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Biomedical subjects

K Kuphal

Publications and source records attributed to K Kuphal.

14 recordsLinked to original sources
PubMed1991

[The dosage calculation of very small irregular electron irradiation fields. 2. The dosage distribution at the edge of the field].

Cross beam dose distributions of the small square electron fields (1 x 1 to 6 x 6 cm2), used in the first part of this paper, have been measured at a linac equipped with metal diaphragms attached to a closed cone. They have been used for calculation of the mean square radial displacements sigma 2 of the corresponding pencil beams. Due to complicate electron scattering at the cone and the diaphragm, the pencil beam method could not be used with the simplicity and accuracy desired in practice. Therefore, the therapeutical sufficient field widths, field areas and integral doses have been determined directly from the measured dose distributions, and are represented in dependence from the geometric field size. For small fields we found considerable reductions of these values, which, in practice have to be compensated by enlargement of the geometric field size.

Electrons↗
PubMed1990

[Dose calculation for very small irregular electron beam fields. 1. Dose calculation for the central beam using a simple field zone method].

Very small electron beams show considerable reduction of the dose output factor, the therapeutically relevant range, the practical range and the therapeutically relevant field size, compared to broad beams. The first three effects were measured on the central beam axis for different quadratic field sizes and are presented in the first part of this publication. A simple field zone method for calculation of irregular shaped electron beams was developed from the different depth dose curves. The method allows the determination of the maximum dose and the 80% range with sufficient accuracy for practical purposes. The examination of the reduction of the therapeutically relevant field size and the consequences following thereof with respect to the adequate electron therapy of a small irregular target volume will be published in a second part.

Electrons↗
PubMed1989

Gamma irradiation as a substitute for H2O2 in peroxidase-labelled enzyme immunoassays.

The ability of gamma irradiation to substitute for H2O2 in peroxidase-labelled enzyme immunoassays was investigated. Colouring of TMB (3,3',5,5'-tetramethylbenzidine), ABTS [2,2'-azino-di(3-ethylbenzthiazoline-6-sulphonic acid)], and OPD (o-phenylenediamine) was produced with doses of 10 and 20 Gy. Addition of superoxide dismutase enhanced TMB and ABTS, and inhibited OPD. The reaction was terminated when the irradiation was stopped. The use of denaturing compounds to stop the reaction was unnecessary and coated antigens could be re-used for a second immunoassay.

Free Radicals↗
PubMed1986

Dosimetric problems associated with total body irradiation.

Total body irradiation (TBI), which is carried out with high energy photons at large source distances and with large fixed fields, involves special dosimetric requirements. The dose measurements published thus far on anthropomorphic phantoms have shown that deviations from the dose values calculated with "normal" dose functions occur as a result of completely different scatter radiation distributions. The higher the photon energy selected, the more slight these deviations become.

Humans↗
PubMed1986

[Treatment of symptomatic mucinosis follicularis in mycosis fungoides using fast electrons].

Mucinosis follicularis is a chronic type of dermatosis involving the sebaceous glands and outer root sheaths, which can be differentiated into primary and secondary types. The latter - also called symptomatic mucinosis follicularis - causes therapeutic problems because of the underlying malignant lymphoma. Successful treatment using electron beams supported by etretinate is described in detail in a 40-year-old man with symptomatic mucinosis follicularis based on plaque-type mycosis fungoides. After 6 months free of skin symptoms, the mycosis fungoides lesions recurred in the overlapping borders of the irradiation fields. These lesions were treated again with electron beams. A relapse after 32 months was controlled by PUVA. Electron beam therapy is recomended in the plaque type of mycosis fungoides, especially if PUVA has no effect for some reason.

Adult↗
PubMed1985

[Dose rate constant and radial dose function of an iodine 125 radiation source in various substances].

