Patient exposure and image quality of low-dose pulmonary computed tomography angiography: comparison of 100- and 80-kVp protocols

Szucs-Farkas, Zsolt; Kurmann, Luzia; Strautz, Tamara; Patak, Michael A; Vock, Peter; Schindera, Sebastian T (2008). Patient exposure and image quality of low-dose pulmonary computed tomography angiography: comparison of 100- and 80-kVp protocols. Investigative radiology, 43(12), pp. 871-6. Philadelphia, Pa.: Lippincott Williams & Wilkins 10.1097/RLI.0b013e3181875e86

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OBJECTIVE: Measures to reduce radiation exposure and injected iodine mass are becoming more important with the widespread and often repetitive use of pulmonary CT angiography (CTA) in patients with suspected pulmonary embolism. In this retrospective study, we analyzed the capability of 2 low-kilovoltage CTA-protocols to achieve these goals. MATERIALS AND METHODS: Ninety patients weighing less than 100 kg were examined by a pulmonary CTA protocol using either 100 kVp (group A) or 80 kVp (group B). Volume and flow rate of contrast medium were reduced in group B (75 mL at 3 mL/s) compared with group A (100 mL at 4 mL/s). Attenuation was measured in the central and peripheral pulmonary arteries, and the contrast-to-noise ratios (CNR) were calculated. Entrance skin dose was estimated by measuring the surface dose in an ovoid-cylindrical polymethyl methacrylate chest phantom with 2 various dimensions corresponding to the range of chest diameters in our patients. Quantitative image parameters, estimated effective dose, and skin dose in both groups were compared by the t test. Arterial enhancement, noise, and overall quality were independently assessed by 3 radiologists, and results were compared between the groups using nonparametric tests. RESULTS: Mean attenuation in the pulmonary arteries in group B (427.6 +/- 116 HU) was significantly higher than in group A (342.1 +/- 87.7 HU; P < 0.001), whereas CNR showed no difference (group A, 20.6 +/- 7.3 and group B, 22.2 +/- 7.1; P = 0.302). Effective dose was lower by more than 40% with 80 kVp (1.68 +/- 0.23 mSv) compared with 100 kVp (2.87 +/- 0.88 mSv) (P < 0.001). Surface dose was significantly lower at 80 kVp compared with 100 kVp at both phantom dimensions (2.75 vs. 3.22 mGy; P = 0.027 and 2.22 vs. 2.73 mGy; P = 0.005, respectively). Image quality did not differ significantly between the groups (P = 0.151). CONCLUSIONS: Using 80 kVp in pulmonary CTA permits reduced patient exposure by 40% and CM volume by 25% compared with 100 kVp without deterioration of image quality in patients weighing less than 100 kg.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology

UniBE Contributor:

Szücs Farkas, Zsolt; Strautz, Tamara Irmgard; Patak, Michael Andreas; Vock, Peter and Schindera, Sebastian Tobias

ISSN:

0020-9996

ISBN:

19002059

Publisher:

Lippincott Williams & Wilkins

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:04

Last Modified:

04 May 2014 23:20

Publisher DOI:

10.1097/RLI.0b013e3181875e86

PubMed ID:

19002059

Web of Science ID:

000261271300007

URI:

https://boris.unibe.ch/id/eprint/28039 (FactScience: 115910)

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