CT Radiation Dose Reduction in Pediatric Cardiovascular Anomalies – Clinical Audit in a Single Centre

Shahjehan Alam; Ummara Siddique Umer; Syed Ghulam Ghaus; Seema Gul; Aman Nawaz Khan; Sadia Gul; Rafiq Ahmed; Shaista Nawaz

CT Radiation Dose Reduction in Pediatric Cardiovascular Anomalies – Clinical Audit in a Single Centre

Shahjehan Alam, Ummara Siddique Umer, Syed Ghulam Ghaus, Seema Gul, Aman Nawaz Khan, Sadia Gul, Rafiq Ahmed, Shaista Nawaz

Abstract

Purpose:
To reduce radiation dose from Multidetector computed tomography (MDCT) using techniques with low tube voltage and modified image parameters without significant degradation of image quality.

AUDIT TARGET:

Radiation dose reduction using 80 kV and 100 kV protocols for MDCT.

Materials and Methods:
This is a prospective analysis with single blind selection of cardiac anomaly patients referred to radiology department of Rehman medical institute Peshawar for cardiac CT scan during Jan 2013 to Dec 2015. Total of 100 patients with age range of 1 week to 16 years were selected with echocardiographic suspicion of cardiovascular anomalies. It was probability sampling. Scan was performed on 128 multislice Toshiba scanner. ECG gated retrospective and prospective scanning was performed using modified tube voltage (80kVp, 100kVp and 120 kVp) and with manual adjustment of low tube current. Radiation dose measurement was done by multiplying conversion factor with dose length product (DLP), which was provided by the CT scanner. Data wa processed using Microsoft Excel 2010. Images were reviewed on 5.1 vitrea workstation using multiplanar and 3D reconstruction. Two radiologists independently assessed subjective quality of the CT images to assess cardiac anomalies and normal anatomical structures.

Results:

Prospective ECG gating significantly reduced the radiation dose 22 mSv (retrospective) to 13.96 mSv (prospective) with standard inbuilt 120kVp setting. Reducing the kVp to 100 further reduced dose to 10.3 mSv and dropped down to 5.46mSv with 80kVp and no significant image distortion. Manually adjusting and reducing the mAs with added filtration reduced the radiation dose to 3.64mSv.

Conclusion:
We conclude from our results that prospective ECG gated cardiac CT, low kVp and mAs values show great potential for substantially reducing radiation dose of cardiac CT angiography. By using different radiation lowering dose techniques i.e. prospective ECG gating technique, low kVp and mAs, we were able to reduce radiation dose by 83.45% (22 to 3.46 mSv)

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References

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