AN INVESTIGATION INTO CT RADIATION DOSE VARIATIONS FOR HEAD EXAMINATIONS ON MATCHED EQUIPMENT.

This study investigated radiation dose and image quality differences for computed tomography (CT) head examinations across centres with matched CT equipment. Radiation dose records and imaging protocols currently employed across three European university teaching hospitals were collated, compared and coded as Centres A, B and C from specification matched CT equipment models. Patient scans (n = 40) obtained from Centres A and C were evaluated for image quality, based on the visualisation of Commission of European Community (CEC) image quality criteria using visual grading characteristic (VGC) analysis, where American Board of Radiology examiners (n = 11) stated their confidence in identifying anatomical criteria. Mean doses in terms of CT dose index (CTDIvol-mGy) and dose length product (DLP-mGy cm) were as follows: Centre A-33.12 mGy and 461.45 mGy cm; Centre B -101 mGy (base)/32 mGy (cerebrum) and 762 mGy cm and Centre C-71.98 mGy and 1047.26 mGy cm, showing a significant difference (p ≤ 0.05) in DLP across centres. VGC analysis indicated better visualisation of CEC criteria on Centre C images (VGCAUC 0.225). All three imaging protocols are routinely used clinically, and image quality is acceptable in each centre. Clinical centres with identical model CT scanners have variously customised their protocols achieving a range of dose savings and still resulting in clinically acceptable image quality.

Responsiveness of the one-leg hop test and the square hop test to fatiguing intermittent aerobic work and subsequent recovery.

The purpose of the present study was to evaluate the responsiveness of the 1-leg hop test and the square hop (SH) test to fatiguing intermittent aerobic work and during recovery. A further aim was to study sex differences in trends. Members of 4 sub-elite-level soccer teams were invited to participate. Ten men (mean ± SD) aged 20.7 ± 3.4 years and 10 women aged 21.8 ± 4.8 years accepted to participate in the test. The Yo-Yo intermittent Endurance test Level 2, was used as a standardized sport-specific fatiguing protocol. The 1-leg hop test and the SH test were performed before, immediately after, 15, and 30 minutes after the fatiguing exercise. To quantify the level and progression of fatigue and recovery, blood lactate and heart rate were measured, and general fatigue was estimated on Borg's rating of perceived exertion scale. No significant difference in performance in either of the hop tests was found immediately after intermittent aerobic fatiguing work. Performance in the 1-leg hop test significantly decreased (p = 0.002), whereas that in the SH test increased (p = 0.001) between baseline and 15-30 minutes after fatiguing work. No significant difference in trends between sexes was found. The performance in the 1-leg hop test significantly decreased during 30 minutes of recovery compared with that in the nonfatigued conditions and might therefore be used on the field as a complement to other physical parameters to detect remaining fatigue. Note that the 1-leg hop test did not immediately respond to intermittent aerobic work. It is not recommended to use the SH test for measuring fatigue and subsequent recovery because the performance constantly increased despite the present objective and subjective fatigue.