A digital medical X-ray diagnostic device

Abstract

Progress in high energy physics requires the design of detectors of elementary particles to be updated continuously. Presently available detectors of elementary particles are equipped with from tens to hundreds of thousands of channels for detection and identification of particles and radiation modes. The experimental methods of nuclear physics that provide a basis for detection technology have been actively developed over recent decades. Therefore, it is quite attractive to apply the achievements in detection technology to medical X-ray diagnosis; for the last 100 years medical X-ray diagnosis has been almost exclusively based on X-ray photography alone.Recent progress in computer tomography and methods of mathematical processing of digital images gave rise to digital radiography. Methods of digital radiography can be substantially improved ff indirect methods of digital imaging (sampling of Xray photographs, video signal, eta) are replaced by direct detection of X-ray radiation with detectors on-line connected to computers.In the early 1980's, most appropriate devices of that type were so-called multiwire proportional chambers; these were developed by Prof. Sharpack in the 1970's and widely used in high energy physics. It should be noted that Prof. Sharpack was awarded the Nobel Prize in 1992 for the invention of proportional chambers.As expected, if X-ray film is replaced by a proportional chamber modified for the purpose of radiography (photon counting mode, high quantum efficiency, etc.) this allows the radiation load on patients to be significantly reduced, digital images to be obtained, computer technologies to be easily adapted, and X-ray imaging quality to be improved significantly.The first digital X-ray diagnostic device was developed and tested at the Institute of Nuclear Physics, Siberian Division, Russian Academy of Sciences in 1984 [2]. This device was purchased by the All-Union Center for Maternity and Child Health (Moscow) in 1984. The device was updated in 1987 [3]. The second device for examining patients in lying position was purchased by the Center in 1990. The device design and performance were improved significantly in the following years: spatial resolution was increased, the size of the frame was expanded, and efficiency of detection of X-ray radiation was improved [1]. Four similar devices were manufactured in 1994-95. These devices presently work in Moscow, Novosibirsk, and Paris clinics.The MTsRU Sibir low-dose digital (filmless) X-ray diagnostic device consists of a standard source of X-ray radiation, a high-voltage power source, a support with mechanical scanning system, an X-ray detector, and a control unit (Fig. 1). Radiation distribution along the horizontal axis is measured with a proportional chamber and in the vertical direction by mechanical scanning. To implement this, an X-ray tube, a slit collimator, and a chamber are synchronously and uniformly moved in the

Specific features of design and application of digital X-ray apparatuses for examining lungs

“…Male and female gonads are exposed only to stray radiation. A considerable body of experimental data on radiation loads during X-ray examinations of various organs is reviewed in [8]. These data estimation of the effective dose from the value of surface exposure dose taking into account the doses absorbed by the organs exposed to radiation.…”

“…The effective dose is a close of uniform radiation of the whole body with the same probability of postradiation aftereffects as the actual dose of radiation received by a given organ. The total effective dose H E can be determined from the following equation [8]:…”