RSNA 2008 

Abstract Archives of the RSNA, 2008


SSJ22-05

Influence of Radiation Dose Reduction on Pulmonary Nodule Detection at MDCT without or with Computer-aided Detection

Scientific Papers

Presented on December 2, 2008
Presented as part of SSJ22: Physics (CAD: Methods/Observer Studies)

Participants

Sumiaki Matsumoto MD, PhD, Presenter: Research grant, Toshiba Corporation
Yoshiharu Ohno MD, PhD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Koninklijke Philips Electronics NV Research grant, Bayer AG Research grant, DAIICHI SANKYO Group
Yumiko Onishi MD, Abstract Co-Author: Nothing to Disclose
Hisanobu Koyama MD, Abstract Co-Author: Nothing to Disclose
Daisuke Takenaka MD, Abstract Co-Author: Nothing to Disclose
Hitoshi Yamagata PhD, Abstract Co-Author: Employee, Toshiba Corporation
Kazuro Sugimura MD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Koninklijke Philips Electronics NV Research grant, Mitsubishi Corporation Research grant, Bayer AG Research grant, Eisai Co, Ltd Research grant, DAIICHI SANKYO Group Research Consultant, Shionogi & Co, Ltd
et al, Abstract Co-Author: Nothing to Disclose

PURPOSE

To examine the influence of radiation dose reduction on the performance of chest radiologists in pulmonary nodule detection at MDCT without or with computer-aided detection (CAD).

METHOD AND MATERIALS

Using a prototype CAD system, three chest radiologists (readers 1-3) independently detected non-calcified nodules (≥ 4 mm) in 120 MDCT datasets, with the reading time being recorded. The 120 datasets consisted of standard-dose (150 mAs) datasets (acquired with a 16 or 64 detector-row scanner) of 60 patients and the corresponding 60 low-dose (25 mAs) datasets simulated by adding appropriate Gaussian noise to the raw data of 150 mAs datasets. The readers did the above task in two sessions, reading 60 datasets in each session: firstly without CAD (using the system but unaided) and then 4-6 weeks later with CAD as second reader. The 60 datasets for each session were selected by randomly assigning the 150 mAs and 25 mAs datasets of each patient respectively to the 1st and 2nd sessions or to the 2nd and 1st sessions. The sensitivity and false positive rate (number of false-positive nodules per dataset) of each reader without/with CAD were computed based on the gold standard consisting of 122 nodules (later determined by another chest radiologist). The sensitivity, false positive rate, and reading time of each reader without/with CAD for 150 mAs datasets were statistically compared with those for 25 mAs datasets.

RESULTS

The performance (sensitivity, false positive rate, reading time) without CAD for 150 mAs datasets and that for 25 mAs datasets showed no significant difference for reader 1 (150 mAs: 75%, 0.53, 110 s; 25 mAs: 76%, 0.47, 109 s), reader 2 (150 mAs: 80%, 1.08, 80 s; 25 mAs: 80%, 1.05, 77 s), or reader 3 (150 mAs: 74%, 0.20, 93 s; 25 mAs: 70%, 0.25, 88 s). The performance with CAD for 150 mAs datasets and that for 25 mAs datasets again showed no significant difference for reader 1 (150 mAs: 85%, 0.66, 174 s; 25 mAs: 83%, 0.58, 177 s), reader 2 (150 mAs: 93%, 1.37, 132 s; 25 mAs: 88%, 1.30, 127 s), or reader 3 (150 mAs: 83%, 0.32, 166 s; 25 mAs: 79%, 0.34, 158 s).

CONCLUSION

Almost 83% radiation dose reduction did not significantly influence the performance of chest radiologists in pulmonary nodule detection at MDCT without or with CAD.

CLINICAL RELEVANCE/APPLICATION

Radiation dose of 16 or 64 detector-row CT may be reduced by almost 83% without hampering pulmonary nodule detection by chest radiologists without or with CAD.

Cite This Abstract

Matsumoto, S, Ohno, Y, Onishi, Y, Koyama, H, Takenaka, D, Yamagata, H, Sugimura, K, et al, , Influence of Radiation Dose Reduction on Pulmonary Nodule Detection at MDCT without or with Computer-aided Detection.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6008049.html