High resolution computed tomography (CT) has become an essential imaging tool for diagnosis and treatment planning of temporal bone diseases [1-3].
Reduction of radiation dose to as-low-as-diagnostically acceptable (ALADA) levels is challenging especially in children, which may need pre- and postoperative images or repeat images in case of recurrent disease.
CT of the temporal bone demands high-resolution images of subtle anatomical bone structures of the middle and inner ear. The purpose of this study was to evaluate limitations of the diagnostic image quality using low...
Description of activity and work performed
Two formalin fixed human cadaver heads were scanned using a reference dose protocol RP (120kV, 300mA, CTDIvol 83.72mGy) and two low-dose protocols LD-1(100kV, 80mA, CTDIvol 26.79 mGy) and LD-2 (100kV, 35mA, CTDIvol 7.66 mGy).
The test images were reconstructed using filtered back projection, and the adaptive statistical iterative reconstructions ASIR 50 and ASIR 100.
Subtle temporal bone structures were assessed individually using a 5-point scale for each protocol:
1 – non visible
2 – nearly visible
3 – visible
4 – well visible
Conclusion and recommendations
RP/LD-1/LD-2 received the following median scores (see Fig 1 and 2):
tendon of the m. tensor tympani (4.0/3.0/2.5)
tendon of the m. stapedius (2.0/1.5/1.0)
incudostapedial joint (4.0/3.5/3.0)
incudomalleolar joint (5.0/4.0/3.5)
stapes feet (3.0/2.5/1.5)
stapes head (4.0/3.0/2.5)
tympanic membrane (4.0/3.0/2.5)
lamina spiralis ossea (2.0/2.0/2.0)
chorda tympani (3.0/3.0/2.0)
Adaptive statistical iterative reconstructions did not provide advantages over filtered back projection. Low-dose protocols may show most anatomical structures and should be selected whenever clinical acceptable.
G. Widmann; Innsbruck/AT - nothing to disclose G. Degenhart; Innsbruck/AT - nothing to disclose L. Jennetten; Innsbruck/AT - nothing to disclose B. Kofler; Innsbruck/AT - nothing to disclose N. Fischer; Innsbruck/AT - nothing to disclose R. Hörmann; Innsbruck/AT - nothing to disclose M. Steurer; Innsbruck/AT - nothing to disclose W. Jaschke; Innsbruck/AT - nothing to disclose
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