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Background: Radiotherapy plays a pivotal role in tumor treatment. Brachytherapy as an additional radiation technique allows local dose increments in areas at high risk of local failure., Patients and Methods: Our past 15-year experience with tissue-equivalent bendy applicator brachytherapy at the University Hospital Münster, Germany was reviewed. A series of 74 consecutive patients who had mainly been treated for sarcomas with perioperative brachytherapy was analyzed with a focus on local relapse-free survival and side-effects., Results: The 5-year local control rate was 73% in primary treatment situations with a significant influence of additional external irradiation, surgical margin depth and tumor entity. Late sequelae of combined modality treatment were observed in 40 patients (54%) and mainly concerned wound healing (n = 18, 24%)., Conclusion: A high-risk collective, in view of local failure, showed adequate local control rates as well as acceptable late sequelae. Flab brachytherapy is a good treatment option to achieve local radiation dose increments in patients at high risk of local failure.

Very thin material layers (<100 microm) partially absorb ionizing radiation of low energy. When irradiating monolayer cell cultures from above, attention must be paid to absorption by the medium. Frequently, the volume of the nutrient medium is variable, and this leads to differences in the radiation doses delivered to the cells. In the present work these conditions were investigated for x-rays of energies between 13 kV and 100 kV in comparison with 60Co gamma rays using chemical dosimetry to measure the absorption by liquid layers between 25 microm and 500 microm thick. When the dose as measured with the ionization chamber was held constant, the dose absorbed in the Fricke solution was shown to increase with decreasing thickness of the layer of liquid because of a dose gradient. The effect of the dose gradient disappeared, however, in thick liquid layers of the Fricke solution by mixing during spectrophotometry. Secondary (photoeffect and Compton) electrons produced in air or filters are responsible for this effect in plastic petri dishes where back scattering at the interface does not occur. This interpretation is suggested by the same results of an analogous experimental setup using gamma rays with a 5-mm-thick Perspex plate. This dose increase in very thin layers, however, could not be verified by irradiating monolayer cells in poured-out plastic petri dishes because the secondary electrons are already absorbed in the remaining liquid film above the cells.

Intraoperative radiation techniques allow an additional local dose in areas at high-risk for local failure. With brachytherapy techniques, perioperative radiation can be fractionated. Fractionated treatment might offer an interesting alternative to a single dose, both to increase the therapeutic ratio and to protect late reacting tissues at risk. The dose distribution for brachytherapy applicators can be optimized using spacer materials. In this prospective study a new tissue equivalent bendy applicator (TEBA) that can remain in situ for several days is introduced, and the feasibility of fractionated perioperative high dose rate (HDR) brachytherapy is examined. 31 patients with different tumours (soft tissue sarcoma, Ewings sarcoma, rectal cancer, and locally infiltrating diseases) were treated. The TEBA was applied, depending on resection status and intraoperative findings. Planning was based on digitized radiographs and CT scans. Perioperative HDR brachytherapy was performed using an individual treatment schedule. In 29 patients perioperative radiation was given and in 26 cases fractionated brachytherapy application was possible. TEBA application time varied from 1 day to 11 days. During this time between 1 and 8 fractions were given with total doses from 10 Gy to 25 Gy. Fractionated perioperative brachytherapy with this technique is feasible and adequate. Further studies will show whether fractionated perioperative treatment using the TEBA technique fulfils its theoretical advantages over single dose intraoperative radiotherapy by decreased late toxicity and increased local tumour control.

Background: A variety of solutions are used to match tangential fields and opposed lymph node fields in irradiation of nodal positive breast cancer. The choice is depending on the technical equipment which is available and the clinical situation. The CT simulation of a non-monoisocentric technique was evaluated in terms of accuracy and reproducibility., Patients, Material and Methods: The field match parameters were adjusted virtually at CT simulation and were compared with parameters derived mathematically. The coordinate transfer from the CT simulator to the conventional simulator was analyzed in 25 consecutive patients., Results: The angles adjusted virtually for a geometrically exact coplanar field match corresponded with the angles calculated for each set-up. The mean isocenter displacement was 5.7 mm and the total uncertainty of the coordinate transfer was 6.7 mm (1 SD). Limitations in the patient set-up became obvious because of the steep arm abduction necessary to fit the 70 cm CT gantry aperture. Required modifications of the arm position and coordinate transfer errors led to a significant shift of the marked matchline of > 1.0 cm in eight of 25 patients (32%)., Conclusion: The virtual CT simulation allows a precise and graphic definition of the field match parameters. However, modifications of the virtual set-up basically due to technical limitations were required in a total of 32% of cases, so that a hybrid technique was adapted at present that combines virtual adjustment of the ideal field alignment parameters with conventional simulation.

