[Results of irradiation using different radiation sources in the treatment of malignant parotid tumors]

Patients with malignant parotid tumors were treated at two different centres with slightly ionizing radiation (110 patients) and neutron therapy (15 patients). The treatment results are compared. The principles of comparison applied in this analysis are identical. The histologic classification was made according to the W.H.O. recommendation of 1972 and the staging according to Becske. Local tumor control is the criterion applied in the comparative assessment of both methods. The analysis has shown that there is no significant difference in the treatment results within the individual stages of tumor's advancement after application of an orthovolt therapy and a telecobalt therapy. Patients treated in early stages (stages I and III) had a substantially higher rate of local tumor control (72%) than patients in advanced stages (46%, stages III and IV). A more favorable treatment results was achieved by neutron therapy in all stages of tumor's advancement. In this case the rate of patients with local tumor control (87%) was significantly higher than after radiotherapy with slightly ionizing radiation (46%).

[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. The patients received a total of 138 investigations.

[The role of computerized tomography in the diagnosis and treatment planning of prostatic cancer]

The influence of computerized tomography on planning the therapy of 58 patients with histologically confirmed carcinoma of the prostate gland was examined. In classifying the early tumour stages there were differences from the clinical findings. With more advanced stages CT in some cases gave much more detail for diagnosing the extension. In 11.5% of the cases this led to the irradiation field being either enlarged or reduced. CT also proved to be useful for follow-up, especially as regards decisions on increasing the irradiation dose.

[Computed tomography in the diagnosis of ovarian, cervix and uterine cancer]

By means of computer assisted tomography (CAT) 22 patients with ovarian and 13 with uterus cancer were examined for diagnostic reasons. The results were compared with surgical findings. The advantage of CAT over objective clinical examination was shown particularly in cases where the tumour goes beyond the organ and lymphnodes are affected. In spite of the high information value of the CAT a differential diagnosis is difficult in cases of ovarian cancer. The method is little effective in case of corpus carcinoma in the stage I. In 14 patients with cervix cancer it could be shown, that CAT is inefficient for an early detection of malignant tumours of this localisation. By means of CAT, however, one can get additional information about the spreading of the process, particularly in cases with relatively high localized and not well detectable by bimanuel examination and information to clear up concomitant diseases of pelvic organs as well.

[Conventional roentgenologic methods and computerized tomography in the preirradiation planning for patients with esophageal cancer]

During the planning of irradiation of patients with esophageal cancer significant divergence is frequently noted between topometric maps obtained by conventional x-ray methods including axial tomography, and computerized tomography. Topometric maps based on these two methods were compared. Using a typical example of a series of 12 patients, divergences in expected dose loads on critical points were analysed on the basis of 3 variants of superposed topometric maps. Divergences in topometric maps result from errors in topometric methods and from an impossibility to reproduce precisely the level of a section and physiological conditions during repeated layings of a patient. Divergences in a focal dose (on the esophagus) can reach 8% in rotation radiotherapy, 20% in static irradiation, and on the vertebral canal 28 and 13% respectively. Factors that influence such divergences are discussed.

[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. Using the maps distances between points of interest were compared. It was shown that the mean value of the distance from the middle of the uterine cervix to the bladder posterior wall was 24 and 23 mm in ET and CT, respectively. Some methodological problems of ET for irradiation planning are discussed. It should be noted that ET provides ample information on the small pelvic anatomical structures that are of interest in gamma-beam and intracavitary radiation therapy of cervical cancer. ET positive features are its safety for a patient, insignificant costs and an opportunity to get information for a 3-dimensional irradiation planning.

[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 +/- 0.118 g/cm3 was obtained proceeding from a study of 118 CT sections of the lungs during quiet breathing. The respective value gets equal to 0.162 +/- 0.022 g/cm3 in deep breathing and 0.282 + 0.050 g/cm3 in full expiration. The values of lung density can vary in different persons. The range of measured values is equal to 0.119 = 0.441 g/cm3 in quiet breathing. The values of lung density vary within the limits of one section from the minimum value in its front part to the maximum one in the rear part. To determine lung densities that are representative for radiation therapy, CT should be performed with a patient breathing quietly in an uninterrupted manner. In significant deviations of density values from those accepted for isodose value calculation, individual consideration of lung density for each person is found appropriate.

[The Abris semi-automatic device for plotting the contours of the surface plane of the human body]

Semiautomatic contact contour plotter is designed to cope human body sections in supine position. Its operating principle and a design are presented. Experimental tests have shown that the error in contour plotting does not exceed 1--2 mm. It is useful in planning radiation therapy.

[2-dimensional ultrasonic scanning for irradiation planning]

The paper is concerned with the results of the utilization of echotomography in the topometric preparation of patients with malignant tumors for irradiation. Proceeding from the examination of 600 cancer patients in the All-Union Cancer Research Center. USSR AMS, it has been established that echotomography makes it possible not only to define the borders of pathology in the peritoneal cavity and retroperitoneal space but also to specify the relative position of the adjacent internal organs. Some practical aspects of the use of ultrasound for topometry are discussed. A possibility of using this method for the three-dimensional planning of irradiation is indicated. Using an echotomoscope one can obtain a contour of the section of a soft phantom with an accuracy of 5 +/- 1 mm that significantly exceeds the limits of precision of a contour measured with the help of a lead band where it equals 10 +/- 7 mm. Echotomography makes it possible to get a contour in any plane. In view of certain limitations of the echotomographic method one should also resort to x-ray methods for the topometric planning of irradiation to specify the position and size of the bearing osseous structures. While converting reduced ultrasound images in the scale of 1:1 the optic method with an episcope proved to be the most accurate one where an error of reproducibility of a contour reaches 1 mm. In the use of an optical-electronic device this value exceeds 10 mm and corresponds to 4 mm while utilizing a pantograph.

[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. An effect of the degree of the bladder filling on the organs located in a given section has been shown. It has been established that the degree of the bladder filling at the level of A and B points does not influence a distance from its posterior wall to the metrostat. It is assumed that intestinal radiation injuries can be prevented by controlling the degree of the bladder filling.

Variation in U.V. primary fluorescence-intensity of vital cells depending on 60Co gamma-radiation dose

Using impulse-cytofluorophotometry in the ultra-violet spectral region the author has shown on vital, unstained Ehrlich ascites tumour cells that the primary fluorescence intensity of this tumour is on day 11 after transplantation 20 per cent higher than on day 8. Storage of the vital cells for 25 min at 20 degrees C has no effect on this result. When the cells are exposed to 60Co to gamma-radiation on day 6, a new stable fluorescence level is established afted 20 hours. Measurements of the primary fluorescence intensity depending on dose have shown a significant rise starting from 75 rad at 48 hours after irradiation. The fluorescence intensity rises by 42.5 per cent of the control value at 3000 rad, but only by 31.5 per cent on exposure to 4000 rad.