Biomedical subjects

Z Kolitsi

Publications and source records attributed to Z Kolitsi.

3 recordsLinked to original sources

PubMed1979

Scattered radiation from beam modifiers used with megavoltage therapy units.

The magnitude and distribution of scattered radiation produced by scatterers inserted into megavoltage therapy beams, including the beams from an 8MV medical linear accelerator and a 60Co teletherapy unit, were investigated. The intensity distribution of scatter depends on the distance from the scatterer to the measurement plane (retraction distance) and also, to a lesser extent, on the atomic number of the scattering material. The effective energy of the scattered radiation was determined by depth dose measurements in tissue equivalent material using thermoluminescent dosimeters and was found to increase with photon beam energy.

Cobalt Radioisotopes↗

PubMedDate not supplied

An anatomical filter for exposure equalization in mammography.

An anatomical filter has been designed, tested and subsequently used in clinical practice to equalize optical density over the entire mammographic image, thus eliminating the need for dual exposure whenever both the mammary gland and the peripheral structures of the breast must be clearly visualized. The use of the filter results in a reduction of the optical density, at the peripheral structures of the breast, with a simultaneous increase of the contrast, without causing deterioration of the mammary gland image. Improved visualization of the connective tissue, the skin, the nipple and the subcutaneous adipose tissue is achieved, as well as minimization of the radiation dose to the breast for patients with an indication of peripheral breast lesions.

Female↗

PubMedDate not supplied

A multiple projection method for digital tomosynthesis.

A new method of optimized efficiency for the retrospective reconstruction of tomograms is presented. The method has been developed for use with isocentric fluoroscopic units and is capable of performing digital tomosynthesis of anatomical planes of user selected orientation and distance from the isocenter. Optimization of efficiency has been achieved by segmenting the reconstruction process into discrete transformations that are specific to groups of pixels, rather than performing pixel by pixel operations. These involve a number of projections of the acquired image matrices as well as parallel translations and summing. Application of this method has resulted in a significant reduction of computing time. The proposed algorithm has been experimentally tested on a radiotherapy simulator unit with the use of a phantom and the obtained results are reported and discussed.

Algorithms↗