The relative biological effectiveness of 14 MeV neutrons in the low-dose range < or =1 Gy has been determined in differentiating and differentiated spermatogonia. Male NMRI mice were exposed to single doses of 2 cGy to 3 Gy of (60)Co gamma rays or neutrons. The ratios of testicular S-phase cells, 4c primary spermatocytes, and elongated spermatids were quantified by DNA flow cytometry 2 to 70 days after irradiation and were found to decrease. Histological samples and testis weight were analyzed in parallel. Doses of 2-5 cGy neutrons and 10-50 cGy gamma rays significantly (P<0.05) decreased the proportions of S-phase cells, spermatocytes and elongated spermatids at 4, 14 and 28 days postirradiation. For S-phase cells, the biphasic shape of the cell survival curves was described with a D(50) of 5 cGy neutrons. The D(50) for (60)Co gamma rays and the relative biological effectiveness could not be determined. The relative biological effectiveness of neutrons at 50% reductions of testis weight, primary spermatocytes, and elongated spermatids were 2.5, 10.0 and 6.1, respectively. This in vivo assay is interesting because of its sensitivity at dose ranges that are relevant for exposures in the environment, the workplace and radiotherapy.

Background: More than 300,000 pacemakers are implanted worldwide. During radiation therapy a damage of the pacemaker electronic is possible., Methods: Twenty pacemakers have been irradiated with photons or electrons experimentally in three different situations: a) pacemaker and pacemaker electrode outside of the irradiation field: b) pacemaker outside, pacemaker electrode inside the irradiation field; c) all things inside the irradiation field., Results: The voltage in the pacemaker electrode produced by the electric field of the accelerator did not exceed 0.8 mV if the electrode was outside the irradiation field. Induced voltage was up to 1.2 mV during irradiation with electrons (18 MeV) and the electrode being inside the treatment field with more than two thirds of its length. After delivering of not more than 10 Gy (photons) to the pacemaker, a decreasing amplitude of the pacemaker pulse occurred. The pulse frequency did not show any deviation. This seems to signal a severe early irreversible damage of the pacemaker that may cause sudden breakdown days or weeks after radiation. Two pacemakers showed a complete breakdown after irradiation with not more than 10 Gy. The others had a complete breakdown beyond doses of 50 Gy., Conclusions: It is recommended to keep CMOS pacemakers outside the treatment field and to explant if the dose to it was higher than 10 Gy.

All five fast neutron therapy centres in Germany use low energy cyclotrons or neutron generators and are, therefore, at the low energy end of the 21 neutron therapy facilities presently in use worldwide. The depth dose characteristics are worse than for 60Co gamma rays, the absorbed dose rate is too low and the treatment is technically restricted because of the lack of those modern features like multileaf collimators and full gantry rotation that are available with modern linear accelerators. A survey of the statistical and methodical data on the neutron treatment in Germany is presented. To avoid masking the potential biological benefits of high LET neutron irradiation by the use of suboptimal equipment and to utilise the real therapeutical benefit for specific tumor types, the German neutron therapy centres urgently need modernization of their outdated facilities. Specific recommendations of how to meet the requirements of modern neutron therapy are given.

The advantage of microfocal X-ray units is the production of high-resolution magnification radiographs. Up to a magnification of x 4 the exposure equals that of a conventional radiograph. Some filter materials have been tested, aluminium filtration was found to be the best choice.

The usefulness of direct radiological magnification is inversely related to the resolution of film-screen systems when very small focal spots are used. Thus, spatial resolution of digital luminescence radiography (DLR) may closely approximate that of high-detail screens at the expense of a more restricted field of view. Apart from the major drawback of limited spatial resolution, DLR makes it possible to take full advantage of image-processing techniques and an unmatched dynamic range.

For the conventional X-ray therapy the Röntgenverordnung demands the examination of the dose rate in the radiation beam. The measurements and the results are demonstrated. Over a long period the X-ray equipment shows a constant dose rate. Controls of the technical devices and situations of danger are explained.

