appropriate therapy.

The authors present the results of proton therapy in 59 patients with different hypophyseal adenomas. The period of observation lasted from 6 mos. to 5 yrs. Irradiation was done using a multifield-convergent method and a proton beam of the ITEF synchrotron. The beam energy was 200 MeV, the beam diameter 7-15mm. Radiation response and immediate results were evaluated for all the patients. The least favorable results were noted in the patients with prolactinomas, for which, in addition to irradiation, parlodel therapy is needed. No marked radiation reactions, neurological complications and manifestations of hypopituitarism were observed with the chosen doses and schemes of irradiation.

Seven patients operated on for intracerebral tumors received a course of large fractionating irradiation during which the patients' clinical status, changes of the ventricular CSF pressure, intracerebral pressure of the interstitial liquid, biochemical parameters of the blood and CSF and the EEG summary rate were assessed over time. The patients' reaction was characterized by a moderately expressed change of the above parameters in response to irradiation which returned to normal within 12 hrs. following large fractionating irradiation.

Eight patients underwent simultaneous polarographic studies of pO2 in the brain normal tissue and glial tumors under the conditions of inhaling 100% oxygen and a hypoxic gaseous mixture (10% of oxygen and 90% of nitrogen). It has been established that the inhalation of 100% oxygen causes an increase in pO2 in the brain normal tissue and tumor by 100-115%. A short-term moderate gaseous hypoxia leads to a decrease in pO2 both in the brain normal tissue and tumor by 30% on an average.

The pathogenesis of late radiation necroses remains still unsolved in the problem of cerebral radiation injuries. The problem of primary site: vessels or medulla is a disputable one. In this case cerebral radiation nectosis developed in a 32-year-old woman 1.5 yrs. after the last course of radiotherapy for hypophyseal adenoma was over. The authors give an irradiation scheme and a detailed histological description of the foci of late radiation necrosis in the temporal lobe and in the substance of the Varolii pons which is not the zone of direct exposure. The histological picture described in the above foci is similar in many details to the process that takes place in experimental allergic encephalomyelites developing in sensitized animals. The time course of histological changes in the foci of radiation necroses shows that the process does not develop steeply but increases gradually affecting the adjoining zones of the medulla that cannot be accounted for by the direct involvement of the medullary tissue only during radiation. Thus it can be assumed that the process develops like an allergic reaction where the role of the allergen is played by the decomposition products of myelin that appear in the affected focus.

The use of proton beam irradiation in neurosurgical clinical practice helps to find a solution to the problem of the treatment of inoperable malformations employing this method in some cases as an alternative to surgical intervention. Hypophyseal tumors, tumors of the cavernous sinus, arteriosinusal anastomoses in the cavernous sinus area, and arteriovenous malformations are irradiated at the N. N. Burdenko Institute of Neurosurgery, USSR, AMS using the medical proton beam of the Institute of Theoretical and Experimental Physics. Methods of "piercing" irradiation and methods with the use of Bragg's peak are being developed. At present over 200 patients with hormonally active hypophyseal tumors, 30 patients with tumors of the cavernous sinus, 23 patients with deep seated arteriovenous malformations, and 10 patients with spontaneous arteriosinusal anastomoses in the cavernous sinus area have been irradiated. This method seems to hold promise in neurosurgical practice. Extension of the range of clinical applications of proton beam therapy in neurosurgery requires the development of various techniques of irradiation, all possible approaches to various targets on the basis of contemporary methods of computerized diagnosis, topometry and irradiation design.

The paper is devoted to an analysis of the present-day role of radiotherapy of pituitary adenomas with relation to tumor spreading and the patient's neuroendocrine status. The authors made use of data obtained from the N. N. Burdenko Research Institute of Neurosurgery, USSR Academy of Medical Sciences. They analyzed the results of gamma-beam therapy, proton-beam therapy and radiosurgical implantation of 90Y granules used alone as well as in combination with surgical intervention. Based on the analysis of the clinical data on 320 patients, a conclusion is made on the indications for one or another method depending on the stage and course of the disease.

