[Investigation of the entrance dose of standardized chest radiographs]. / Untersuchungen über die Einfalldosis bei standardisierten Aufnahmen der Lunge.

In 50 chest radiographs obtained in PA projection with the patient erect and the radiographic techniques kept constant, entrance dose, entrance surface dose and dose area product were measured and compared with the measurements obtained with Plexiglas and Alderson phantoms. Following the recommendations of the International Commission on Radiological Protection, the "absorbed dose in air" at the point of intersection of the X-ray beam with the surface of the patient was used as reference. For patients with the same diameter, the measured dose deviated up to +/- 50 % from the "Reference Man" according to the ICRP 23 as well as from the "Representative Patient" according to the ICRP 73. The exposure data produced by the equipment corresponded to the measured values with minor deviations, but the dose values expressed as entrance surface dose showed major deviation in comparison with the entrance dose due to differences in the back-scatter factor. The values of entrance dose calculated from the dose area product measurements showed additional uncertainties due to different field sizes. Moreover, a sex-specific dose area product value was identified. These results reveal that the values of the "ICRP Reference Man" differ in many situations from the values produced by the examined patient due to differences in radiation transmission. This has consequences for determining diagnostic reference values and investigating recorded radiation exposure. This will be explained and substantiated.

[Examination of the constancy of the medium optical density of conventional chest radiographs]. / Untersuchungen über die Konstanz der mittleren optischen Dichte bei konventionellen Röntgen-Thorax-Aufnahmen.

PURPOSE: To determine whether the medium optical density of conventional chest radiographs is constant. MATERIALS AND METHODS: 47 PA chest radiographs were digitized to measure the optical density and its dynamic range of normal and pathologically altered lungs. RESULTS: For constant exposure factors and a correctly positioned region of interest, the medium optical density deviates only minimal despite differences in AP chest diameter, entry dose and dynamic range, and is largely independent of the pathologic pulmonary findings. CONCLUSION: Digitization of the radiograph enables the determination of the physical parameters used to operate the imaging system, such as medium optical density, image contrast, image latitude and density distribution, in accordance to the guidelines of the German Medical Association. If the region of interest encompasses the clinically relevant region of the lung, the measured value of the optical density corresponds with only minor variation to the average value of the entire lung region.

[Critical evaluation of currently recommended "reverence level" values]. / Kritische Bewertung bisher empfohlener Werte von "Reference Levels".

The guidelines of the committee on health protection in medical exposure contain, as required by the international commission on radiation protection, the requirement for the determination of values for reference levels for medical exposure, their use, and their fulfillment. Here we discuss the basis for their determination and point out that their control only appears to be meaningful in combination with quality requirements for which parameters are given in the guidelines of the German Medical Chamber and the European Guidelines.

A new Diamentor for measuring kerma-area product and air-kerma simultaneously.

The new M4KDK Diamentor (PTW-Freiburg) for measuring the air-kerma-area product (KAP) and air kerma (AK) simultaneously was evaluated. The special design of the Diamentor chamber influences the variation of the calibration factor with respect to the field size somewhat differently to what is the case with the classic Diamentor. It is therefore recommended that calibration be performed for a larger field size. If the M4KDK Diamentor is calibrated for a field size of 3.8 cm x 3.8 cm (at the chamber), an uncertainty in the AK value of better than 15% for a field size larger than the calibration field, can be expected. The influence of backscattered radiation on the calibration factor is equivalent to that for the classic Diamentor chamber. The variation in response in accordance with tube potential, is also comparable with that of the classic Diamentor. Dramatic changes in response have to be expected if additional filters are introduced in close proximity to the Diamentor chamber.

[The new x-ray ordinance--responsibilities of those answerable for radiation protection and their delegates, expert knowledge]. / Die neue Röntgenverordnung--Aufgaben des Strahlenschutzverantwortlichen und der -beauftragten, Fachkunde.

The Federal German X-Ray Regulations as amended on 8 January 1987 represent a revision and reformation of the old regulations of 1 March 1973. The new version is largely based on the requisite conclusions resulting from the recommendations made by the International Radiation Protection Commission and the standards of the EC derived therefrom. In this manner the Federal German regulations have been adjusted to conform with European legislation. Other changes effected in the regulations concern mainly the delineation of the responsibilities of the owner of the x-ray equipment concerned against the responsibilities of the safety delegates appointed by him, these responsibilities being limited to decisions within the area of the owner's company or medical practice, as the case may be. Further reformulations refer to the extension of expert knowledge in radiation safety, to the required proof thereof and experience in the requisite field of application, to the supervision and responsibility to be exercised by expert physicians and to the training of medical assistant staff.

[Image quality assurance in x-ray diagnostic units. Information on DIN 6868 standard series]. / Sicherung der Bildqualität in röntgendiagnostischen Betrieben. Informationen zur Normenreihe DIN 6868.

The Working Group for Standardisation justifies and comments on the establishment of a standard series for image quality assurance in X-ray diagnostic services (DIN 6868). In order to promote compliance with these standards, the users are given some background information on the structure of the standard series and on the recommended procedures to be followed. The definitions for the various hierarchically arranged tests, such as constancy test, status test, acceptance test as well as a definition for the term "base-line image quality" are explained.