scholarly journals Assessment of the Radiation Dose during 16 Slices CT Examinations

2019 ◽  
Vol 8 (4) ◽  
pp. 4652-4657
Keyword(s):  
Experimental Study ◽  
Monte Carlo ◽  
Radiation Dose ◽  
Effective Dose ◽  
Clinical Applications ◽  
Clinical Protocols ◽  
Dose Length Product ◽  
Conversion Factors ◽  
Current Tube ◽  
Tube Current

In this work. Two studies were presented. The first one is an experimental study of the influence of different scan parameters (potential tube. current tube and pitch) on the radiation dose is presented. It has been demonstrated that the radiation dose increases if we increase the tube current or the potential current. Contrary to the pitch. the radiation dose is reduced when the pitch increases. The second study is a Monte Carlo validation of a CT named SOMATION emotion from Siemens using GATE. Results were carried out for different voltage 80.110.130 kVp. Results of the simulation are presented and good agreements are observed (less than 2.6% for head phantom. and less than 4.6% for body phantom for all applied voltages). The influence of changing the phantom diameter on the CTDIw was also presented. the CTDIw decreased nonlinearly with increasing the phantom diameter. Moreover. the CTDIw differences decreased if the phantom diameter increased. It was demonstrated that the CTDI100 values can be characterized as functions of the kVp. mAs and diameter of phantoms. Based on these results. it is possible to optimize the CT parameters in clinical applications. Finally the effective dose was calculated using the method dose length product and the conversion factors for four clinical protocols.

ESTIMATION OF RADIATION DOSE IN CT VENOGRAPHY OF THE LOWER EXTREMITIES: PHANTOM EXPERIMENTS USING DIFFERENT AUTOMATIC EXPOSURE CONTROL SETTINGS AND SCAN RANGES

2019 ◽  
Vol 188 (1) ◽  
pp. 109-116
Author(s):  
Yusuke Inoue ◽  
Hiroyasu Itoh ◽  
Kazunori Nagahara ◽  
Yuka Takahashi
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Lower Extremities ◽  
Whole Body ◽  
Exposure Control ◽  
Automatic Exposure Control ◽  
Dose Length Product ◽  
Ct Venography ◽  
Tube Current ◽  
Phantom Experiments

Abstract We performed phantom experiments to assess radiation dose in computed tomography (CT) venography of the lower extremities. CT images of a whole-body phantom were acquired using different automatic exposure control settings and scan ranges, simulating CT venography. Tube current decreased in the lower extremities compared to the trunk. The scout direction and dose modulation strength affected tube current, dose length product (DLP) and effective dose. The middle and distal portions of the lower extremities contributed substantially to DLP but not to effective dose. When effective dose was estimated by multiplying DLP by a single conversion factor, overestimation was evident; this became more pronounced as the scan range narrowed. In CT venography of the lower extremities, the scout direction and modulation strength affect radiation dose. Use of DLP severely overestimates radiation dose and underestimates effects of scan range narrowing.

scholarly journals Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise

2014 ◽  
Vol 4 ◽  
pp. 38 ◽  
Author(s):  
Lukas Ebner ◽  
Felix Knobloch ◽  
Adrian Huber ◽  
Julia Landau ◽  
Daniel Ott ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Radiation Dose ◽  
Dose Reduction ◽  
Integrated Circuit ◽  
Chest Ct ◽  
Back Projection ◽  
Dose Length Product ◽  
Chest Computed Tomography ◽  
Tube Current

Objective: The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT) by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP) and an iterative reconstruction (IR) algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany) was investigated. Materials and Methods: 136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP), SOMATOM Definition Flash (IR), and SOMATOM Definition Edge (ICD and IR). Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product. Results: Dose-length product (DLP) with FBP for the average chest CT was 308 mGy*cm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGy*cm ± 68.8 (P = 0.0001). Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGy*cm ± 54.5 (P = 0.033). The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR) was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048). Overall contrast-to-noise ratio (CNR) improved with declining DLP. Conclusion: The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations.

scholarly journals Variation in tube voltage for pediatric neck 64VCT: Effect on radiation dose and image quality

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259772
Author(s):  
Li-Guo Chen ◽  
Ping-An Wu ◽  
Hsing-Yang Tu ◽  
Ming-Huei Sheu ◽  
Li-Chuan Huang
Keyword(s):  
Image Quality ◽  
Radiation Dose ◽  
Region Of Interest ◽  
Ct Scanner ◽  
Multidetector Row Ct ◽  
Dose Length Product ◽  
Multidetector Row ◽  
Tube Current ◽  
Noise Measurements ◽  
Unpaired Student

