Comparison of CT Pulmonary Angiography Quality at Low Tube Voltage (80 Kvp) With Standard Conditions (100 Kvp) Among the Patients with Suspected Pulmonary Embolism

Mohammad Davoodi, Mohammad Gharibvand, Goodarz Shahrami Babakan


Background: Pulmonary embolism (PE) is a common and potentially devastating cardiovascular complication with a high mortality rate, worldwide. The diagnosis based solely on the presence of clinical features remains challenging due to heterogeneity of the nonspecific manifestations of the disease. CT pulmonary angiography (CTPA) is a fast, accurate and cost effective diagnostic test of PE, as the radiation exposure to the patient is the major disadvantage of this technique. Since voltage drop result in reduce radiation exposure, comparison of image quality at different tube voltages may provide an optimum and secure voltage for patients.

Aim: Comparison of CTPA quality at low tube voltage (80 kVp) with standard conditions (100 kVp) among the patients with suspected pulmonary embolism, referred to the Golestan Hospital, Ahvaz

Materials and methods: In this triple-blind clinical trial, 92 patients with suspected PE already admitted to the Golestan Hospital, randomly divided into two equal groups and CTPA was performed at 2 different dose protocols: group A (80 kVp) and group B (100 kVp). The groups were then compared based on the image quality scores reported by two radiologists, along with the image quality parameters (SNR, and CNR) and the radiation dose (DLP).

Results: The overall image quality score of in-group A was higher than that in-group B (p = 0.002). Although group A was also superior (P < 0.0001) to group B with regard to image noise, but the signal-to-noise ratio (SNR) and the carrier-to-noise ratio (CNR) values were similar at different contrast levels for both groups. In addition, the radiation dose (DLP) was lower in-group A than in-group B.

Conclusion: The results indicated that a reduction in tube voltage from 100 kV to 80 kV in CTPA could both reduce the radiation dose and improve the diagnostic image quality.

Key words: CT pulmonary angiography, Voltage, Image quality, Radiation

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