AN INITIAL REPORT ON THE INVESTIGATION OF HIGH PATIENT DOSES FOR THE LATERAL LUMBOSACRAL PROJECTION IN THE LUMBAR SPINE EXAMINATION

Lumbar spine investigations in our diagnostic imaging department were included in a recent European study of patient dose and image quality. On average, for views other than the lateral projection of the lumbos acral junction, the study found a relatively good image quality at a r easonable average patient dose. For the lumbosacral view the average d ose was high and the spread of doses involved was broader than expecte d. As this is a relatively high dose examination (approx. 40 mGy to sk in) a formal investigation of the methodology involved in this project ion was undertaken. A reject analysis for this projection revealed tha t it was discarded with a high frequency, given the extent to which it is performed and the fact that automatic exposure control (AEC) devic es are commonly used for it. This paper presents results for (a) a sur vey of the pattern of use of AEC and pre-programmed exposure control f acilities by radiographers for the lumbosacral view and (b) the aforem entioned reject analysis of lumbosacral junction and related projectio ns. From the survey of radiographers and related studies, the followin g are identified as possibly being of importance: (i) use of AEC and r elated devices for this view, (ii) the occasions on which such devices are or are not used, and (iii) the reasons why such systems are often not trusted. In the case of the reject analysis, the relatively high reject rate for the projection and the impact and significance of such a rate are highlighted.