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Biomedical subjects

U Rosenow

Publications and source records attributed to U Rosenow.

At least 19 recordsLinked to original sources
PubMed1996

Quality assurance in radiotherapy: the importance of medical physics staffing levels. Recommendations from an ESTRO/EFOMP joint task group.

The safe application of ionising radiation for diagnosis and therapy requires a high level of knowledge of the underlying processes and of quality assurance. Sophisticated modern equipment can be used effectively for complicated diagnostic and therapeutic techniques only with adequate physics support. In the light of recent analyses and recommendations by national and international societies a joint working group of representatives from ESTRO (European Society for Therapeutic Radiology and Oncology) and from EFOMP (European Federation of Organisations for Medical Physics) was set up to assess the necessary staffing levels for physics support to radiotherapy. The method used to assess the staffing levels, the resulting recommendations and examples of their practical application are described.

Europe↗
PubMed1990

[A rapid radiotherapy planning program in intracavitary afterloading therapy].

A recently developed program for the irradiation planning of intracavitary afterloading applications in the treatment of gynecological diseases is presented. On the basis of measured data, a rapid algorithm for calculating the dose within the field near to ray emitters is introduced which avoids any uncertainties as to the greatest activity and the dose rate constant. Distance- and direction-dependent corrections of the inverse square law are performed by means of polynomials easy to calculate or by tables. The structure and performance of the program are described. Some examples are given in order to illustrate the possible applications of the irradiation planning program.

Algorithms↗
PubMed1985

125I interstitial brachytherapy for primary malignant brain tumors: technical aspects of treatment planning and implantation methods.

Use of interstitial radiation holds promise in the treatment of primary malignant brain tumors, but optimal technical factors have yet to be determined. We have developed a method of precise CT directed stereotactic placement of radioactive sources in a predetermined target volume. We use low activity (1-2 millicurie/speed) sources of 125I loaded in silastic catheters, which are positioned in a parallel array in the target. Positioning of such multiple sources toward the periphery of the volume enhances achievable dose homogeneity. Seeds of various activities can be differentially loaded into each catheter and the catheters can be positioned at various radii from the central target so that the treated volume corresponds to the identified (often irregular) target volume. Although the implant is designed to be permanent, the sources can be removed easily in a second procedure.

Brachytherapy↗
PubMed1984

A block localizer for easy and reproducible transfer of shielding block positions from simulator to treatment unit.

For the localization of shielding blocks at the simulator a special tray called "block localizer" was constructed. It can be attached to the simulator head by means of magnets in the top frame. The "block localizer" provides a platform at a distance from the X-ray source corresponding to the source-to-block distance at the treatment unit. On the platform templates made from 0.5 mm brass to the size of the block bases can be positioned under fluoroscopy. Before taking the beam localization exposure a low sensitivity film is placed in a slit in the platform. On this film the template (block) position is recorded. For treatment the developed film is attached to the block tray and the shielding block inserted according to the light shadow of the template projected from the film onto the patient. An easy and reliable positioning of blocks during repeated irradiations is thus provided. The block (template) position is also recorded on the beam localization film of the patient as a transparent shadow.

Humans↗
PubMed1983

[Revision of the radium isodose atlas of Göttingen with a new calculation method].

The Radium Isodose Atlas of Göttingen was recalculated after having established a new computer program for the determination of dose distributions around intracavitary radium inserts. The program takes into consideration the complicated structure of the radium applicators type Buchler. The exactness of the program was checked by computing known radium sources and by detailed measures. The calculated dose values were reduced by 30% on an average with respect to the original measurements. This difference is explained mainly by the dependence on energy of the Cds dosimeter used at that time (1959). The clinically evaluated dose has not been changed (identical milligram element hours), however, a comparison of radium doses with other hospitals and with an additional percutaneous irradiation has become possible by the recalculation. Point A has been redefined according to international practice.

Brachytherapy↗
PubMed1980

A simple function describing the absorption in platinum for dose-rate calculations around radium applicators.

The diminution of exposure rate from radium gamma radiation by filtration through platinum can be described very accurately by gamma 0/(1 + mu0d) for wall thickness d from 0.2 mm to 4.0 mm (gamma 0 = 6.356 x 10(-5) A m2/kg2 or 8.869 R cm2 h-1 mg-1; mu0 = 1.501 cm-1). This function fits generally accepted data to within experimental error, to an accuracy not achieved by any single exponential factor. The expression is derived theoretically from a simple approximation to the spectral distribution of radium gamma radiation. With this type of transmission function, the expression for the exposure rate around linear radium sources in platinum tubes (generalized Sievert integral) is readily integrated in terms of elementary functions. Used in place of the Sievert integral in calculations of dose distributions, this new fomulation makes possible straightforward numerical evaluation and avoids the storage of tabulated values in computer programmes.

Absorption↗