Using the findings of ventriculo- and cisternography with 99mDTPA performed in 30 patients, it has been shown that the signs of open hydrocephalus should be considered the following: the visualization of the lateral ventricles, the third and fourth ventricles, the great cistern and the subdural space of the cervical part of the spinal cord (in preset time intervals); RPH complete absence (even after 24 h) in the subdural space of the brain (convencital, medial and parasagittal parts). Significant radiological signs of occlusive hydrocephalus are obtained from the visualization of one or two lateral ventricles; the visualization of the third ventricle and the great cistern. CSF disturbances revealed in radionuclide ventriculography can be used for the assessment of CSF resorption as well as the stage of process (decompensated stage).

An analysis of the radiological signs is presented proceeding from the results of examination of the visualization of the CSF tract in 123 patients in whom radionuclide cisternography with 99mTc-DTPA was performed 1,3,6 and 24 h after administration of a radiopharmaceutical. The radiological appearance of pathology of the CSF system in a long-term period after penetrating craniocerebral wound was developed.

Gamma topography of the brain as a differential diagnostic method permits the recognition of an inflammatory process and specification of its localization. It can be widely used in an outpatient setting (both for children and adults). Altogether 61 patients were investigated: abscesses of the brain (36 patients, of them 16 children); focal arachnoencephalitis (14 patients, of them 5 children); arachnoiditis (11 patients). Gamma topography of the brain makes it possible to clarify early topical diagnosis of a process. Due to its simplicity, small radiation exposure and noninvasive character of the method can be recommended in outpatient clinics and hospitals both for children and adults.

A study was made of the cerebral hemodynamics by assessing the distribution in single-photon emission computerized tomography with 99mTc-hexamethyl-propyleneminoxyne in health using a Testascan in 9 standard slices. The whole set of tomographic slices was conventionally divided into 3 levels. For better orientation in gamma-tomographic images, pictures were presented where in addition to scintigrams a morphological scheme of the cerebral parts with the marked parts perfused by cerebral arteries, was given.

The character of blood supply to the affected cerebral hemisphere was studied on the basis of angiography performed before and after occlusion of the afferent vessels of large arteriovenous aneurysms in 90 patients and study of cerebral circulation on a gamma chamber in 30 patients. It was established that the affected cerebral hemisphere is supplied with blood from the vascular basin of the same side. The importance of the regional blood flow is determined by the localization and the sources of blood supply to the aneurysm. Before the operation, the maximum decrease of regional blood flow was found in zones with contiguous blood supply, namely in the parietal and parieto-temporal areas. The occlusion of afferent vessels of the aneurysm leads to an increase in the flow of blood aneurysm is supplied with blood from the cortical arterio-arterial anastomoses in the zones of contiguous blood supply.

Radionuclide cisternography (RCG) was performed in 78 children with different forms of hydrocephalus: external, internal (ventricular) and obstructive. Radiological signs were determined by spatial-time distribution of a radiopharmaceutical over the liquor pathways. Morphological and liquorodynamic disorders (liquor circulation and resorption disorders) served as a basis for the differentiation of hydrocephalus forms.

The article reviews various methods for the exposure of pituitary adenomas to the effect of radiation applied either as the only measure or in combination with surgery and drug therapy. The indications for radiotherapy are discussed according to the size and hormonal activity of the tumor.

Gamma-topography of the cerebrospinal fluid tracts of the spinal cord (GCTSC) was conducted in 28 patients with traumatic injuries of the brachial plexus at the preganglionic level. The object of GCTSC was to identify the character of damage inflicted to the spinal cord, its meninges, and the roots at the preganglionic level in the presence of the pain syndrome. Spatial-temporal distribution of the radiopharm agent in the submeningeal space served as the basis for setting apart radiological signs characterizing the anatomical disorders and disturbances in cerebrospinal fluid dynamics in the submeningeal space of the spinal cord. The radiological picture was always composed of adhesive-cicatricial and adhesive-cystic processes with arachnoid cysts or cerebrospinal fistulas in the cervicothoracic segment of the spinal cord.