ABSTRACT
Objective To assess and compare the difference in image quality and exposure dose between single-sided reading image plate(IP)and dual-sided reading IP.Methods A contrast-detail phantom CDRAD 2.0 was exposed by single-sided and dual-sided reading IP with different mAs sets.The entrance surface doses were recorded for all images.Images were then presented to two radiologists on a high resolution monitor of diagnosis workstation.The image quality figure(IQF)was measured for each image. Statistical analysis was performed using Spearman's correlation test and Wilcoxon signed-rank test to compare the difference in image quality and exposure dose between single-sided IP and dual-sided reading IP. Results With different tube current dosage of 5.6,12.0,20.0,25.0,and 40.0 mAs,IQF values of single-sided reading IP were 47.95,37.68,34.31,28.61,and 24.65,respectively,while those of dual- sided reading IP were 38.83,29.81,29.65,25.16,and 21.43,respectively.The IQF difference between them showed statistical significance(P
ABSTRACT
Objective To study the rationality and possibility of 64 slice spiral CT in the examination of the temporal bone at low dose.Methods The same CT technique and temporal bone mode as those for clinical CT were used,two cranium specimens(four ears)were scanned with Somatom Sensation 64-slice spiral CT at different mA(380,300,200,160,120,80),and muhi-planar reformation was performed.The CT dose index at different mA groups were measured by 10 cm pencil ionization chamber and head dose phantom.Four anatomic structures on axial images(subarcuate fossa,tendon of tensor tympani, facial recess,etc),four anatomic structures on coronal images(scute,crista transversa,fenestra cochleae, etc)and six anatomic structures on double oblique images(malleus,incus,stirrup bone,upper bony semicircular,etc)were chosen to evaluate and grade the reformation images among different mA groups,and to determine the minimum mA value.Ten ears of five patients were used to test the validity of the minimum mA value.Results CT radiation dose was significantly reduced from(47.8?2.7)to(20.1?2.0)raCy (P