Towards image quality, beam energy and effective dose optimisation in digital thoracic radiography

2001 ◽  
Vol 11 (5) ◽  
pp. 870-875 ◽  
Author(s):  
J. H. Launders ◽  
A. R. Cowen ◽  
R. F. Bury ◽  
P. Hawkridge
Author(s):  
I. Shirazu ◽  
T. A Sackey ◽  
E K Eduful ◽  
T B. Dery ◽  
M. Pokoo-Aikins ◽  
...  

Risk of developing cancer in paediatric patients is higher compared with adults and hence need for optimization strategies in paediatric medical imaging is very critical. The higher risk is attributable to the fact that children have developing organs and tissues which are more sensitive to the effects of radiation, and also they have longer life expectancy which allows more time for any harmful effects of radiation to manifest. Optimization of radiological protection is a means of adjusting imaging parameters and instituting protective measures such that required images are obtained with lowest possible radiation dose, and net benefit is maximized to maintain sufficient image quality for diagnostic purposes. Special consideration is given to the availability of dose reduction measures for paediatric imaging equipment. A unique aspect of paediatric imaging is with regards to the wide range in patient sizes and weights, therefore requiring special attention to optimization and modification of equipment, technique, and imaging parameters. Good radiographic technique for paediatrics include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimization of exposure factors etc. In CT, dose reduction is optimized by the adjustment of scan parameters such as mA, kVp, and pitch in accordance with patient weight, age, region scanned, and study indication. Paediatric radiological imaging should therefore be performed by trained and experienced health personnel in the medical imaging department. The overall aim of the research was to enhance the capability of Ghana to improve the efficiency of existing modalities for paediatric medical imaging and to implement and enhance optimization techniques and methodologies for advanced paediatric medical imaging in CT. In addition to providing appropriate clinical recommendation for clinicians for dose management during CT scan. MVL DICOM application software was used to access image data during abdominal CT scan. Effective dose estimates were estimated as developed by ICRP 103 recommendations. The data collection was based on retrospective extraction of image data, using MVL platform where detailed information of the CTDIvol and DLP were available for recording. The weighted CTDI (CTDIW) was estimated by multiplying the volumetric CTDI (CTDIVOL) by the pitch factor. The effective dose was estimated by the product of the region-specific normalizing constant and the dose length product on each image. For image quality Signal to Noise Ratio was estimated and compare with effective dose for dose optimisation. In conclusion, the mean dose parameters exceeded the recommended dose parameter and hence an urgent need for an action to minimise radiation dose to paediatric patients.


2010 ◽  
Vol 51 (3) ◽  
pp. 260-270 ◽  
Author(s):  
Peter Björkdahl ◽  
Ulf Nyman

Background: Concern has been raised regarding the mounting collective radiation doses from computed tomography (CT), increasing the risk of radiation-induced cancers in exposed populations. Purpose: To compare radiation dose and image quality in a chest phantom and in patients for the diagnosis of pulmonary embolism (PE) at 100 and 120 peak kilovoltage (kVp) using 16-multichannel detector computed tomography (MDCT). Material and Methods: A 20-ml syringe containing 12 mg I/ml was scanned in a chest phantom at 100/120 kVp and 25 milliampere seconds (mAs). Consecutive patients underwent 100 kVp ( n = 50) and 120 kVp ( n = 50) 16-MDCT using a “quality reference” effective mAs of 100, 300 mg I/kg, and a 12-s injection duration. Attenuation (CT number), image noise (1 standard deviation), and contrast-to-noise ratio (CNR; fresh clot = 70 HU) of the contrast medium syringe and pulmonary arteries were evaluated on 3-mm-thick slices. Subjective image quality was assessed. Computed tomography dose index (CTDIvol) and dose–length product (DLP) were presented by the CT software, and effective dose was estimated. Results: Mean values in the chest phantom and patients changed as follows when X-ray tube potential decreased from 120 to 100 kVp: attenuation +23% and +40%, noise +38% and +48%, CNR −6% and 0%, and CTDIvol −38% and −40%, respectively. Mean DLP and effective dose in the patients decreased by 42% and 45%, respectively. Subjective image quality was excellent or adequate in 49/48 patients at 100/120 kVp. No patient with a negative CT had any thromboembolism diagnosed during 3-month follow-up. Conclusion: By reducing X-ray tube potential from 120 to 100 kVp, while keeping all other scanning parameters unchanged, the radiation dose to the patient may be almost halved without deterioration of diagnostic quality, which may be of particular benefit in young individuals.


