| Zugriffsnummer | 34601 |
| Dokumenttyp | Zeitschriftenartikel |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | Metrological aspects of dosimetry in X-ray diagnostics |
| Autor(in); Institution |
Büermann, Ludwig; 6.2, Dosimetrie für Strahlentherapie und Röntgendiagnostik, PTB-Braunschweig
|
| Quelle/Jahr | Ionizing radiation in medicine. PTB-Mitteilungen: 123 (2013), 2, Spec. Issue, 8 - 15 |
| ISSN | NO-ISSN |
| Verlag | Braunschweig: Physikal.-Techn. Bundesanstalt |
| Freie Schlagworte | X-ray diagnostics ; application-specific dose quantities ; quality control ; diagnostic reference levels ; patient dosimetry |
| Zusammenfassung | Almost half of the radiation the German population is exposed to and which is caused by ionizing radiation from natural and artificial sources originates from X-ray examinations. Dosimetry in X-ray diagnostics is, therefore, of particular importance. The purpose of dosimetry in X-ray diagnostics is, on the one hand, to ensure quality control according to the state of the art of science and technology and, on the other hand, patient dosimetry to estimate the risks arising from radiation exposure. The fundamental quantity of dosimetry is the air kerma, which is primarily measured with the aid of free-air ionization chambers. From the air kerma, the application-specific dose quantities are derived, for example, the incident dose and the dose area product for projection radiography, and the dose length product for computed tomography. These establish the basis for dose measurements within the scope of quality assurance by means of acceptance inspections and constancy tests and for the determination of diagnostic reference levels. The latter serve as upper standard values which must, on average, not be exceeded in the examination of humans. However, also the organ-absorbed dose and the tissue-absorbed dose of standard patients are determined from the application-specific dose quantities with the aid of calculated conversion factors. The effective patient doses calculated from these are used for risk assessments in comparison with radiation exposures from other sources of ionizing radiation. According to a recommendation of the ICRU, dosimetry in X-ray diagnostics should, for the purposes mentioned, be carried out with an expanded uncertainty (k=2) of not more than approx. 7 %. Even if the uncertainties of the primary and secondary standards already seem to be sufficiently small (approx. 0.6 % and 1.5 %), this specification has, by far, not yet been implemented in clinical practice, where uncertainties of up to 25 % are still found. Original German version published in: PTB-Mitteilungen 123 (2013), No. 2 |
