Impact of active dose management on radiation exposure and image quality in computed tomography: An observational study in 1315 patients

Determining optimal imaging protocols for enhanced chest CT: From phantom to clinical study

OBJECTIVES

To investigate the optimal imaging protocols for enhanced chest CT to achieve good image quality and diagnostic performance with a lower radiation dose.

MATERIALS AND METHODS

This IRB-approved study included both phantoms and patients. Two phantoms were scanned using 4 scanning modes. Images in each group were reconstructed using adaptive statistical iterative reconstruction-V (ASiR-V) at three strength levels of 40%, 60%, and 80%, denoted A1-3-D1-3, respectively with 1-3 representing the three ASiR-V levels. The image quality and radiation dose were evaluated to obtain the best imaging mode. 48 patients underwent contrast-enhanced standard dose CT (SDCT, protocol A) and low-dose CT (LDCT, protocol D) of the chest for follow-up. The image quality, radiation dose, and volume measurements of the left lung, right lung, and trachea using an AI-based software were compared.

RESULTS

In the phantom study, D2 protocol which had the lowest dose, was selected as the optimal imaging protocol for enhanced chest CT. Compared with SDCT, LDCT reduced the radiation dose by 45% compared to SDCT. Images in LDCT with ASiR-V60% had similar noise as the standard SDCT images with the standard ASiR-V40%, but they had higher SNRs and CNRs. In addition, the volumes of the left lung, right lung, and bronchus did not significantly differ between the two groups.

CONCLUSION

The combination of Auto-kV prescription and ODMfull with ASiR-V60% in contrast-enhanced chest CT can achieve individualized low dose scanning with satisfactory image quality and diagnostic accuracy.

Evaluating the impact of dose monitoring software alerts on radiation dose reduction in computed tomography: A systematic review

INTRODUCTION

Radiation Dose Monitoring Software (DMS) tools have been developed to monitor doses and alert computed tomography (CT) users of high radiation exposure. However, the causal factors for alerts and the impact of DMS in dose optimisation are poorly understood.

AIM

This review aims to identify high-dose CT examinations triggering alerts and their determinants, and to assess if the alerts from DMS help to reduce CT dose levels.

METHODS

To identify relevant articles published to December 2023, an electronic search of Medline, Scopus, CINAHL, Embase, and the Web of Science was undertaken. Reference lists of published articles were also assessed to identify further articles. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was employed to evaluate articles for relevance. Articles were included if they used the DMS tool to detect high-dose events that issued alerts in CT and were published in English.

RESULTS

The search resulted in 83 articles, of which, nine were included after a thorough screening process. High dose alerts most often occurred in CT chest, CT head/brain, CT Chest/abdomen/pelvis, and CT abdomen/pelvis with alert percentages ranging from 1.45% to 10.21%, 1.54% to 4.18%, 4.48% to 6.60%, and 4.47% respectively. Alerts were mainly triggered by overweight patients, scan repetition, miscentering of the patients, extra CT study added, orthopaedic hardware in the scanning area and scanning beyond the desire anatomy. Most of the studies reviewed show that DMS tools played a role in reducing the number of high-dose events that trigger alerts.

CONCLUSION

DMS tools are valuable in automatically identifying high-dose CT protocols, enabling quick investigation and dose optimisation. The high-dose events occurred due to patient and technical factors, which can be mitigated through proper monitoring and investment in both technological resources and staff training.

[Restructuring Torso CT Protocol for Radiation Dose Management]

PURPOSE

There are problems with dose management in X-ray computed tomography (CT) because the protocol used for any examination is not always in the same scan range. The purpose of this study was to investigate the usefulness of setting the CT protocol based on the scan range.

METHODS

We evaluated the examination data of patients who underwent plain CT based on a scan range of chest to pelvis and abdomen to pelvis. The previous protocol [Chest-Abdomen Routine] was changed to the current protocols [Chest_Abdomen] and [Chest_Pelvis], and the previous protocol of [Abdomen Routine] was changed to the current protocols [Abdomen] and [Abdomen_Pelvis]. Examination data of height, scan length, volume CT dose index (CTDI_vol), and dose length product (DLP) were obtained from digital imaging and communications in medicine, and radiation dose structured report using Radimetrics. The relationship between patient height and scan range, and CTDI_vol and DLP was indicated in a scatter plot. Standard deviation (SD) of scan length and DLP were compared between current and previous protocols. Outliers were defined as the data exceeding average ±2SD.

RESULTS

The SD of scan length decreased by 77.1% on abdomen to pelvis, and the SD of DLP decreased by 65.2% on abdomen to pelvis. The causes of the outliers were CT scan range, scan parameter, arm position, metal implants, and body thickness of patients.

CONCLUSION

Setting CT protocols based on the scan range reduced SD of scan length and DLP. It was helpful for reducing the number of scan range outliers and analyzing the cause of outliers.

CT dose management of adult patients with unknown body weight using an effective diameter

PURPOSE

To assess the usefulness of effective diameter (D_eff) for CT dose management of adult patients with unknown body weight.

METHODS

A total of 642 adult patients whose height and weight had been measured before CT examination (chest CT using Aquilion Prime SP, 428 patients; chest CT using Biograph mCT, 100 patients; and abdominal CT using Aquilion Prime SP, 114 patients) were retrospectively examined between April 2018 and September 2019. The D_eff was automatically calculated from the lateral diameter on a CT localizer radiograph by a dose management software (Radimetrics). In order to determine the correlation between body weight and D_eff, we compared volume CT dose index and dose length product between patients with body weight between 50 and 70 kg and those with D_eff equivalent to body weight between 50 and 70 kg. Correlation analysis was performed by Pearson's product-moment correlation, and statistical analyses were performed by using t-test.

RESULTS

The correlation coefficient values between body weight and D_eff were 0.920 for chest CT using Aquilion Prime SP, 0.929 for chest CT using Biograph mCT, and 0.805 for abdominal CT using Aquilion Prime SP. In both chest and abdominal CT scans, there were no significant differences in volume CT dose index and dose length product between patients with body weight between 50 and 70 kg and those with D_eff equivalent to body weight between 50 and 70 kg.

CONCLUSIONS

The D_eff may be useful as a somatometric parameter for CT dose management of adult patients with unknown body weight.