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At least 163 records · Page 9Linked to original sources
PubMed1980

[First experience with the electron accelerator "Therac 20-Saturne" in clinical practice. 1st communication: technical data and dosimetry of photon radiation (author's transl)].

The fundamental principles of construction, the operational data, handling and safety devices of the first linear electron accelerator type Therac 20-Saturne (CGR MeV) installed in Germany are described. Relevant characteristics of the radiation field for therapy with 12 and 18-MV photons and also the dosimetric data are reported. Observance of the tolerances recommended by the IEC is guaranteed with this accelerator.

Mathematics↗
PubMed1994

[Radiosurgery with the gamma knife].

The conception of radiosurgery now more than 40 years old is realized in clinical practice during last 25 years. There were elaborated 3 main methods: focused irradiation by gamma knife, by accelerated heavy charged particles and by linear accelerator. The results led radiosurgery spread over the world. The main indications are vascular malformations (44%), benign intracranial tumours (33%), malignant tumours including metastasis (21%) and functional disorders (2%). The pathological lesions can be controlled or liquidated in 80-95%. The hospital story is minimal, 1-2 days, and there is no risk of mortality and morbidity is minimal. Only the time of healing is prolonged to some years with indispensable follow-up. Further technical improvement and growing number of patients treated by radiosurgery can be expected.

Central Nervous System↗
PubMedDate not supplied

Bremsstrahlung review: an analysis of the Schiff spectrum.

A concise approximate formula computed by Schiff for the intensity spectrum of bremsstrahlung photons has been a valuable starting point for many medical physics applications, including the Task Group 21 protocols. This paper provides a brief review of the literature related to determination of the bremsstrahlung spectrum and to the Schiff formula in particular. It describes the approximations Schiff made to obtain this formula, including the Born approximation, and the exponential nuclear screening potential, the infinite-mass nucleus approximation, and the "extreme relativistic" approximation. A derivation of a more exact formula that avoids the last of these approximations is presented. This provides a check on the accuracy of the Schiff spectrum for linear accelerator energies used clinically. Comparisons with the Schiff thin-target result are presented. A thick-target bremsstrahlung spectrum is calculated and compared with the forward spectrum obtained from Monte Carlo simulations of the x-ray production in two linear accelerator treatment heads.

Particle Accelerators↗
PubMed1980

A simple electron cone interlock system for the clinac-18.

A simple electron cone-collimator interlock system has been developed for the Clinac-18. Each cone is assigned a special slot in the storage cabinet and, upon being taken for treatment setup, sends out a binary coded decimal (BCD) signal to the control console. The voltage from the collimator setting must match the BCD signal or a comparator logic will drive the fault matrix to prevent the accelerator from energizing.

Electrons↗
PubMed1983

[Tissue activation by bremsstrahlung from medical accelerators].

If a continuous radiation with a maximum energy of more than 10.55 MeV is used in radiotherapy, there is an activation of tissue. A radiation exposure of the staff may be connected with this activity induced by the nuclear photon effect. The consequences for routine radiotherapy are demonstrated by the examples of a betatron 42 MeV and a linear accelerator Clinac 20.

Humans↗
PubMed1992

Asymmetric field calculations.

A simple method for performing manual dose calculations in asymmetric fields is proposed. The method is based on a generalized central-axis dose calculation equation for which open- and wedged-field off-axis provisions have been made. A calculation form designed to document the calculation and simplify the calculation process is presented. Lastly, the required off-axis dosimetry data obtained from a dual-energy accelerator are shown.

Humans↗
PubMed1983

Electron depth-dose dependence on energy spectral quality.

Electron depth-dose curves and spectra have been measured from an experimental accelerator on which both energy and spectral shape could be varied independently. The measurements were made at nominal energies of 6 and 12 MeV, with the energy spread (FWHM) varied from 1.7% to over 10% of average energy. Changes in depth-dose fall-off characteristics correlated only weakly with the width of the accelerator's spectrum. The use of a single accelerator and experiment set-up eliminated the differences that have complicated previous comparisons of beams of different spectral quality, which have been based upon data from different accelerator designs.

Particle Accelerators↗