Using phantoms of children simulating a child of 6 month of age and another one aged 6 years, the authors measured the amount of radioexposure of the lens of the eye, the thyroid and of the gonads. The two computer tomographs Somatom SF and Tomoscan 300 under examination, produced radiodoses of comparable magnitudes. Both devices allow additional examination techniques of particularly high economy. It was found that in cranial CT the exposure of the lens to radiation is generally below 1 R if the orbitae are not situated in the plane of section. If a distance of 2-3 cm is maintained from the orbitae, the dose remains below 0.5 R. Protecting the gonads is meaningful in a 6-year-old boy, whereas covering-up of the thyroid reduced the dose only slightly.

In ambitious radiotherapy with individually shaped irradiation fields, high-contrast field radiography is necessary for fine adjustment, control and field documentation. If intensification foils made of materials with medium or high atomic numbers such as copper, iron and lead are used, the film lying between the foils is mainly darkened by the secondary electrons released from the material of the front foil. Within the range of 1 MeV to 15 MeV, high-contrast radiographs are produced by means of copper or steel foils which are clearly superior to lead foils. Steel foils are to be preferred to copper foils because of their rigidity and the firmness of the polished surface. Usual X-ray diagnosis films with steep graduation can be used as film material for field control radiography performed in double exposure technique. A new insensitive film not applied hitherto in X-ray diagnosis allows to prepare field documentation images of high quality which are exposed during the whole irradiation time. This is also important for perpetuation of evidence.

An incident with a high-voltage generator more than 25 years old was the occasion for a discussion of the safety of such generators. A control timer broke down during the exposure period, and before the radiographer was able to react the X-ray tube imploded. The young patient suffered increased exposure and partial grade 3 burns. If such a breakdown occurs during exposure the radiographer has to turn off the generator by hand. This is the only way of preventing injury to the patient. Owners of such units must be aware of their particular responsibility and should train their personnel accordingly. In case of a breakdown only well-trained staff can act immediately, in the knowledge that only a few seconds are available before the patient suffers physical injuries. The fault mentioned should have been expected and it could happen again any time with such an old installation.

In 350 patients with 870 pathologic findings comparative blind analysis of conventional chest films and biplane 100 mm photofluorographic images taken with the large-field image intensifier revealed high accuracy in the evaluation of coin lesions, hilar and pleural pathology, pulmonary vasculature and the right paratracheal stripe. Moderate central interstitial edema, more subtle interstitial changes particularly in the lung periphery including Kerley's B-lines, and calcifications in the hilum or the aortic arch are not visible in all cases for the evaluation of lesions of the ribs special films continue to be mandatory. Lateral views are of good quality. The spatial resolution of the large-field image intensifier was measured to be 4.5-5.2 LP/mm at the output phosphor, the spatial resolution of the 100 mm intensified images ranges from 2.6-3.8 LP/mm in the center. Mean skin dose was found to be 6.3 mrd in the p.a. projection which is less than 5% of the values registered in non-intensified photofluorography and even by factor 5 lower than in conventional chest x-ray using rare earth screens.

Microfilming of X-ray films has become more topical owing to the amendment of the X-ray regulations. The storage of X-rays as reproductions on an image or data carrier is expressly envisaged as a possibility in the text of the regulation. The quality of transfer must be insured and the copies must be legible. In microfilming, the latitude and the resolution capacity of the microfilm and remagnification are appropriate as parameters of image quality. Testing of seven filming systems shows a major range of variation of both parameters; in some cases, the results led to reexamination of the camera adjustment and developer chemistry. A test of constancy of filming analogous to direct radiography appears necessary. A corresponding norm does not exist at present.

The palliative effect of treatment stands in the first place in radiation therapy of the esophageal carcinoma. Clinical and roentgenolocical features before and after radiation therapy are reported for 172 patients having been treated under high-voltage conditions between 1962 and 1977. The response of the tumor to irradiation is largely dependent on the tumor shape as visible in the radiograph. In case of tumors growing in polypous shape, often a regression of the tumor is observed even after low doses. An effect beginning later but frequently lasting for a longer time is found with tumors of circular stenosing and diffusely infiltrating growth. All in all a temporary dilatation of the tumor stenosis was achieved in 52% of the patients. Serious side effects of the radiation treatment rarely were observed.