| 1 | Size-specific dose estimates: Localizer or transverse abdominal computed tomography images?显示文摘AIM: To investigate effect of body dimensions obtained from localizer radiograph and transverse abdominal computed tomography(CT) images on Size Specific Dose Estimate. METHODS: This study was approved by Institutional Review Board and was compliant with Health Insurance Portability and Accountability Act. Fifty patients with abdominal CT examinations(58 ± 13 years, Male: Female 28:22) were included in this study. Anteriorposterior(AP) and lateral(Lat) diameters were measured at 5 cm intervals from the CT exam localizer radiograph(simple X-ray image acquired for planning the CT exam before starting the scan) and transverse CT images. Average of measured AP and Lat diameters, as well as maximum, minimum and mid location AP and Lat were measured on both image sets. In addition, off centering of patients from the gantry iso-center was calculated from the localizers. Conversion factors from American Association of Physicists in Medicine(AAPM) report 204 were obtained for AP, Lat, AP + Lat, and effective diameter(√ AP * Lat) to determine size specificdose estimate(SSDE) from the CT dose index volume(CTDIvol) recorded from the dose reports. Data were analyzed using SPSS v19. RESULTS: Total number of 5376 measurements was done. In some patients entire body circumference was not covered on either projection radiograph or transverse CT images; hence accurate measurement of AP and Lat diameters was not possible in 11%(278/2488) of locations. Forty one patients were off-centered with mean of 1.9 ± 1.8 cm(range: 0.4-7 cm). Conversion factors for attained diameters were not listed on AAPM look-up tables in 3%(80/2488) of measurements. SSDE values were significantly different compared to CTDIvol, ranging from 32% lower to 74% greater than CTDIvol. CONCLUSION: There is underestimation and overestimation of dose comparing SSDE values to CTDIvol. Localizer radiographs are associated with overestimation of patient size and therefore underestimation of SSDE. | Sarvenaz Pourjabbar Sarabjeet Singh Atul Padole Akshay Saini Michael A Blake Mannudeep K Kalra | 2014 | World Journal of Radiology2014，6，5： | 1 |
| 5 | Assessment of sub-milli-sievert abdominal computed tomography with iterative reconstruction techniques of different vendors显示文摘AIM: To assess diagnostic image quality of reduced dose(RD) abdominal computed tomography(CT) with 9 iterative reconstruction techniques(IRTs) from 4 different vendors to the standard of care(SD) CT.METHODS: In an Institutional Review Board approved study, 66 patients(mean age 60 ± 13 years, 44 men, and 22 women) undergoing routine abdomen CT on multi-detector CT(MDCT) scanners from vendors A, B, and C(≥ 64 row CT scanners)(22 patients each) gave written informed consent for acquisition of an additional RD CT series. Sinogram data of RD CT was reconstructed with two vendor-specific and a vendor-neutral IRTs(A-1, A-2, A-3; B-1, B-2, B-3; and C-1, C-2, C-3) and SD CT series with filtered back projection. Subjective image evaluation was performed by two radiologists for each SD and RD CT series blinded and independently. All RD CT series(198) were assessed first followed by SD CT series(66). Objective image noise was measured for SD and RD CT series. Data were analyzed by Wilcoxon signed rank, kappa, and analysis of variance tests.RESULTS: There were 13/50, 18/57 and 9/40 missed lesions(size 2-7 mm) on RD CT for vendor A, B, and C, respectively. Missed lesions includes liver cysts, kidney cysts and stone, gall stone, fatty liver, and pancreatitis. There were also 5, 4, and 4 pseudo lesions(size 2-3 mm) on RD CT for vendor A, B, and C, respectively. Lesions conspicuity was sufficient for clinical diagnostic performance for 6/24(RD-A-1), 10/24(RD-A-2), and 7/24(RD-A-3) lesions for vendor A; 5/26(RD-B-1), 6/26(RD-B-2), and 7/26(RD-B-3) lesions for vendor B; and 4/20(RD-C-1) 6/20(RD-C-2), and 10/20(RD-C-3) lesions for vendor C(P = 0.9). Mean objective image noise in liver was significantly lower for RD A-1 compared to both RD A-2 and RD A-3 images(P < 0.001). Similarly, mean objective image noise lower for RD B-2(compared to RD B-1, RD B-3) and RD C-3(compared to RD C-1 and C-2)(P = 0.016).CONCLUSION: Regardless of IRTs and MDCT vendors, abdominal CT acquired at mean CT dose index volume 1.3 m Gy is not sufficient to retain clinical diagnostic performance. | Atul Padole Nisha Sainani Diego Lira Ranish Deedar Ali Khawaja Sarvenaz Pourjabbar Roberto Lo Gullo Alexi Otrakji Mannudeep K Kalra | 2016 | World Journal of Radiology2016，8，6： | 1 |
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