Significant Difference In Effective Dose Research Articles

OPTIMIZATION OF LUNG CT PROTOCOL FOR THE DIAGNOSTIC EVALUATION OF COVID-19 LUNG DISEASE.

This study intends to evaluate the different lung CT scan protocols used for the diagnostic evaluation of COVID-19-induced lung disease in Iranian imaging centers in terms of radiation dose and image quality. After data collecting, subjective image quality, radiation dose and objective image quality such as noise, SNR and CNR were assessed.Statistically significant differences in effective dose and image quality were evident among different lung CT protocols. Lowest and highest effective dose was1.31 ± 0.53 mSv related to a protocol with activated AEC (reference mAs = 20) and 6.15 ± 0.57 mSv related to a protocol with Fixed mAs (mAs = 100), respectively.A protocol with enabled tube current modulation with 70 mAs as a reference mAs, and protocol with 20 mAs and enabled AEC had the best and lowest image quality, respectively. To optimize the scan parameters, AEC must be used, and a range of tube currents (between 20 and 50 mAs) can produce acceptable images in terms of diagnostic quality and radiation dose for the diagnosis of COVID-19-induced lung disease.

Feasibility study of contrast injection scheme based on body mass and iodine flow rate in coronary computed tomography angiography with wide detector CT

Objective: To investigate the feasibility of coronary computed tomography angiography (CCTA) with the individualized contrast medium injection scheme based on body mass and iodine flow rate by using wide detector CT at 100 kV. Methods: From May 2018 to July 2018,270 patients with clinically suspected coronary artery disease underwent CCTA in TEDA International Cardiovascular Hospital. They were randomly divided into three groups, 90 cases in each group: group A was 0.5 ml/kg, group B was 0.6 ml/kg, the flow rate of contrast medium injection in group A and group B was (body mass×25 mg)/the concentration of contrast medium,group C was 0.8 ml/kg and the flow rate of contrast medium was 5 ml/s. Iohexol (iodine concentration 350 mgI/ml) was used in all three groups. The CT values of the aorta root in the three groups, the CT value of the middle segment of LAD and RCA, SNR、CNR、SD of the aortic root, subjective score of coronary artery and effective dose (ED) were compared. Results: There was no significant difference in CT value of aortic root, CT value of middle LAD and RCA, SNR、CNR、SD of the aortic root, subjective score of coronary artery among group A, group B and group C (all P>0.05). The flow rates of the three groups of contrast agents were statistically different (4.5±0.5 vs 4.5±0.5 vs 5, P=0.015), and there was no statistical difference between group A and group B (P>0.05) but lower than group C (P=0.015); the amount of contrast agent in the three groups was statistically different (32±3 vs 38±4 vs 53±7, P<0.001), group A<B Group<C group; there was no significant difference in ED between the three groups (1.5±0.5 vs 1.5±0.6 vs 1.3±0.6, P=0.613). Conclusions: CCTA imaging with a wide body detector based on a 0.5 ml/kg contrast agent dosage and a flow rate of ((body mass × 25)/350) ml/s individualized injection scheme can ensure the image quality while reducing the total amount of contrast agent and realizing individualized iodine flow rate.

Antidiabetic effects of SGLT2 inhibitor ipragliflozin in type 2 diabetic mice fed diets containing different carbohydrate contents

AimsDaily intake of carbohydrates differs among individual patients with type 2 diabetes. Here, we investigated whether or not dietary carbohydrate content affects the efficacy of the sodium-glucose cotransporter 2 (SGLT2) inhibitor ipragliflozin in type 2 diabetic mice. Main methodsDiabetic mice were fed a regular (50% kcal), high (75% kcal)-, or low (25% kcal)-carbohydrate diet. Ipragliflozin was orally administered once a day for 4 weeks. Key findingsIn all groups, mice exhibited characteristics of type 2 diabetes, including hyperglycemia, hyperinsulinemia, and obesity. Hyperglycemia was more severe in the high-carbohydrate diet group and milder in the low-carbohydrate diet group than in the regular diet group. In all diabetic mice, ipragliflozin significantly increased urinary glucose excretion and improved hyperglycemia, hyperinsulinemia, glucose tolerance, insulin resistance, obesity, and nephropathy. Although these antidiabetic effects of ipragliflozin were more marked in the high-carbohydrate diet group (which showed more severe hyperglycemia) than in the other two groups, no significant differences in effective dose or degree of response were observed among the three groups. SignificanceThe antidiabetic effects of ipragliflozin were not greatly affected by dietary carbohydrate content, suggesting that ipragliflozin may have similar efficacy for patients with type 2 diabetes regardless of carbohydrate intake.

