[Comparison of effectiveness of treatment for cervical carcinoma using different brachytherapy equipment]. / Sravnitel'naia otsenka éffektivnosti oblucheniia raka sheiki matki na razlichnykh brakhiterapevticheskikh apparatakh.

The immediate and end results of combined radiotherapy for cervical carcinoma stages I-III conducted at the N.N. Blokhin Center's Clinic (1982-1996) were compared. Intracavitary irradiation was carried out using the following radiation sources: 60Co-AGAT-V (208); 137Cs-Selectron (96) and 252Cf-ANET-V and ANET-VA (115). Remote-control irradiation procedure was identical in all groups. Five-year survival for stage I was 85.1% +/- 6.2; 85.7% +/- 13.1 and 87.8% +/- 1.2; stage II--67.5% +/- 4.0; 61% +/- 8.5 and 76.6 +/- 3.2; stage III--43.6% +/- 6.8; 57.7% +/- 9.6 and 70.9% +/- 5.4, respectively. Ten-year survival for stage I was 56.9% +/- 15.1; 85.4% +/- 13.1 and 80.1% +/- 1.5; stage II--65% +/- 5.2; 46.5% +/- 8.7 and 70.7% +/- 3.5; stage III--42% +/- 8.8; 51.3 +/- 9.9 and 64.6% +/- 6.2, respectively.

[Formalized method of deciding on treatment options in clinical oncology]. / Formalizatsiia vybora metoda lecheniia v klinicheskoi onkologii.

A method of constructing a "tree of problem solving" is suggested to work out viable and economical strategies of clinical therapy of tumors. The algorithm is illustrated by solving a hypothetical problem. A clinico-economic index is used to compare different modalities of tumor therapy, its lowest value representing the best regimen.

[Effect of dosage in the planning of intracavitary irradiation]. / Effekt moshchnosti dozy pri planirovanii vnutripolostnogo oblucheniia.

A comparison was carried out of different procedures of evaluation of the role of dosage in contact radiation effect. The assets and liabilities of the available methods of evaluation were studied with respect to the Ellis--time-dose-fractionation and linear-quadratic concepts. It was demonstrated that the sublethal damage repair model evolved by H.D.Thames and R.G. Dale (11, 16) in the framework of linear-quadratic approach to protracted irradiation can be used to compute iso-effective dosage when high or low loses are employed for fractionated intracavitary irradiation. A correction for dosage is a function of time of dose application and should be made for each fractionation regiment, i.e. number of fractions per week, dose per fraction, specifically in each case. The Thames-Dake model provides a means for establishing critical dosage for a modality of fractionated contact irradiation which is clinically significant, i.e. it differs from the set value by more than 5%. This, in turn, means that the absorbed dose should exceed the previously set one by at least 5%.

[The CT-stereotaxic neutron brachytherapy of brain tumors with californium sources on the ANET-B apparatus]. / KT-stereotaksicheskaia neitronnaia brakhiterapiia opukholei golovnogo mozga kalifornievymi istochnikami na apparate "ANET-B".

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.

[Computerized system of dosimetric planning of interstitial multiposition stereotaxic irradiation in neutron therapy of brain tumors]. / Kompiuternaia sistema dozimetricheskogo planirovaniia vnutritkanevogo mnogopozitsionnogo stereotaksicheskogo oblucheniia pri neitronnoi terapii opukholei golovnogo mozga.

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.

[Neutron therapy of endometrial cancer using californium-252 sources of high activity]. / Neitronnaia terapiia raka éndometriia istochnikami kaliforniia-252 vysokoi aktivnosti.

Endometrial cancer patients received intracavitary irradiation from the Anet-B installation using a high-energy 252-Cf source. Radical complex radiotherapy was given to 30 patients and radical-dose intracavitary irradiation--to 14 only. Incomplete palliative radiotherapy was carried out in 6 cases. Intracavitary radiation treatment preceded extirpation of the uterus and appendages in 10 cases. The complex radiotherapy proved effective in 93% of patients with stage I, II and III endometrial tumors.

[The ANET-B apparatus with 252Cf sources for intracavitary radiotherapy of cancer patients]. / Apparat ANET-B s istochnikami 252Cf dlia provedeniia vnutripolostnoi luchevoi terapii onkologicheskikh bol'nykh.

