A Phantom-based Investigation Into the Influence of Low Tube Potential and Matrix Size on Radiation Dose and Image Quality for a 128 Slice Abdominopelvic Ct Protocol
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Abstract
Introduction: Reducing radiation dose for CT examinations has been accompanied by an increase in image noise. Studies have highlighted the application of a higher matrix size for improving image quality when assessing the lungs. This study aims to evaluate the influence of a low kVp and higher matrix size on radiation dose and image quality for abdominopelvic CT. Methods: This experiment was done on a 32 cm body phantom and scanned using a 128 slice CT scanner. The study utilised various combinations of kVp settings (140, 120, 100, 80 & 70) and matrix sizes (1024, 768 & 512). The image obtained was analysed objectively and subjectively. For objective analysis, we calculated SNR, and CNR. For subjective analysis, two radiologists evaluated the image in a 3-point scoring scale. Results: The study reported an increase in SNR (0.8%) and CNR (46%) at 120 kVp when increasing the matrix size from 512 x 512 to 768 x 768. Similarly, there was an increase of 14.5 % and 56.4 % in CNR and SNR using 1024 matrix size. The DLP was reduced by 4.5%, 50% and 70.6 % using 100, 80 and 70 kVp respectively. However, there was no change in DLP with higher matrix sizes. Conclusion: The study reported a combination of 100 kVp and 768 matrix size resulted in an almost similar (↓0.9 %) SNR and improved CNR (↑46.4 %) compared to 120 kVp and 512 matrix size. Qualitative analysis also showed a similar image quality with decreased radiation dose for abdominopelvic CT.
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1. Brenner DJ, Hall EJ. Current concepts - Computed tomography - An increasing source of radiation exposure. New England Journal of Medicine. 2007; 357:2277-2284.
Sulieman A, Adam H, Elnour A, Tamam A, Alhaili A, et al. Patient radiation dose reduction using a commercial iterative reconstruction technique package. Radiation Physics and chemistry. 2021; 178:108996; 1-7
Almohiy H. Paediatric computed tomography radiation dose: A review of the global dilemma. World Journal of Radiology. 2014; 6(1):1-6.
Booij R, Budde R, Dijkshoorn M, Straten M. Technological developments of x-ray computed tomography over half a century: user’s influence on protocol optimization. European journal of radiology.2020;131(109261):1-11
Guite KM, Hinshaw JL, Ranallo FN, Lindstrom MJ, Lee FT Jr. Ionizing radiation in abdominal CT: unindicated multiphase scans are an important source of medically unnecessary exposure. J Am Coll Radiol. 2011 Nov;8(11):756-61
Kayyum A, Panakkal N C, John A M. Evaluation of effective dose and associated radiation risks in common computed tomography procedures. Indian journal of public health research and development. 2020;11(3): 460-465
Brix G, Nissen-Meyer S, Lechel U, Nissen-Meyer J, Griebel J, Nekolla EA, et al. Radiation exposures of cancer patients from medical X-rays: how relevant are they for individual patients and population exposure? Eur J Radiol. 2009 Nov;72(2):342-7
Yamashita, K, Higashino, K, Hayashi H, Takegami, K, Hayashi, F, et al. Direct measurement of radiation exposure dose to individual organs during diagnostic computed tomography examination. Sci Rep 11, 5435 2021. [doi: 10.1038/s41598-021-85060-5]
Van der Molen AJ, Joemai RM, Geleijns J. Performance of longitudinal and volumetric tube current modulation in a 64-slice CT with different choices of acquisition and reconstruction parameters. Phys Med. 2012 Oct;28(4):319-26
Solomon J.B, Li X, Samei E, Relating Noise to image quality indicators in CTexaminations with tube current modulation. AJR Am. J. Roentgenol.2013; 200(3):592–600.
Wang J, Fleishcmann D. Improving spatial resolution at CT: Development ,benefits and pitfalls. Radiology.2018; 289 (1): 261-262.
Hata A, Yanagawa M, Honda O, Kikuchi N, Miyata T, Tsukagoshi S, et al. Effect of Matrix Size on the Image Quality of Ultra-high-resolution CT of the Lung: Comparison of 512 × 512, 1024 × 1024, and 2048 x 2048. Acad Radiol. 2018 Jul;25(7):869-876
Chang, K.-P, Hsu T.-K, Lin W.-T.,Hsu, W.-L. Optimisation of dose and image quality in adult and pediatric computed tomography scans. Radiation Physics and Chemistry. 2017 140, 260–265.
Rosner B. Fundamentals of Biostatistics.7th edition. Boston: Brooks/Cole,Cengage Learning;2011
Sabarudin A, Mustafa Z, Nassir KM, Hamid HA, Sun Z. Radiation dose reduction in thoracic and abdomen-pelvic CT using tube current modulation: a phantom study. J Appl Clin Med Phys. 2014 Jan 8;16(1):5135.
Papadakis AE, Perisinakis K, Damilakis J. Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality. Eur Radiol. 2014 Oct;24(10):2520-31
Zhu H, Zhang L, Wang Y, Hamal P, You X, Mao H, et al. Improved image quality and diagnostic potential using ultra-high-resolution computed tomography of the lung with small scan FOV: A prospective study. PLoS One. 2017 Feb 23;12(2):e0172688
Kristen B. Aquilon Precision ultra-high resolution CT: Quantifying diagnostic image quality.2018.[https://global.medical.canon/publication/ct/2018WP_Aquilion_Precision_Ultra-High_Resolution]
Yanagawa M, Gyobu T, Leung AN, Kawai M, Kawata Y, Sumikawa H, et al. Ultra-low-dose CT of the lung: effect of iterative reconstruction techniques on image quality. Acad Radiol. 2014 Jun;21(6):695-703.
Pichardt PJ, Lubner MG, David H, Jie T, Julie A, Alejandro M, et al . Abdominal CT with model iterative reconstruction (MBIR):intial results of prospective trial comparing ultra-low dose with standard dose imaging.AJR Am J Roentgenol 2012;199:1266-1274.
Godoy MC, Samantha L, David P, Bernard A, Christianne L, et al. Duel energy MDCT: Comparison of pulmonary artery enhancement on dedicated pulmonary angiography, routine and low contrast volume studies. Eur J Radiol.2011 79(2); E11-E17.
Nicole E, Adam L. An evaluation of the effect of tube potential on clinical image quality using direct digital detector for pelvis and lumbar spine radiographs. J med Radiat sci. 2020;67: 260-268.
Charnley C, England A, Martin A, Taylor S, Benson N,Jones L. An option for optimising the radiographic technique for horizontal beam lateral (HBL) hip radiography when using digital X-ray equipment.Radiography 2016; 22(2): e137–e142
Lorusso JR, Fitzgeorge L, Lorusso D, Lorusso E. Examining practitioners’ assessments of perceived aestheticand diagnostic quality and high kVp-Low mAs pelvis,chest, skull, and hand phantom radiographs. J MedImaging Radiat Sci 2015; 46(2): 162–73
Barba J, Culp M. Copper Filtration and kVp: Effect on entrance skin exposure. Radiol Technol 2015;46(2):162-73