Study On The Technical Scheme And Implementation Of CT Stability Test

Objective:To investigate the rationality of the evaluation criteria and the frequency for the specified stability tests,to discuss the stability testing scheme suitable for our hospital’s CT equipments and to provide reference for improving the stability test specification of CT equipments.Methods:According to national standard "Specifications for quality assurance test for computed tomography X-ray scanners" and "Specification for testing of quality control in X-ray computed tomography",5 CT equipments and 1 PET-CT equipment in our hospital were tested for a period of 10 months by using Catphan 600 phantom,water phantom.DCT10 ionization chamber,Barracuda X-ray multifunctional tester,head dose phantom,body dose phantom,etc.The test items included bed positioning accuracy,localization light accuracy,gantry tilt accuracy,reconstruction slice thickness deviation,CTDIw,CT number(water),uniformity,noise,high contrast resolution,low contrast detectability,CT number linearity and image consistency.The characteristics of the test items changing with time were analyzed,the correlations between the test items and equipment level,service life,workload(the total number of cases scanned,exposure dose,exposure time)were discussed,then the reasonable test period and evaluation criteria of the test items were drawn up,finally,the stability test scheme suitable for our hospital’s CT equipments was given,at the same time,the program to improve CT equipment stability test specification is proposed.Results:All the results of the test items of 5 CT equipments and 1 PET-CT equipment meet the evaluation criteria during the 10-month test period except those resulting from accidental measurement errors,subjective measurement errors and untimely maintenance and have no obvious correlation with the equipment level and workload,while the stability of the equipment with longer service life is slightly worse.Conclusion:On the premise of conducting daily start-up and calibration,the results of the stability tests of CT equipments in our hospital meet the requirements of existing testing specifications.Considering the results and clinical application,the modify references about test items,the rationality of the evaluation criteria,the frequency and the test requirement for the stability test of CT equipment are proposed.