Radiation dose differences between thoracic radiotherapy planning CT and thoracic diagnostic CT scans

Sanderud, A; England, A; Hogg, P; Fosså, K; Svensson, S; Johansen, S

Abstract

Purpose: To compare the absorbed dose from computed tomography (CT) in radiotherapy planning (RP CT) against those from diagnostic CT (DG CT) examinations and to explore the possible reasons for any dose differences.
Method: Two groups of patients underwent CT-scans of the thorax with either DG-CT (n=55) or RP-CT (n=55). Patients from each group had similar weight and body mass index (BMI) and were divided into low (<25) and high BMI (>25). Parameters including CTDIvol, DLP and scan length were compared.
Results: The mean CTDIvol and DLP values from RP-CT (38.1 mGy, 1472 mGy·cm) are approximately four times higher than for DG-CT (9.63 mGy, 376.5 mGy·cm). For low BMI group, the CTDIvol in the RP-CT scans (36.4 mGy) is 6.3 times higher than the one in the DG-CT scans (5.8 mGy). For high BMI group, the CTDIvol in the RP-CT (39.6 mGy) is 2.5 times higher than the one in the DG-CT scans (15.8 mGy). In the DG-CT scans a strong negative linear correlation between noise index (NI) and mean CTDIvol was observed (r =-0.954, p=0.004); the higher NI, the lower CTDIvol. This was not the case in the RP-DG scans.
Conclusion: The absorbed radiation dose is significantly higher and less BMI dependent for RP-CT scans compared to DG-CT. Image quality requirements of the examinations should be researched to ensure that radiation doses are not unnecessarily high.

Citation

Sanderud, A., England, A., Hogg, P., Fosså, K., Svensson, S., & Johansen, S. (2016). Radiation dose differences between thoracic radiotherapy planning CT and thoracic diagnostic CT scans. Radiography, 22(2), 107-111. https://doi.org/10.1016/j.radi.2015.08.003

• Journal Article Type: Article
• Acceptance Date: Aug 18, 2015
• Online Publication Date: Sep 12, 2015
• Publication Date: May 1, 2016
• Deposit Date: Oct 1, 2015
• Publicly Available Date: Sep 18, 2016
• Journal: Radiography
• Print ISSN: 1078-8174
• Electronic ISSN: 1532-2831
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 22
• Issue: 2
• Pages: 107-111
• DOI: https://doi.org/10.1016/j.radi.2015.08.003
• Publisher URL: http://dx.doi.org/10.1016/j.radi.2015.08.003
• Related Public URLs: http://www.journals.elsevier.com/radiography/