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Biomedical subjects

F Nüsslin

Publications and source records attributed to F Nüsslin.

At least 73 records · Page 4Linked to original sources
PubMed1980

Measurements on the radiation protection of patients irradiated with an 18-MeV electron linear accelerator.

In order to quantify the influence of some physical and geometrical treatment parameters on the stray radiation dose absorbed by patients undergoing radiotherapy on an 18-MeV linear accelerator, dose distributions were measured in a polystyrene phantom by means of LiF-dosimeters. For 10-MV X-rays, 6-MeV and 18-MeV electron radiation dose profiles, depth dose and isodose curves were obtained at various field sizes and treatment couch positions. By covering the phantom with 1 or 2 mm thick lead sheets a remarkable dose reduction was found. A two-exponential expression was derived to estimate stray radiation dosage in routine radiotherapy. The validity of the calculation method was demonstrated by comparing the gonadal load measured in an Alderson phantom with the calculated data.

Lead↗
PubMed1979

[Dose measurements during mammography using a grid (author's transl)].

In order to increase film contrast, the Mammo Diagnost U (Philips) has been equipped with a newly developed grid. The apparatus was used with a film-screen combination in a clinical investigation (film: 3M type M, screen: Kodak Min R, cassette: Kodak Min R). The paper deals with dose measurements on patients and phantoms who had been x-rayed by the apparatus. Measurements were carried out with a low kv. chamber and a LiF dose meter which were calibrated for various kv. ranges. The tissue equivalent phantom was a modification of the phantom substance M3; this was preferred to the usual substances such as Plexiglass or Vestyron because of its more suitable physical properties. A breast compressed to 5 cm. irradiated with 35 kv. receives an entry dose of about 1.4mC/kg. (5.3 R) corresponding to a maximal surface dose of about 31 mGy (3.1 rd.). In order to determine radiation dose to patients, measurements were carried out on an Alderson phantom using four different techniques. Surface dose to the contralateral breast and the lens was about 1% and .1% of maximal surface dose of the irradiated breast. Gonadal dose was less than 0.4 muGy (40murd.) per exposure.

Female↗
PubMed1979

[Clinical experience with mammography using grids (author's transl)].

Duplicate examinations were carried out on 122 patients in order to compare the results of mammography using a grid technique (Diagnost U. Müller) with a film-screen systemadn also a conventional set without screens (Mamma-Diagnost, Müller). The results were compared with reference to film quality and dose. The new technique was superior to the conventional method in all respects, independent of the size of the gland. Another advantage of the grid technique was the larger available film size. Dose requirements for grid mammography with a film-screen system was less than for conventional techniques by a factor of about 1.8. The results speak for increased use of the grid technique in clinical practice.

Breast Neoplasms↗
PubMed1979

The Clinac-18 linear accelerator. 10 MeV photon beam data.

Measurements were carried out on a Clinac-18 linear accelerator in order to characterize the 10 MeV photon beam. Depth dose data and tissue-maximum-ratios were obtained for field sizes up to 35 x 35 cm2. Using a parabolic expression a least square fit to the tissue-maximum-ratios was performed. The radiation field flatness and the penumbra were found to be in good agreement with the tolerances recommended by the IEC standard (draft). The radiation field and the light field isocentre were determined as suggested by the IEC. The distance between both isocentres was less than 1 mm.

Particle Accelerators↗
PubMed1979

[Radiation therapy of humeroscapular periarthritis (author's transl)].

The effectiveness of radiation therapy in 233 cases with periarthritis humeroscapularis is reviewed in a prospective study from the Basel canton hospital. The patients are studied with regard to different parameters, such as duration of the anamnesis, importance of the dose, moment of evaluation of the results and influence of a 2-series technique. The total result, comprising 43.3% cases without complaints, 30.9% being better, and 25.8% whose troubles had not changed, is compared with the compiled statistical data of 4957 cases found in literature. The gonadal load is discussed on the basis of our own investigations.

Gonads↗
PubMed1979

[Measurement on a 42-meV betatron with regard to the radiological protection of patients (author's transl)].

In order to examine the side radiation field of X-rays from the 42-meV Siemens betatron, transverse and depth dose distributions were measured in the phantom with LiF dosemeters. The influence on the dose distribution exerted by the kind of radiation and its energy, the rotation angle of the patient's table, and the field dimensions was determined. The quality of the side radiation and the effect of additional lead shieldings were examined. The dose distributions can be calculated approximately by means of an exponent which can be used in order to estimate the surface dose for all desired irradiation conditions and to determine any distances from the field edges.

Humans↗
PubMed1979

[Influence of radiotherapy upon tumor accumulation and organ distribution of 57Co-bleomycin in mice with chemically induced squamous cell carcinoma (author's transl)].

