Biomedical subjects
Publications and source records attributed to H Kuttig.
Radiotherapy for mammary carcinoma has special indications, depending upon the TNM stage and the localization. The use of megavoltage irradiation, a well-defined technique, and consideration of radiobiologic factors are necessary. Radiotherapy is the only therapeutic possibility in cases of recurrences.
In order to find out whether the moving field irradiation with rapid electrons and ultrahard X-rays of a 42 MeV betatron is suitable for the radiotherapy of the esophagus carcinoma, we took measurements on the Alderson phantom. By both methods--irradiation with rapid electrons as well as mono-axial pendulum irradiatin with ultra-hard X-rays--we did not achieve a satisfactory dose distribution, because lung segments of different sizes or the spinal marrow were reached by a relative dose which was too high. The bisegmental pendulum irradiation is the only one which leads to a dose distribution producing a good concentration in the target volume and sparing the surrounding tissues.
The conditions of dose distribution in telecentric small-angle pendulous electron irradiation of the thoracic region are reported on the basis of isodoses experimentally found using a phantom. Electron energies from 20 to 42 MeV were used, the axial depth amounted to 20 to 30 cm, the pendulous angles to 30 degrees, 40 degrees, or 60 degrees and the field breadth was 3 or 4 cm. Irradiations were performed monaxially as well as biaxially. The influences of single variables upon the dose distribution and especially on the radiation load to skin, lung and spinal cord are discussed.
A comparative examination of three Alderson phantoms by means of radiograms and computer tomograms shows that there are significant differences between the individual phantoms. Phantom I, for example, is inferior to phantom II because of the bad insertion of the bones into the surrounding plastic material (covered by air bubbles) and the inclusions of air in the soft parts. All phantoms have a rather strong osteoporosis of the skeleton which is most probably due to the production method [1,2]. Furthermore, the average absorption coefficients of the soft tissues show remarkable differences from one phantom to another.
The axial computed tomography of the skull has become an important part of the neuroradiologic diagnostics. The intracranial CT diagnosis is completed by the coronal sections which is used in particular in case of processes in the posterior cranial fossa and its differentiation of the supra- and infratentorial dimensions and in order to localize tumors in the sella region. The accurate determination of the tumor volume and the para-, supra-, and retrosellar dimensions makes possible an exact operation and irradiation planning. Solid, cystic and calcified tissues of the craniopharyngioma can be delimited. The quantitative evaluation by means of a computed tomogram of a tumor reduction obtained by surgery and irradiation with ultrahard X-rays (42 MV) with a target volume dose of about 5000 rd is illustrated by two examples. Under the above mentioned radiotherapeutic conditions, one partially resected craniopharyngioma with cystic, calcified and solid tissues showed a diminuation of the tumor volume of 60%, whereas the volume of a craniopharyngioma consisting of solid and calcified parts which had not been operated upon was reduced by about 40% two weeks after the end of the radiotherapy.
In a joint retrospective study by 17 radiotherapy clinics in German-speaking countries the results of treatment of bronchial carcinoma after radiotherapy were analysed in 7503 cases. The age peak was between the 60th and 70th year. Squamous-cell carcinoma was the most frequent histological type, followed by anaplastic carcinoma, with adenocarcinoma being rare. There was a high proportion of histologically not clearly identified cases (27% in central and 35% in peripheral carcinomas). Survival rate at one year was 31% for central (3662 patients) and peripheral (961 patients) tumours, but only 2% at five years. Prognostically there was no difference between histological types and kind of radiotherapy or technique, but total dose affected survival rate. At a total dose of less than 5000 rd the survival rate at five years was minimal. The prognosis of combined surgical and radiotherapeutic measures was slightly better than with a radiotherapy alone, but results were unpredictable for the individual case. It is concluded that radiotherapy aiming at cure should be used in imoperable bronchial carcinoma if the tumour state and general condition of the patient appear to make a cure possible. But if this is not the case, radiotherapy should be used only palliatively, i.e. only to ameliorate symptoms.
For all centers performing gynecological contact irradiation the use of afterloading techniques is urgently required, since they eliminate any radiation exposure to the personnel. The radio-therapist may position and control the empty applicators still free from radiation withoug haste. This procedure diminishes the occurrence of overdosages and underdosages. The care for the patients is possible without radiation exposure, and the morbidity of contact therapy can be reduced by occasional mobilization of the patient, the applicator without sources remaining at its place. The fully automatic apparatus "Curietron" using cesium-137 sources (0.662 MeV gamma emission, half-life period 26.6 years) with an equivalent source activity (factor 2.6) yields the dose distribution demanded in the gynecologic field which in practice is identical to that of Ra-226 (medium gamma emission 1 MeV, half-life period 1620 years). With similar dose distribution, a biological and therapeutical effect alike to Ra-226 may be expected from Cs-137. In comparison with Ra-226, the following advantages of Cs-137 may be mentioned: Lower half-value thickness of 5.5 mm lead (low expenses for radioprotection), less danger with handling (no emanation of radioactive gases), and lower contamination risks in case of breaking. The measured dose distributions at equivalent source activity and similar geometry of the applicators revealed the possibility with regard of all techniques of gynecologic irradiation utilized in our field of arriving at similar relative and absolute dose distributions by means of the Cs-137 afterloading technique. Whilst short-term afterloading irradiation with highly active sources, their radiobiological effectiveness being not yet ascertained, has to be tested at appropriate scientific centers, it is necessary to demand afterloading techniques with dosages and duration of irradiations approved over decades for all centers of gynecological contact therapy because of radiation protection.
