As demand for CT consistently rises with global standards for healthcare, it follows along that recent technology and future innovations look to improve upon the current efficiency in scans. This entails better imaging techniques as well as potentially lowering the required dosage of X-rays in each scan to improve safety.

 

Imaging Resolutions

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The temporal resolution for CT is limited by the speed at which the gantry can rotate. For current commercial CT scanners, the minimum time for a half-revolution spin is ~160ms [1]. Should the gantry spin much faster, due to the weight of the object, engineering problems arise in that the large dynamic forces acting on it would require improvements in the design of the machine. An alternative to faster rotation speeds to get higher temporal resolution is to use a second X-ray source/detector – this is called dual source CT (DSCT). DSCT makes it such that the temporal resolution is double that of an equivalent single-sourced helical CT [2][3].

 

Lower Radiation Dosage

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A technique called automated organ-based current modulation is in development where it can reduce the tube current in the x-ray source for certain projections such that direct exposure to sensitive organs eg. the eyes are limited [4]. This way, the projections of these radio-sensitive organs would be produced mainly from indirect angles where the X-rays have already been attenuated to a degree by other tissues and is less needlessly harmful. For example, this technique can be used in cranial CT scans where the eyes do not need to be imaged; accordingly the tube will limit its current such that there is less incident radiation on the eyes directly.

As well as physically lowering dosage, developments in lowering radiation also include further reducing noise in iterative reconstruction techniques [5]; for example, a model-based iterative reconstruction has been tested against ASIR (adaptive statistical iterative reconstruction) in the hopes of achieving lower required radiation doses for similar image quality [6].

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References:

[1] Flohr T.G. et al. (2006). “First performance evaluation of a dual-source CT (DSCT) system” European Radiology vol. 16 no. 2, 256-268.

[2] Flohr TG, et al. (2008). “Image reconstruction and image quality evaluation for a dual source CT scanner”. Medical Physics; vol. 35 no. 12, 5882– 97.

[3] Petersilka M., Bruder H., Krauss B., Stierstorfer K., Flohr T.G. (2008). "Technical principles of dual source CT", Eur. Radiology; vol. 68 no. 3, 362– 8.

[4] Hoang J.K., Yoshizumi T.T., Choudhury K.R., et al. (2012). "Organ-based dose current modulation and thyroid shields: techniques of radiation dose reduction for neck CT", AJR, vol. 198, 1132–8.

[5] Ibrahim M. et al. (2014). “Raise the Bar and Lower the Dose: Current and Future Strategies for Radiation Dose Reduction in Head and Neck Imaging”, AJNR, vol. 34 no. 4, 619-24.

[6] Katsura M, et al. (2012). “Model-based iterative reconstruction technique for radiation dose reduction in chest CT: comparison with the adaptive statistical iterative reconstruction technique.” Eur. Radiology, vol. 22:1613–23