Squamous cell carcinoma was induced in male 6 to 8-week old NMRI-mice by application of 9,10-dimethyl-1,2-benzanthracene on the skin. 15 weeks later macroscopically visible skin tumors are developed. Then organ distribution and tumor accumulation of 57Co-Bleomycin (spec. activity 1 mCi/3.3 mg) were studied 1 to 48 hours after injection. In squamous cell carcinoma a high uptake of this tumor-seeking agent can be demonstrated (n = 46). After radiotherapy (100 kV; 1.7 mm Al-filter; 18.8 Gy) (n = 26), however, a significantly reduced uptake of 57Co-Bleomycin in tumor tissue is observed. Possible consequences from these animal studies for tumor scintigraphy with this radiopharmaceutical in man are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

[Dose reduction during radiological examination using high intensity rare earth screens or increased kV (author's transl)].

Using a procedure which resembles actual practice, it has been shown that an increase in kV. results in a reduction of radiation dose similar to that obtained by using the new high intensity rare earth screens while maintaining similar detail. In practical terms this means that there is only limited usefulness for the new rare earth screens. An exception to this is the screen which reduces dose while producing similar, or better, detail than a standard screen. We could demonstrate this for the film-screen combination Trimax alpha4XD.

Humans↗
PubMed1976

[The irradiation of air-filled cavities in a plexiglass phantom using 42 MiV bremsstrahlung].

For the investigation of dose distributions as they are produced by the existence of cavities within the irradiated volume, a nonhomogeneous plexiglass phantom has been exposed to a 42 MeV radiation due to retarding of particles. Depth dose curves as well as the ion dose of the interface being more distant from the focus have been measured using different dimensions and depths of the cavity. The modifications of the dose distribution are essentially due to the density difference producing the displacement of the depth dose curve and to multiple scattering effects. The displacement of the depth dose curve amounts to about two thirds of that dimension of the cavity which runs parallel to the radiation axis. An increase or a decrease of the ionization within the air-filled volume results from multiple scattering effects and in dependent on the shape of the cavity.

Air↗
PubMed1976

[Gonadal load in the radiotherapy of benign diseases. I. Degenerative joint diseases].

The gonadal load was measured during radiation therapy of humeroscapular periarthritis, coxarthrosis, diseases of the vertebral column and of the sacro-iliac joint (disease Bechterew) for different irradiation techniques. All measurements have been performed by LiF dosimeters and with an Alderson phantom using 250 kV X-radiation. The gonadal dose with respect to the surface dose was in the range of tenths of one per mill in case of humeroscapular periarthritis and reached values up to about 30 per cent in coxarthrosis and Bechterew disease. Measurements during irradiation of the vertebral column yielded most differing values of the gonadal load depending on gonadal distances from the region exposed.

Arthritis↗
PubMed1976

[Gonadal load in radiotherapy of benign diseases. II. Infectious diseases and keloids].

The irradiation damages to the gonads caused by the radiotherapy of parotiditis and mastitis and of cheloids was determined partially under different irradiation methods. The measurements were effected with LiF dosimeters in the Alderson phantom with a tube tension of 250 kV for the inflammatory diseases and 55 kV for the cheloids. The gonad dose measured at the surface was within the range of hundreths of permille for the parotiditis, for the mastitis is was between tenths of permille and 2% depending on the therapy method. The gonad dose of the cheloid irradiations showed a clear relation to the distance between radiation source and gonads. The importance of radiological protection is emphasized.

Female↗
PubMed1976

[Gonadal load in 60Co irradiation of peripheral, mediastinal and retroperitoneal lymph nodes].

A telecobalt therapy of lymph node groups was simulated on the Alderson phantom and the gonad dose caused by each irradiation field was measured with LiF dosimeters. When the supradiaphragmatic and the para-aortal lymph nodes were irradiated, the ovary dose showed rates up to 20% of the dose maximum. The irradiation of the same zones brought about a testicle dose of less than 50% of the dose maximum, and only 1/20 of this rate was achieved when a lead plate of about four cm was used in order to protect the testicles. The results are discussed under the point of view of the genetic risk.

Cobalt Radioisotopes↗
PubMed1975

The influence of air cavities on the dose distribution of high-energy electron beams.

A Lucite phantom containing cylindrical air cavities was irradiated with high-energy electrons from a betatron. By measuring depth-dose curves, the relative enhancement in electron fluence adjacent to the cavity on the side opposite to the beam entrance was determined as a function of the initial electron energy, the dimensions of the cavity and its depth in the phantom. The enhancement factor was found to be critically dependent on energy, the height of the cavity and its depth in the phantom, but to a lesser extent on its diameter. The experimental results have been compared with calculations based on multiple scattering theory.

Air↗