Vladimir Klonov - Electrotechnical University ''LETI'', Professor Popov street h. 5, Saint-Petersburg, Russian Federation
Ivan Larionov - Electrotechnical University ''LETI'', Professor Popov street h. 5, Saint-Petersburg, Russian Federation
Nikolay Potrahov- Electrotechnical University ''LETI'', Professor Popov street h. 5, Saint-Petersburg, Russian Federation
The usage of X-ray radiation in modern neonatology makes a significant contribution to the quality of medical care for newborns with pathologies. High-quality image of the baby allows to quickly diagnose the problem or to prevent future possible complications.
The method of contact diagnostics (see fig.1) gives satis- factory results, however, to obtain informative images should take into account the following restrictions:
- A large distance between the radiation source and the object of study. This condition is dictated by the need to distance the radiation source to reduce the blurring of the edges. It is necessary to use sufficiently powerful sources to work around the dynamic range of the receiver (which leads to the maximum contrast of the image). Increased tube current causes an increase of the focal spot. Its size directly affects the degree of outer edges blur on the im- age, which is unacceptable in the case of medical diagno- sis. Compensation for this phenomenon is increasing the distance between source and receiver. This can lead to unwanted additional exposure of medical staff and others patients.
High resolution X-ray detector. Upon contact of an ob- ject and a radiation receiver, the image quality depends on resolution of the receiver. However, increasing resolution naturally reduces sensitivity of pixels (by reducing their geometry sizes). This eventually leads to the necessity of increasing power of the radiation source.
High power X-ray radiation. Increased distance source- object and high resolution of the receiver lead to signifi- cant increase in power of X-ray diagnostic machine. Tra- ditionally, the radiological diagnosis in neonatology and pediatrics using radiation sources with power up to 5 kW, which is directly related to their size and weight. From the point of view of stationary use it's not a big deal. Howev- er, for portable options, which work in conditions of con- stant transportation, this factor is essential.
Thus, of use of X-ray machines in non-specialized condi- tions, for example when you need to do diagnostic imme- diately after the procedure of childbirth is in the room of the maternity ward, the use of classical X-ray machines, described above, is not optimal. The basic idea, which is based on an alternative approach to the diagnosis of new- borns is the use of smaller power sources with reduced size of the focal spot of the radiation source. The decrease in its value up to 0.3 mm or below will allow to diagnose newborns under appropriate conditions with scaling method (see fig. 2). Decrease focal spot is achieved with a small current of the tube and using additional focusing electrodes. The lack of dose is compensated by minor (20 – 30%) increasing of operating voltage and decreasing of shooting distance. As a result, while maintaining the qual- ity of the image this approach provides the following ben- efits:
- Resolution of the receiver can be reduced. This leads to the best sensitivity.
- Source-object distance is reduced, which minimizes exposure of staff and others, and also reduces requirements on the output power.
- Relatively low power (360 – 500 W) of radiation source reduces weight and size of the device, which greatly simplifies its use in unsteady conditions .
In this paper, the circuit and structural features of lowpower portable apparatus for neonatology, its internal structure and organization of electronic modules are introduced.
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