Exposure to ionizing radiation can cause cancer, especially in children. In computed tomography (CT), a trade-off exists between the radiation dose and image quality. Few studies have investigated the effect of dose reduction on image quality in pediatric neck CT. We aimed to assess the effect of peak kilovoltage on the radiation dose and image quality in pediatric neck multidetector-row CT. Measurements were made using three phantoms representative of children aged 1, 5, and 10 years, with tube voltages of 80, 100, and 120 kilovoltage peak (kVp); tube current of 10, 40, 80, 120, 150, 200, and 250 mA; and exposure time = 0.5 s (pitch, 0.984:1). Radiation dose estimates were derived from the dose-length product with a 64-multidetector-row CT scanner. Images obtained from the control protocol (120 kVp) were compared with the 80- and 100-kVp protocols. The effective dose (ED) was determined for each protocol and compared with the 120-kVp protocol. Quantitative analysis entailed noise measurements by recording the standard deviation of attenuation for a circular 1-cm2 region of interest placed on homogeneous soft tissue structures in the phantom. The mean noise of the various kVp protocols was compared using the unpaired Student t-test. Reduction of ED was 37.58% and 68.58% for neck CT with 100 kVp and 80 kVp, respectively. The image noise level increased with the decrease in peak kilovoltage. Noise values were higher at 80 kVp at all neck levels, but did not increase at 100 kVp, compared to 120 kVp in the three phantoms. The measured noise difference was the greatest at 80 kVp (absolute increases<2.5 HU). The subjective image quality did not differ among the protocols. Thus, reducing voltage from 120 to 80 kVp for neck CT may achieve ED reduction of 68.58%, without compromising image quality.

Optimization of computed tomography urography protocol, 1997 to 2008: Effects on radiation dose

2009 ◽  
Vol 50 (4) ◽  
pp. 446-454 ◽  
Author(s):  
P. Dahlman ◽  
L. Jangland ◽  
M. Segelsjö ◽  
A. Magnusson
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Effective Dose ◽  
Excretory Urography ◽  
Ct Urography ◽  
Tube Current Modulation ◽  
Current Modulation ◽  
Tube Current ◽  
The Mean ◽  
The Impact

Background: Since computed tomography (CT) urography began to replace excretory urography as the primary imaging technique in uroradiology, the collective radiation dose to the patients has increased. Purpose: To examine the changes in the CT urography protocol for investigating suspected urinary tract malignancy between the years 1997 and 2008, and how these changes have influenced the mean effective dose. Material and Methods: The study was based on 102 patients (mean age 66.1±14.8 years, range 31–89 years; 30 female, 72 male) divided into five groups (groups A–E) corresponding to the time points at which changes were made to the CT urography protocol. The mean effective doses were estimated using the ImPACT CT Patient Dosimetry Calculator. Results: The number of scan phases at CT urography was reduced from four to three in 1999, resulting in a reduction of the mean effective dose from 29.9/22.5 (female [F]/male [M]) mSv (group A) to 26.1/18.9 (F/M) mSv (group B). In 2001, mAs settings were adapted to patient size, and the mean effective dose was reduced to 16.8/12.0 (F/M) mSv (group C). In 2005, scans were performed with a multidetector-row CT equipped with automatic tube current modulation in the x- and y-axis (CARE Dose). The effective mAs was also lowered in the unenhanced and excretory phase, yet the mean effective dose increased to 18.2/13.1 (F/M) mSv (group D), since the effective mAs had to be increased in the corticomedullary phase to maintain image quality. In 2008, as tube current modulation in the x-, y-, and z-axis was introduced (CARE Dose4D), the mean effective dose was reduced to 11.7/8.8 (F/M) mSv (group E). Conclusion: This study shows that the individual mean effective dose to patients undergoing CT urography has decreased by 60%, from 29.9/22.5 (F/M) mSv in 1997 to 11.7/8.8 (F/M) mSv in 2008.

Radiation dose from 3D rotational X-ray imaging: organ and effective dose with conversion factors

2011 ◽  
Vol 150 (1) ◽  
pp. 50-54 ◽  
Author(s):  
S. Kim ◽  
D. Sopko ◽  
G. Toncheva ◽  
D. Enterline ◽  
B. Keijzers ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Conversion Factors ◽  
X Ray ◽  
X Ray Imaging
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