A retrospective comparison of intraoperative CT and fluoroscopy evaluating radiation exposure in posterior spinal fusions for scoliosis

BackgroundRadiation exposure is a concern in the field of medicine. Deformity spine surgeons depend on modalities that have high exposure through scoliosis x-rays or computed tomography. The use of fluoroscopy has increased with the increased use of pedicle screws. Recently other 3-D imaging devices with navigation have also been brought onto the market to improve accuracy of screw placement. There is concern that because of the use of CT, the radiation dose to the patient is increased, however there is little literature that directly compares the amount of radiation using the 3-D devices to traditional fluoroscopy. Although we know intraoperative CT decreases the amount of radiation to the surgeon and operating room staff, there is limited comparison data for exposure to patients. Our study focused on a comparison of radiation exposure data for pediatric scoliosis patients receiving posterior spinal fusions using traditional fluoroscopy and the Medtronic O-arm in an effort to determine the method most likely to decrease radiation exposure in the pediatric population.MethodsRetrospective review of data in patient charts from two pediatric surgeons practicing in both a University and private hospital setting. Data collected included age, weight, height, diagnosis, Cobb angle, fusion levels, number of screws, and number of hooks, O-arm spins, fluoro doses and O-arm doses. Effective dose was calculated using output measures and radiation doses were compared along a continuum that took into account the amount of correction as indicated by Cobb angle.ResultsA total of 57 patients, 25 using the O-arm and 32 using traditional fluoroscopy, were analyzed. Effective dose was calculated and then compared as a factor correlated to curve severity. At lower angles of correction we found no statistically significant difference between methods in terms of effective radiation dose. There was no statistically significant divergence until a Cobb angle correction of greater than 74 degrees, where the Oarm dose was shown to be lower by comparison.ConclusionWe found that regardless of the methods used there is still a significant radiation dose that is utilized in scoliosis procedures. The two methods analyzed did not display statistically significant differences in effective dose for the average case. Safely managing radiation exposure for pediatric patients is of the utmost priority. Healthcare professionals, however, face repeated exposure to radiation over the course of a long career. In our data set the O-Arm system does not increase overall exposure for patients and decreases radiation doses for providers and thereby provides a safe alternative to traditional fluoroscopy without compromising accuracy of implant placement or patient care.Level of Evidence: III.

Comparison of spectral imaging and conventional CT in CT angiography of the kidney: image quality and radiation dose

Objective To compare the image quality and radiation dose of CTA of the kidney in patients using routine CT and the spectral imaging combination of different scanning protocols with the adaptive statistical iterative reconstruction 2.0 algorithm (ASIR 2.0). Methods A total of 90 patients who had undergone a CTA of the kidney were divided into three groups (A, B and C), with 30 patients in each group. Group A underwent a routine CT examination, and the scan parameters are:120 kVp, 30 to 650 mA, rotation time 0.5 s/r, scan FOV 50 cm×50 cm; while groups B and C underwent spectral imaging protocol 1 and 2, the scan parameters of spectral imaging protocol 1 and 2 are: rapid dual kVp (80-140 kVp) switching in 0.25 ms, 375 mA and 360 mA, rotation time 0.7 s/r and 0.6 s/r, scan FOV 36 cm×36 cm and 32 cm×32 cm, respectively. All images were reconstructured using ASIR 2.0. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated when the kidney CTA was completed. Each subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists. The CT dose index (CTDIvol) and dose-length product (DLP) were recorded, and the mean value was calculated. The DLP was converted to the effective dose (ED). All data were compared with Kruskal-Wallis test and one-way ANOVA. Results The energy level of 49 to 56 keV was found to provide the best CNR for displaying CTA of the kidney. There were significant differences in CT values, noise, SNR, CNR and subjective score between groups B, C and A (P 0.05). There were significant differences in ED among groups A, B and C (P<0.05), and the ED of groups A, B and C were (8.2±1.2), (5.2±0.9) and (4.4±0.7) mSv, respectively. Conclusion Spectral imaging with different scanning protocols can more effectively reduce the radiation dose than the routine CT scan mode for a kidney CTA while still maintaining diagnostic image quality, and protocol 2 of spectral imaging in our study is recommended. Key words: Renal Artery; Angiography; Tomography, X-ray computed; Radiation dosage

