Determination of optimal CT exposure factors for lung lesions using an anthropomorphic chest phantom for SPECT-CT

Thompson, J; Szczepura, K; Tootell, AK; Sil, J; Manning, D; Hogg, P

Abstract

PURPOSE: SPECT‐CT is a valuable modality for diagnosis and staging of primary and secondary
malignant disease and also diagnosing benign conditions. CT incurs a significant radiation burden;
consequently CT acquisition parameters require optimisation to conform to the ALARP principle.
METHOD: An anthropomorphic chest phantom was scanned on the Toshiba Aquilion 16‐ slice
MDCT at 135kV, 1mmx16 detector configuration (reconstructed at 3mm slices and 3mm
intervals), 320mm FOV with variation of mA (10‐25) and pitch (0.94 and 1.44). Simulated lesions
(5, 8 and 10mm at 100HU) were placed in clinically relevant positions within the phantom. 5
image readers of varying CT experience completed the study; data was analysed via Jackknife
Free‐Response Receiver Operating Characteristic (JAFROC) and Dorfman‐Berbaum‐Metz Multi‐
Reader Multi‐Case (DBM‐MRMC) analysis. Signal to noise ratio (SNR) was also measured for all
simulated lesions. RESULTS: JAFROC method revealed no significant difference between
acquisition options (variation of mA and pitch) or image readers (ANOVA). Image readers with
experience in producing reports on investigations made a greater number of non‐lesion
localisations (NL) (false positives) compared to those who had no reporting responsibility or
experience. Reader performance was generally better at lower pitch protocols for the same mA.
Increased partial voluming could account for this. CONCLUSION: Results suggest equal
performance for acquisition parameters in terms of the localisation information provided. This
suggests no significant deterioration in image quality at lower resolutions. Despite this it is
thought that low pitch (0.94) techniques should be favoured due to general improved reader
performance at this level. No correlation was seen between SNR and JAFROC confidence ratings.
Further study would attempt to investigate an even lower mA range for further dose saving
potential.

Citation

Thompson, J., Szczepura, K., Tootell, A., Sil, J., Manning, D., & Hogg, P. (2010). Determination of optimal CT exposure factors for lung lesions using an anthropomorphic chest phantom for SPECT-CT. European Journal of Nuclear Medicine and Molecular Imaging, 37(Sup. 2), S494. https://doi.org/10.1007/s00259-010-1560-8

• Journal Article Type: Conference Paper
• Conference Name: European Association of Nuclear Medicine (EANM) 2010
• Conference Location: Vienna, Austria
• End Date: Oct 13, 2010
• Publication Date: Sep 7, 2010
• Deposit Date: Feb 26, 2021
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Print ISSN: 1619-7070
• Electronic ISSN: 1619-7089
• Publisher: Springer Verlag
• Volume: 37
• Issue: Sup. 2
• Pages: S494
• DOI: https://doi.org/10.1007/s00259-010-1560-8
• Publisher URL: https://doi.org/10.1007/s00259-010-1560-8
• Related Public URLs: http://link.springer.com/journal/259
• Additional Information: Event Type : Conference