[A new biological irradiator for the laboratory]

The use of high doses (15-20 Gy) of X- or gamma-rays to irradiate blood-derived materials is a common practice by now. It is usual especially when materials must be transfused into non-immunocompetent patients. This is done to avoid the so-called GVH disease. Nowadays, for this purpose, units containing radioactive gamma-emitting sources with high activity and long half-life (usually 137Cs) are on the market. The characteristics of these "irradiators" allow their implementation in any laboratory with no need of structural shieldings. In spite of it, serious accidents (e.g., fire, fallings, etc.) which could imply hazards for the operating staff and even the general population, cannot be excluded. At the same time, the problem of long-term disposal of exhausted sources cannot be neglected. For these reasons, a new type of self-shielded irradiator was designed. It is equipped with an X-ray tube, operating at nearly 200-kV voltage, with 12-mA anodic current. The system is water- and oil-cooled and can work for a long time without thermal overloads. In this paper, the environmental and dosimetric measurements for beam characterization are reported. The system can produce beams with satisfactory characteristics for this specific problem. Moreover, its use may greatly reduce administrative radioprotection problems.