Determination of size specific conversion factors to effective dose using tld dosimeters in anthropomorphic phantoms

Introduction This study refers to effective dose (ED) estimation using the size-specific dose estimator (SSDE). Purpose This work aims at determining DLP SSDE -to-ED (k SSDE ) conversion factors where DLP SSDE is the length product multiplied by the appropriate f-factor (AAPM report 204) for chest-abdomen-pelvis (CAP) CT examinations in three weight-adjusted scan protocols and to compare the ED SSDE derived from k SSDE to that derived from k factors available in the literature. Materials and methods Three anthropomorphic phantoms of 55 kg, 73.5 kg and 96.2 kg body weight filled with 190 TLDs were scanned on a 64-slice multi-detector CT employing the respective weight-adjusted CAP-CT protocol used in clinical routine. Effective diameter was measured in the abdomen area of the phantoms and DLP SSDE was estimated using the respective f factor. For ED estimation, ICRP 103 tissue weighting factors for all organs inside and outside the irradiation field were used. Relevant k SSDE conversion factors were then calculated. These factors were then applied to 140 patients underwent CAP-CT examinations and the derived ED SSDE values were compared to corresponding ED k values. Results In the SSDE was 15.4% higher than ED k while in the medium category (60–90 kg) the corresponding percentage was 28.3%. For the over-weighted category (>90 kg) no significant difference in ED was observed. Conclusion Weight-adjusted DLP SSDE -to-ED conversion factors were determined. In low and medium weight categories, radiation dose may be underestimated when the patient size is not taken into consideration.

Cone-Beam CT with Fluoroscopic Overlay Versus Conventional CT Guidance for Percutaneous Abdominopelvic Abscess Drain Placement

PurposeTo compare technical success and procedure time for percutaneous abscess drain placement with fluoroscopic cone-beam computed tomography (CT) and two-axis needle guidance versus conventional CT guidance. Materials and MethodsA total of 85 consecutive patients undergoing abdominopelvic abscess drain placement guided by fluoroscopic cone-beam CT or conventional CT were retrospectively reviewed over a 2-year period. Forty-three patients underwent drain placement with cone-beam CT using XperGuide navigation and 42 underwent placement with conventional 64-slice CT. Patient characteristics, median abscess size (6.8 cm vs 7.8 cm; P = .14), and depth to abscess (7.2 cm vs 7.7 cm; P = .88) were similar between groups. ResultsTechnical success rates were 98% (42 of 43) in the cone-beam CT group and 100% (42 of 42) in the conventional CT group (P = .32), with a 10-F pigtail drainage catheter inserted in the majority of cases. There were no complications in either group. There was no significant difference in effective dose between groups (9.6 mSv vs 10.7 mSv; P = .30). Procedure times were significantly shorter in the cone-beam CT group (43 min vs 62 min; P = .02). In addition, during the study period, there was a gradual improvement in procedure time in the cone-beam CT group (50% reduction), whereas procedure time did not change for the conventional CT group. ConclusionsCone-beam CT guidance appears to be equivalent to conventional CT guidance for drain placement into medium-sized abdominopelvic collections, yielding similar technical success rates and radiation doses, with the additional benefit of reduced procedure times.