Between 1960 and 1975, 53 mammary carcinomas have been observed in a collective of 15000 women a part of whom, comprising finally 80 per cent, was free from troubles (annual prophylactic examination for breast cancer). Of these 53 cases were available two up to eleven preceding mammographic series made within an observation period of 0.2 to eleven years. A "mean growth curve" was obtained empirically, based on 163 mammographic tumor measurements with tumor sizes between 2 mm and 60 mm. In the course of a development period between two and eleven years, 33 per cent of the carcinomas were seen to accelerate their further growth in comparison with the initial value; 66 per cent revealed an increasing slow-down of growth, and all tumors showed considerable changes in their growth rates. Mammary carcinomas altogether continually decelerated their growth as measured by the duplication time of the tumor volume from Tv = 309 days on the average up to an average of Tv = 381 days after two through eleven years. The mean growth curve exhibited an exponential shape which was completed by biomathematical methods and can be described by means of a Power function. It corresponds well to the rate of incidence of the mammary carcinoma which shows an identical rise in relation to increased old age. The medium growth time from a primary cancerous cell with ten micron in size up to the tumor 2 mm in diameter may be estimated biomathematically only and amounts to ten or twenty years with 23 duplication periods. The further average growth rate between the tumor sizes of two and ten millimeter, stages which can be diagnosed roentgenologically, was empirically six years; the most quickly growing tumor needed almost two years. For the purpose of early cancer detection (tumor size below 10 mm, lymph nodes histologically free from metastases), the serial mammography to be performed every 18 months or two years is the only technique which provides utilizable early recognition marks and besides does allow a simple judgement. Solely the symptoms "suspect desification, partly spiculated" in sixty per cent and "typical cancerous microcalcification" in forty per cent have been observed as the earliest signs. The reliability ("certainty") of mammography is frequently overestimated (false negative rate: 7 to 18%) and should be quoted only for collectives where control mammographies have been made over a period of five or ten years. Roentgenological controls of alterations below three millimeter in size and without an indication for biopsy ought to be performed within six months, and still sooner in case of larger alterations. It is not possible earlier than after five or ten years to judge of the radicality of a therapy, as spread cancerous cells, on he average, reveal similar growth rates as does the primary tumor.
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From 1958 to 1970, in 435 cases (60%) out of 725 carcinomas of the uterus sole radiation therapy by cobalt-60 beads was performed; in 288 cases (39.7%) surgery was done (combined with tele-cobalt-irradiation in almost all cases, 5000 to 6000 rd TD). Two cases (0.3%) received no treatment. The unfavorable selection of the irradiated women (average age 64,6 years) as against the surgically treated ones (average age 50.9 years) did allow a complete intracavitary irradiation only in 60.6% of the cases; in 39.4%, the dose had to be reduced considerably. The five-year survival amounted to: 64.4% after sole irradiation, 93.2% after operation/postirradiation in stage I; 46.9% after sole irradiation, 75.0% after operation/postirradiation in stage II; 30.8% after sole irradiation in stage III. No survivors existed in stage IV. Mortality from treatment with sole irradiation amounted to 1.8% (8/435). Radiation fistulas were observed after sole irradiation in 0.4% (1/435), after operation/postirradiation in 0.7% (2/288). As long as there is no satisfactory afterloading technique for intracavitary irradiation of the carcinoma of the uterus, an application of cobalt-60 beads seems to offer the following advantages as compared to an implant of radium filters: Shorter duration of the application, better adaptability to the cavitary lumen, diminished risk of perforation. No perforation was observed.
From 1960 to 1972, 276 out of 330 cases of ovarian cancer were treated by different techniques of postoperative radiation therapy; 54 advanced cases underwent prospective chemotherapy. Radiogold intraabdominally administered (190 to 300 mCi), telecobalt (5000 rd) or the combination of radiogold and telecobalt was chosen for postoperative radiation therapy. Cyclophosphamide (Endoxan), prednisolone, and gestagenes (Prothil) were given as a long-term chemotherapy. The most successful technique of radiation therapy is confronted with long-term chemotherapy after three years (five years) of survival: Stage I a, b, c: Radiogold = 91.7% (66.7%), chemotherapy (only I c) = 100%. Stage II a, b: Radiogold + telecobalt = 47% (35%), chemotherapy = 85%. Stage III: Radiogold + telecobalt = 25% (0%), chemotherapy = 52%. Stage IV: Radiotherapy = 0%, chemotherapy = 25%. The absolute five-year survival without chemotherapy amounted to 23%. The mortality curve under chemotherapy shows a four-year survival rate of 88%, if tumor cells had been detected microscopically (ascites, omentum), but of only 30% after macroscopical verification of the tumor. Therefore, the maximally possible partial resection of the tumor is recommended in inoperable stages before the beginning of chemotherapy. "Prophylactic" long-term chemotherapy following macroscopically complete surgical treatment is recommended, whenever microscopical spread of tumor cells appears to be possible. In inoperable stages, chemotherapy ought to be applied prior to radiation therapy. In stages I a, b, c, and II a, postoperative irradiation with radiogold (100 mCi) and in stage II b additionally radiation teletherapy of the pelvis (6000 rd) is recommended.
Based on dose measurements at the phantom, the dose distributions obtained during electron therapy by the use of wedge filters made of polystyrol are reported. Energy doses from 15 to 42 MeV were applied; angles of wedges amounted to 10 degrees, 30 degrees, 45 degrees, and 60 degrees. Only by wedge-angles larger than 45 degrees, it was possible to bring about significant changes in the dose distribution. The results obtained are presented diagrammatically. The influence exerted by the wedge-angle and by electron energy upon the inclination of the 50%-isodose to the axis of the useful beam is shown by tables.
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