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. The above experiments made it possible to begin clinical testing of the unit. 46 uterine neck cancer, 65 uterine body cancer and 10 rectum cancer patients were treated from February 1983 to February 1987. The preliminary results of the clinical testing are positive.

[Concept of isoeffective doses in radiotherapy]. / Kontseptsiia izoéffektivnykh doz v luchevoi terapii.

The authors proposed the use of absorbed doses in standard regimens of irradiation to illustrate end-effects of unconventional variations of radiation therapy. They proposed that such doses should be defined as "biological isoeffective doses under standard conditions of radiation therapy" or, in short, "standard isoeffective doses". Three standard regimens of irradiation were described: separately for beta-beam, for continuous interstitial and fractional intracavitary radiotherapy. It was proposed that a standard isoeffective dose value should be expressed in "isogray" abbreviated as (i) Gy.

[Biological action of the radiation from high-activity 252Cf sources]. / Biologicheskoe deistvie izlucheniia istochnikov 252Cf vysokoi aktivnosti.

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). The comparison of radiation doses leading to a 90% decrease in initial cell viability provided the value of relative biological effectiveness (RBE) of 1.8 +/- 0.2 for mixed radiation and 2.2 +/- 0.2 for the neutron component at the dose of 10 Gy/h. AAF of mixed radiation was estimated as a ratio of radiation doses resulting in the above decrease of the cells viability, defined for the cells irradiation under anoxic or normoxic conditions. Simultaneously, AAF has been defined for gamma-radiation of 60Co. AAF has been shown to be 1.7 +/- 0.2 for 252Cf at dose rate of mixed radiation 10 Gy/h and 3.3 for 60Co. The index of "play back" is proposed as a more objective criterion of any modifier capability to overcome the radioprotective effect of hypoxia on tumour cells. The use of 252Cf sources of high activity instead of 60Co for intracavitary radiotherapy will increase the damage to hypoxic cells of malignant tumours.

[Topometric preparation of patients with cervix cancer for intracavitary irradiation on the ANET-B apparatus]. / Topometricheskaia podgotovka bol'nykh rakom sheiki matki k vnutripolostnomu oblucheniiu na apparate ANET-B.

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. The patients received a total of 138 investigations.

[Analysis of the reproducibility of conditions of intracavitary irradiation of patients with cervix cancer]. / Analiz vosproizvodimosti uslovii vnutripolostnogo oblucheniia bol'nykh rakom sheiki matki.

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.

[Dosimetric planning of intracavitary multi-position irradiation in cancer of the corpus uteri]. / Dozimetricheskoe planirovanie vnutripolostnogo mnogopozitsionnogo oblucheniia pri rake tela matki.

An algorithm for the dosimetric planning of intracavitary multiposition irradiation of corpus uteri cancer patients is proposed making use of some elements of the inverse problem solution and permitting one to calculate without computer. The algorithm is used for irradiation planning for the Soviet ANET-B unit with 252Cf sources. Conditions for the inverse problem solution applied to the dosimetric planning of intracavitary multiposition irradiation in case of the use of two dosing points have been formulated. The algorithm makes it possible to calculate a biologically isoeffective dose of mixed gamma-neutron 252Cf radiation.

[Radiation safety during work on the ANET-V therapeutic apparatus with 252Cf sources]. / Radiatsionnaia bezopasnost' pri rabote na terapevticheskom apparate "Anet-V" s istochnikami 252Cf.

The Soviet ANET-W intracavitary neutron therapy apparatus is charged with 252Cf sources, the total mass of the radionuclide being 2100 micrograms. The radiation exposure of the staff has been studied and the results presented. Possible emergency situations have been analysed, methods of their prevention and liquidation worked out. Induced radioactivity in the patient's body has been estimated. Radiation dose levels for the medical staff are 10-15 times lower for the ANET-W apparatus than those for 252Cf sources administered by the manual series system but 10 times higher than those for the AGAT-W gamma-apparatus. The design, blocking system and emergency reset of the sources provide for safe work on the ANET-W apparatus. During liquidation of an emergency situation irradiation of the staff does not exceed 0.3 of the annual maximum tolerance dose. The level of induced activity in the patient's body is insignificant as in 10.5 min it does not exceed background values.