Patient dose estimation in cardiac computed tomography with a 320 detector row scanner based on Monte Carlo simulation

Patient dose estimation in cardiac computed tomography with a 320 detector row scanner based on Monte Carlo simulation

Low-dose abdominal CT: Comparison of low tube voltage with moderate-level iterative reconstruction and standard tube voltage, low tube current with high-level iterative reconstruction

To evaluate the quality of 100 kVp images with a hybrid iterative reconstruction algorithm level of 40% and 120 kVp (low-tube-current) images with a hybrid iterative reconstruction algorithm level of 60% in low-dose abdominal computed tomography (CT) using almost the same radiation dose. This prospective study received institutional review board approval and written informed consent was obtained. One hundred and ten patients undergoing abdominal dynamic CT were randomly assigned to one of two protocols (100 and 120 kVp protocols). Radiation doses of the two protocols were almost identical. The 120 kVp images were post-processed with a hybrid iterative reconstruction algorithm level of 60% (i-120 kVp). The 100 kVp images were post-processed with a hybrid iterative reconstruction algorithm level of 40% (i-100 kVp). The effective dose (ED), image noise, CT attenuation, and signal-to-noise ratio (SNR) of the subcutaneous fat, muscle, liver, pancreas, and kidneys were compared between the protocols using Student's t-test. Qualitative analysis was also performed between the protocols. There were no significant differences in ED and SNR of any of the regions of interest (ROIs) between the protocols (p > 0.05). However, in the qualitative analysis, unnatural texture was significantly greater in the i-120 kVp than in the i-100 kVp protocol (p < 0.01). There were no other significant differences in the image quality between the protocols (p > 0.05). The combined use of low tube voltage and moderate-level iterative reconstruction techniques can be a more effective strategy for reducing patient radiation dose while attaining acceptable image quality than the use of standard tube voltage, low tube current with high-level iterative reconstruction.

Intravenous contrast medium administration at 128 multidetector row CT pulmonary angiography: Bolus tracking versus test bolus and the implications for diagnostic quality and effective dose

To investigate the effects of a test bolus protocol contrast medium administration on diagnostic image quality in computed tomography pulmonary angiography (CTPA). Fifty patients referred for exclusion of pulmonary embolism underwent CTPA using a test bolus protocol CTPA at 120 kVp and were compared with 50 patients undergoing CTPA using a standard bolus-tracking protocol at 120 kVp, via assessment of attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) seen in the pulmonary arteries (PAs). An additional group of 10 non-obese patients who underwent CTPA using a test bolus protocol performed at 100 kVp were also analysed. Mean effective dose was calculated from the dose-length product, using standard conversion factors. The test bolus protocol showed significantly higher attenuation, SNR, and CNR in the pulmonary vasculature down to the segmental level compared to bolus-tracking CTPA (p < 0.0001). There was no significant difference in effective dose between the test bolus and bolus tracking cohorts. The additional group of test bolus CTPA examinations performed at 100 kVp had a significantly reduced effective dose in comparison to both test bolus CTPA at 120 kVp and bolus-tracking CTPA at 120 kVp (p < 0.005) yet maintained mean PA attenuation to segmental level significantly better than bolus-tracking CTPA performed at 120 kVp and comparable to the test bolus cohort performed at 120 kVp. Test bolus contrast administration should be used as an optimal protocol. Performing test bolus CTPA at 100 kVp, as opposed to 120 kVp, significantly reduces dose without compromising PA attenuation in non-obese subjects.

Comparison of Radiation Doses From Multislice Computed Tomography Coronary Angiography and Conventional Diagnostic Angiography

The aim of this study was to quantify and compare effective doses from conventional angiography and multislice computed tomography (MSCT) coronary angiography using a 16-slice scanner. Multislice computed tomography is now a viable modality for cardiac imaging. However, for any diagnostic use of ionizing radiation, the risk to the patient must be considered and justified. Multislice computed tomography angiography and conventional angiography were used to assess 180 patients with suspected coronary artery disease. Estimates of effective dose were derived from exposure data recorded for each patient examination. For each modality, a comparable calculation technique was used, based on Monte Carlo modeling of the standard Cristy phantom. In a subset of 91 directly comparable patients the mean effective dose for MSCT coronary angiography was 14.7 mSv (SD 2.2) and that for conventional angiography was 5.6 mSv (SD 3.6). A significant difference in effective dose was seen between the two protocols. The mean effective dose for MSCT coronary angiography was significantly higher than that for conventional angiography. As MSCT cardiac scanners become increasingly available, operators must be aware of the radiation dose and the factors that affect it.

