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Diagnostic and interventional radiology: a strategy to introduce reference dose level taking into account the national practice

The purpose of this study is to present a strategy to define the reference dose levels for fluoroscopic, dose-intensive examinations. This work is a part of the project of the Federal Office of Public Health of Switzerland to translate the guidelines of the International Commission on Radiological Protection and the European Union into action. The study will also be used to set reference dose levels on the basis of a national survey. All the fluoroscopic units, involved in the survey, were equipped with a KAP (kerma-area product) meter. All KAP meters were first calibrated to ensure the comparability of the dose measurements. The doses and the dose rates together with subjective image quality measurements were acquired in all the centres. Eight types of examination were chosen by a panel of radiologists, and each of the five centres involved agreed to monitor 20 patients per examination type. A wide variation in the dose and the image quality in fixed geometry was observed. For example, the skin dose rate for abdominal examinations varied in the range of 12-42 mGy min−1 for comparable image quality. Average KAP values of 67, 178, 106, 102, 473, 205, 307 and 316 Gy cm2 were recorded for barium meal, abdominal angiography, cerebral angiography, barium enema, hepatic embolisation, biliary drainage, cerebral embolisation and femoral stenting, respectively. The values obtained in this limited study are generally higher than the ones available in the literature and strategies to optimise these studies have to be discussed. A strict control concerning the denomination of the examination type involved in such a study is mandatory to obtain reliable data. This can only be done through a close collaboration between physicians, radiographers and medical physicist

Degeneration of the cervical disc: histology compared with radiography and magnetic resonance imaging

Decisions about the treatment of neck pain are largely made on the basis of information gained from plain X-rays and magnetic resonance imaging (MRI), which are used routinely as part of preliminary investigation. We performed a descriptive cadaveric study to compare histology with radiography and MRI. We correlated plain radiography, disc height [Farfan index (FI)] and MRI findings with histology to assess the ability of radiology to detect significant pathologic lesions. The study included 52 motion segments from nine subjects over the age of 50, who underwent routine hospital autopsy. Disc degeneration was assessed by histology, radiography, disc height (FI: anterior disc height plus posterior disc height divided by anterioposterior diameter) and MRI using established grading systems. Most of the discs were classified radiologically as grade 1 (19/52), grade 2 (13/52), grade 3 (9/52) or grade 4 (3/52). Eight of the discs were graded as normal. The distribution of MRI grades was grade 0 (9/36), grade 1 (9/36), grade 2 (7/36), grade 3 (8/36) and grade 4 (3/36). Half of the discs (26/52) showed advanced (grade 4) degeneration histologically. FI correlated with histological grade (P=0.013), MRI grade (P=0.02) and radiological grade (P<0.001) of degeneration. Radiological and histological grade of degeneration showed a weak correlation (r=0.3, P=0.033). MRI correlated with overall histological grade (r=0.41, P=0.015, n=34). Histological features (e.g., tears, rim lesions, prolapse of nucleus material) were poorly recognised by MRI, which had a sensitivity for disc material prolapse and annulus tears of less than 40%. Our study showed that discs from patients over 50years are histologically severely degenerated; however, these changes may not be detected by conventional radiography and MR

Postmortem imaging of blood and its characteristics using MSCT and MRI

The rapid development of computed tomography (CT) and magnetic resonance imaging (MRI) led to the introduction and establishment in postmortem investigations. The objectives of this preliminary study were to describe the imaging appearances of the early postmortem changes of blood after cessation of the circulation, such as sedimentation, postmortem clotting, and internal livores, and to give a few first suggestions on how to differentiate them from other forensic findings. In the Virtopsy project, 95 human corpses underwent postmortem imaging by CT and MRI prior to traditional autopsy and therefore 44 cases have been investigated in this study. Postmortem alterations as well as the forensic relevant findings of the blood, such as internal or subcutaneous bleedings, are presented on the basis of their imaging appearances in multislice CT and MR

Strategien zur Reduktion der CT-Strahlendosis

Zusammenfassung: Die rasante technische Weiterentwicklung der CT hat in den letzten Jahren zu einer deutlichen Zunahme der diagnostischen Möglichkeiten geführt, mit dem Resultat, dass die CT-Untersuchungszahlen weltweit angestiegen sind. Dies hat ebenfalls Auswirkung auf die Strahlenexposition der Bevölkerung. Bis heute sind zahlreiche Publikationen erschienen, die gezeigt haben, dass eine Dosisreduktion erreicht werden kann, ohne dadurch die Bildqualität und Sensitivität der CT zu beeinträchtigen. Die Mehrzahl der Strategien zur Dosisoptimierung sind einfach anzuwenden und unabhängig von der Detektorkonfiguration des CT-Scanners. Im vorliegenden Übersichtsartikel werden die wichtigsten Methoden vorgestellt: indikationsabhängige Methoden (z.B. rechtfertigende Indikation, Reduktion der Röhrenspannung für die CT-Angiographie, Wahl von Kollimation und Pitchfaktor, Minimierung der Untersuchungsphasen, Senkung der Röhrenspannung und des -stroms für die Nativphase), herstellerabhängige Methoden (z.B. automatische Röhrenstrommodulation, adaptive Filter zur Reduktion des Bildrauschens, iterative Bildrekonstruktion) und allgemeine Methoden (z.B. Patientenzentrierung im Isozentrum der CT-Gantry, Reduktion der Scanlänge, Anwendung von Röntgenschutzmitteln, Reduktion der Röhrenspannung und/oder des -stroms für den CT-Planungsscan