ABSTRACT
The aim of this study was to evaluate the suitability of size specific dose estimates (SSDE) to estimate patient dose in Fast kVp switching dual energy CT. An anthropomorphic phantom (RAN-110) was repeatedly scanned (chest, abdomen and the pelvis) using a 64 detector row MDCT (Discovery CT750 HD, GE Healthcare, Milwaukee, WI, USA) with various CT parameters, including Fast kVp switching. Dosimetry was performed using thermo-luminescent dosimeters, positioned both superficially and within the phantom. SSDE was calculated for all slices of the anthropomorphic phantom using both the localiser and axial images. In Fast kVp switching, SSDE underestimated the measured absorbed dose for the chest/abdomen region ~35% at the maximum, but were in closer agreement for the pelvic region about within 10%. In single energy techniques, SSDE could not be applied in the estimation of organ doses, but in Fast kVp switching dual energy techniques, SSDE could be applied for anatomical regions with larger thicknesses.
Subject(s)
Abdomen/radiation effects , Pelvis/radiation effects , Phantoms, Imaging , Radiation Monitoring , Radiography, Dual-Energy Scanned Projection/methods , Tomography, X-Ray Computed/methods , Humans , Radiation Dosage , Radiography, ThoracicABSTRACT
AIM: To compare contrast enhancement and image quality between renovascular computed tomography (CT) images with adaptive statistical iterative reconstruction (ASiR) and that with model-based iterative reconstruction (MBIR). MATERIAL AND METHODS: This retrospective study was approved by the institutional review board and written informed consent was waived. Twenty-five consecutive patients who underwent renovascular CT were enrolled in this study. The same raw projection data were reconstructed using ASiR 40%, 100%, and MBIR. Background noise, CT attenuation, and signal-to-noise ratio (SNR) of the renal vessels and kidneys, and image quality were compared among the three reconstruction techniques. RESULTS: Mean background noise was significantly lower with MBIR at the first and second phases than those with ASiR 40% and 100% (p<0.0001). Mean CT attenuation of the abdominal aorta, renal artery, and renal cortex obtained at the first phase and those of the renal vein and renal medulla at the second phase were comparable among the three techniques (p=0.051-1.00). Mean SNRs of the abdominal aorta, renal artery, renal cortex, renal vein, and renal medulla were significantly higher with MBIR than with ASiR 40% or 100% (both p<0.0001). The depiction of the renal artery and vein as well as image quality significantly improved with MBIR compared with those with ASiR 40% and 100% (p<0.0001-0.0016). CONCLUSION: Reconstruction of renovascular CT images with MBIR significantly reduces background noise, leading to an improvement in SNR and image quality compared with that using ASiR.
Subject(s)
Image Processing, Computer-Assisted/methods , Kidney/blood supply , Kidney/diagnostic imaging , Radiographic Image Enhancement/methods , Radiographic Image Interpretation, Computer-Assisted/methods , Tomography, X-Ray Computed/methods , Adult , Aged , Aged, 80 and over , Aorta, Abdominal/diagnostic imaging , Female , Humans , Kidney Medulla/diagnostic imaging , Male , Middle Aged , Renal Artery/diagnostic imaging , Renal Veins/diagnostic imaging , Reproducibility of Results , Retrospective Studies , Signal-To-Noise RatioABSTRACT
A new ultrasonic equipment for ophthalmological diagnosis has been developed. Manual compound scanning using water immersion made acurate representation of cross-section of the orbital structure possible. A large, focused transducer brought resolution and sensitivity. Gray scale display of the ultrasonogram increased information concerning intensity of echoes. Ultrasonograms of retinoblastoma, vitreous hemorrhage, melanocytoma, optic disc coloboma and unilateral exophthalmos are presented.