Comparison of Effective Doses for Low-Dose MDCT and Radiographic Examination of Sinuses in Children

Our objective was to show that in low-dose MDCT of the sinuses in children the effective dose can be lowered to a level comparable to that used for standard radiographic images, with resultant CT scans that are still of diagnostic image quality. In standard radiographic examinations of sinuses (anteroposterior and lateral views) with 75 kV, 20 mAs, and 3-mm aluminum filtration in 69 children (mean age, 4.2 years), the dose-area-product (DAP; mGy x cm2) was measured and converted to effective dose (mSv) according to coefficients published by the British National Radiological Protection Board. Another group of 125 children (mean age, 6.8 years) underwent low-dose MDCT of the sinuses with 6- or 16-MDCT in two phases and with different scanning protocols. An effective dose for MDCT was calculated from conversion of the dose-length-product (DLP, mGy xm) according to age. The mean effective dose (E) for standard radiography was 0.0528 mSv. The mean E value for low-dose MDCT was 0.096 mSv in the first phase of the study but could be lowered in the second phase to 0.0531 mSv by a combination of higher pitch and faster scan rotation time in our scan protocols, which results in diagnostic image quality at a very low dose. Statistical analysis showed no significant differences in effective dose between radiography and MDCT of the second phase. With modern MDCT technology, low-dose CT of the sinuses in children can yield diagnostic image quality using an effective dose comparable to that used for standard radiography.

Quality criteria implementation for brain and lumbar spine CT examinations.

A study was undertaken to implement the quality criteria proposed by the European Commission for brain general and lumbar spine (disc herniation) CT examinations. The proposed criteria were evaluated for samples including 93 brain and 86 lumbar spine CT examinations, with special emphasis on the diagnostic and radiation dose requirements. The extent to which the image criteria had been achieved was evaluated after two independent observers had each read the images twice. Dose measurements were conducted in parallel to estimate the proposed dose quantities needed to obtain the images. For brain examinations, we found that a group of image criteria were largely met, and met uniformly in all sites. One criterion (1.2.5) was frequently fulfilled but had intermediate values for two sites; the remaining criteria were fulfilled to different extents, although for criteria 1.2.1 and 1.2.2, scores were lower than 50% and 70%, respectively. The mean percentage image quality score had values between 57% and 78%, with variation coefficients in the range 30-68%. Mean values of the dose quantities were in the ranges 44-74 mGy for weighted CT dose index (CTDIw), 497-1018 mGy cm for dose-length product (DLP) and 1.1-2.2 mSv for effective dose (E). CTDIw and DLP were not correlated because of significant variations in the scanned length, whereas DLP and E were strongly correlated. A weak relationship between image quality score and DLP was found for the sample as a whole. For lumbar spine examinations, none of the critical reproduction image criteria was systematically achieved. One group of criteria (1.2.7, 1.2.8 and 1.2.9) was fulfilled to a large extent in many departments, but fulfilment of the remainder varied widely. The mean score fluctuated in the range 39-88%, with three groups of differences: low (39-51%), intermediate (67-71%) and high (85-88%). Mean values of the CTDIw varied between sites in the range 27-48 mGy. Mean DLP values varied between 188 mGy cm and 333 mGy cm, and the mean effective dose ranged between 3 mSv and 5 mSv. There were significant differences in effective dose between men and women. By sites, there was no relationship between DLP and mean score, with the highest image score associated with intermediate dose values. The percentage disagreement among the observers about a given criterion ranged between 2% and 22% for brain, and between 3% and 46% for lumbar spine.