Dose-Response ◽  
2018 ◽  
Vol 16 (4) ◽  
pp. 155932581880583 ◽  
Author(s):  
Ernesto Forte ◽  
Serena Monti ◽  
Chiara Anna Parente ◽  
Lukas Beyer ◽  
Roberto De Rosa ◽  
...  

Purpose: To compare image quality and radiation dose among different protocols in patients who underwent a 128-slice dual source computed tomography coronary angiography (DSCT-CTCA). Methods: Ninety patients were retrospectively grouped according to heart rate (HR): 26 patients (group A) with stable HR ≤60 bpm were acquired using high pitch spiral mode (FLASH); 48 patients (group B) with irregular HR ≤60 bpm or stable HR between 60 and 70 bpm using step and shoot mode; and 16 patients (group C) with irregular HR >60 bpm or stable HR ≥70 bpm by retrospective electrocardiogram pulsing acquisition. Signal to noise ratio (SNR) and contrast to noise ratio (CNR) were measured for the main vascular structures. Moreover, the dose-length product and the effective dose were assessed. Results: Both SNR and CNR were higher in group A compared to group C (18.27 ± 0.32 vs 11.22 ± 0.50 and 16.75 ± 0.32 vs 10.17 ± 0.50; P = .001). The effective dose was lower in groups A and B (2.09 ± 1.27 mSv and 4.60 ± 2.78 mSv, respectively) compared to group C (9.61 ± 5.95 mSv) P < .0001. Conclusion: The correct selection of a low-dose, HR-matched CTCA scan protocol with a DSCT scanner provides substantial reduction of radiation exposure and better SNR and CNR.


2018 ◽  
Vol 148 ◽  
pp. 112-120
Author(s):  
Donghoon Lee ◽  
Sunghoon Choi ◽  
Haenghwa Lee ◽  
Dohyeon Kim ◽  
Seungyeon Choi ◽  
...  

2017 ◽  
Vol 3 (2) ◽  
pp. 591-594 ◽  
Author(s):  
Anja Stüssi ◽  
Marta Bogowicz ◽  
Verena Weichselbaumer ◽  
Patrick Veit-Haibach ◽  
Oliver Riesterer ◽  
...  

AbstractPerfusion computed tomography (CTP) images tumor angiogenesis and can assess tumor aggressiveness. However, the CTP examinations are dose intensive. This study aimed to optimize a routinely used CTP protocol for the head and neck region in oncology in order to reduce the effective dose to the patient and simultaneously achieve the same image quality.The Alderson phantom was scanned on a GE Revolution CT scanner. A scan with our standard protocol for head and neck cancer patients was used (100kV, 80mAs, 5mm slice thickness and backprojection algorithm) and in seven predefined regions (ROI) the signal to noise ratio (SNR) was measured. For the dose optimized protocol, the tube voltage was lowered and the mAs adaptation protocol was used. To improve image quality different percentage of an adaptive statistical iterative reconstruction (ASiR) was applied. For a better resolution we set the slice thickness to 2.5 mm. The mAs adaption range and the percentage of the ASiR reconstruction were varied until we found a combination with the same median SNR in the seven defined ROIs as for our old protocol. For the old and the optimized protocol dose measurements were performed using 25 LiF-TLDs. Organ doses were calculated and the effective dose was determined based on the weighting factors of ICRP103.The optimized scanning protocol used a voltage of 80kV, a mAs range between 15 and 80, a noise level of 10%, and 50% ASiR reconstruction. The median SNR ratio was slightly better (14% better SNR) with the new protocol. An effective dose of 8 mSv was measured with the original protocol and 4 mSv with the optimized scanning protocol. For organs in the scanning field the dose was reduced by a factor of 2 and outside the field by a factor of 2.2.Advanced reconstruction algorithms allow a significant dose reduction and an improvement of image resolution, while maintaining the image quality.


2014 ◽  
Vol 162 (4) ◽  
pp. 597-604 ◽  
Author(s):  
A. G. Davies ◽  
A. J. Gislason-Lee ◽  
A. R. Cowen ◽  
S. M. Kengyelics ◽  
M. Lupton ◽  
...  

2015 ◽  
Vol 26 (7) ◽  
pp. 2030-2038 ◽  
Author(s):  
Bouchra Habib Geryes ◽  
Raphael Calmon ◽  
Diala Khraiche ◽  
Nathalie Boddaert ◽  
Damien Bonnet ◽  
...  

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