The dose distribution around an isotropic, point radiation source can be expressed by the dose rate constant, the quadratic law of distance, and a radial dose function which depends on the absorption and scatter processes occurring in the surrounding material. The radial dose function and the dose rate constant of a point iodine-125 source can be represented in a clear and rather exact manner as simple functions of the linear attenuation and energy absorption coefficients, because the average photon energy does not considerably vary with the growing distance from the source. This representation is in contrast with some functions defined in a distance of 1 cm, in conformity with the definition of the dose rate constant in the air according to DIN 6814, part 3.

Air↗
PubMed1982

Interstitial radiotherapy with 198Au seeds in the primary management of carcinoma of the oral tongue: results in Freiburg/Breisgau from January 1964 to July 1980.

Thirty-two patients with histologically proven carcinoma of the oral tongue, Stage T1-3, were analyzed retrospectively. They were treated from January 1964 through July 1980 in Freiburg by interstitial implantation with Au-198-seeds for the primary tumor management. Out of 25 patients with complete follow-up, one patient developed a local recurrence. In three patients, regional lymph node metastases occurred, once after prior adjuvant radiotherapy to the regional lymph nodes area, and in two patients after exclusive interstitial radiotherapy to the tumor of the tongue. The overall five-year survival rate was 52% for all stages (overall group), 75% for Stage T1 and 44% for Stages T2-3. The corrected five-year survival rate was 75% for all stages, 86% for Stage T1 and 71% for Stages T2-3. The method of 198Au-seed implantation as it is practiced in Freiburg is discussed, as well as the radiation exposure of the personnel.

Adult↗
PubMed1980

5 years of operation experience with a 4 MeV linear accelerator in radiotherapy.

The results of our experience in operating a 4 MeV linear accelerator Clinac 4 from Varian in radiotherapy are reported, especially considering the 12-hours-per-day operation for more than the last 3 years. Frequency of defects of different parts is discussed. The downtime adds up to 6 days per year, service and repair costs amount of US $ 33,--per patient.

Costs and Cost Analysis↗
PubMed1980

[First report of experiences with interstitial radiation therapy of the prostatic carcinoma using 125-I-seeds: indication, practical performance and radioprotection (author's transl)].

The practical and organizing performance of interstitial radiation therapy with 125-I-seeds in prostatic carcinoma is reported. Precautions and measurements for radioprotection are emphasized. First evaluations of these measurements show that this therapeutical technique can be performed in complete accordance with the directive for radioprotection. The computer-assisted isodose-planning and the in-vivo-measurements in the rectum, urethra and bladder confirm the steep decrease of the dose outside the irradiated focal volume. Hence, inflammatory symptoms accompanying the therapy are markedly allayed in comparison with percutaneous radiation therapy, in spite of a higher tumor dose. Because of the extensive operation, attention must be paid to the strict observation of indication criteria.

Brachytherapy↗
PubMed1978

[Present state of the wide-field megavoltage radiotherapy of Hodgkin's disease. Fundamentals, performance, side effects (author's transl)].

Therapeutic results of Hodgkin's disease could be significantly improved by the introduction of megavoltage radiotherapy equipment and more profound knowledge about this disease. By this way, five year survival rates of 70% can be achieved for all stages and up to 100% for the early stages. The wide field technique enables the coverage of all lymph nodes with protection of non involved organs. Simultaneously, these improved technical conditions make optimal radiation planning necessary which demands numerous technical auxiliaries. Radiation type and radiation energy are important preconditions for the therapy; production and usage of shilding blocks are necessary for individual performance. The principle for optimal radiation dose distribution are measurements and calculations on the phantom which are now included in computer programs. Nevertheless, radiation of large volumes represent a high stress for the patient. Despite the improvement of the therapeutic results there are except the acute radiation side effects, also irreversible alterations. These can be analysed only after long time observations and has to be balanced with the therapeutic results. The knowledge of these side effects is very important for the radiologist. Beside that, the risk of induction of a second tumor has to be considered. The present possibilities of absolute control of this disease enables the overtreatment of lesions in the early stages. Therefore it has to be postulated to regard the present therapy concepts with attention and to consider the possible side effects.

Acute Disease↗