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Biomedical subjects

G Schoknecht

Publications and source records attributed to G Schoknecht.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Model calculations of the Energy distribution of scattered radiation in a patient (author's transl)].

To obtain quantitative results on scattered radiation produced in a patient by externally applied x-rays or gamma rays, the model of a pencil beam penetrating a water layer is used. By means of the Monte-Carlo method, the energy distribution of scattered photons in a plane parallel to the absorbing layer is calculated for primary photon energies from 60 to 1250 keV. This yields information on the distribution of single-scatter and multiple-scatter photons.

Elementary Particles↗
PubMed1980

[Influence of depth compensation on the visualization properties of ultrasound image methods (author's transl)].

Due to the enormous absorption of ultrasound in body tissue an amplification of the echo signals, depending to the pulse transit time, is absolutely necessary for ultrasonic measurements. The influence of the adjustment of the depth compensation facility on the imaging characteristics of ultrasonic methods is examined with phantom measurements in water and in mineral oil, which provide a suitable phantom substance for body tissue. The importance of the reflector geometry for the adjustment of the depth compensation facility appears from measurements at a frequency of 2 MHz with a plane and a spherical reflector. The results demonstrate the necessity to adapt the adjustment of the facility to both, the utilized transducer and the respective diagnostic question in order to avoid errors in evaluation. The effects of depth compensation and reflector geometry on the ultrasound image are demonstrated by using a special arrangement of phantomes.

Amplifiers, Electronic↗
PubMed1980

[Investigation of spectral scatter photon fluence of needle ray beams (author's transl)].

Extending the Monte Carlo calculations of the scatter dose distribution of needle ray beams performed earlier, the dose distribution was determined as a function of spectral scatter photon fluence. From the disappearance of dose contributions to certain group fluences there has to be concluded that definite parts of spectral photon fluence also must vanish. The results show the existence of interfaces which are effective for scatter photons with distinct levels of energy. Dependence of the interfaces on the limitation of the absorbing space and on the energy of primary photons is being investigated.

Absorption↗
PubMed1979

[Phantom substances for the simulation of tissue of the soft parts in ultrasonic diagnostics (author's transl)].

The image-transmitting methods using ultrasound are gaining ground in medicine and are being increasingly used alongside the methods of diagnosis based on x-ray film. Whereas the use of phantoms for purposes of measurement and instruction has been common for a long time, there have so far been hardly any suitable phantoms for ultrasound. One of the reasons for this state of affairs is that only very little is known about the materials which are suitable for the simulation of body tissue. Among the physical factors which are important in ultrasonic examination are; the speed of sound, sound impedance, and the sound attenuation coefficient. The article reports on methods for selecting suitable phantom materials, and on measurements at an ultrasonic frequency of 4 MHz.

Absorption↗