ПРОБЛЕМИ ЯКОСТІ ПЛАНУВАННЯ ПРОМЕНЕВОЇ ТЕРАПІЇ НА КОМП’ЮТЕРНИХ СИСТЕМАХ

The urgency of the problem. Determination of absorbed dose in the planning and radiotherapy is one of the factors ensuring the quality of care a cancer patient. Today for planning radiation therapy, the most widely used data obtained by x-ray computer tomography (CT). The CT analysis showed that different patients under the same conditions, the measured «eFilm» program instruments, the same objects have different pixel sizes and optical density. The purpose of the study is to identify the hidden reserves of an effective radiation treatment planning of cancer patients by accurately determining the dose, taking into account the pixel size (voxel) and density inhomogeneities, as well as the correct measurement of the image data of DICOM files for CT program «eFilm». Object of study: the properties of the pixel and its derivatives determined by the program «eFilm» and calculated way. The materials and methods. RCT conducted in patients with brain tumors, for CT scanner Toshiba Asteion super 4. Evaluated cross sections data of RKT, with a thickness of 1,5 mm reconstruction of each slice, the program processing DICOM files for CT – «eFilm» «Phillips Medical MXLiteView Version 1,22 MS». It was determined the pixel size, the number of pixels in a predetermined size, the selected area of the image area and the optical density of different areas of the image. The pixel size was calculated by dividing the length of the image on their number. The calculation of the length of the image was determined by multiplying the number of pixels for their size. The area of the image to calculate the product of the pixel width by its length and quantity. In addition to the tumors was determined by optical density of different areas of the cut out image of the object of study (black background). Results and discussion. The pixel size, the length of the selected image and the area defined by the program is «eFilm», rechecked manual arithmetic way. The pixel size is calculated by hand, made of 0,45 mm. Program defined – 0,4 mm. The difference is more than 11 %. Image length was 4 mm. Program was determined to be 4,5 mm. The difference is more than 11 %. The image area is 1,5 mm2 . Region in the framework of the program – 2 mm2 . The difference is 20 %. A variety of pixel sizes in one cut makes it hardly possible to correctly study the properties of the object the image of which is presented in a similar view DICOM file. When determining the optical density is established, that the outside image of the study area («black background», «zero pixel images»), their values range from –1000 HU» near the boundary of the investigated object, to «-834 HU» at a distance of 7 times further away from him. The presence of portions of dissimilar densities outside the image slice, against the background of «absolute zero», do not exclude the possibility of the same artifacts and in the main object image slice of the object. It may have a negative impact on the results of determining changes in the study area, as well as on the development of a plan for follow-up treatment, including radiation, if the basis will be based on incorrect data. Thus, the analysis showed that a large degree of uncertainty of the obtained results, makes it extremely difficult using the tools of the program «eFilm» to solve practical and scientific problems in medicine. In this regard, one of the reserves of improving the quality of planning radiation therapy to cancer patients is the improvement of the software processing and analysis of CT DICOM files used for medical purposes.