An evaluation of SAFIRE’s potential to reduce the dose received by paediatric patients undergoing CT: a narrative review

Introduction: The purpose of this review is to gather and analyse current research publications to evaluate Sinogram-Affirmed Iterative Reconstruction (SAFIRE). The aim of this review is to investigate whether this algorithm is capable of reducing the dose delivered during CT imaging while maintaining image quality. Recent research shows that children have a greater risk per unit dose due to increased radiosensitivity and longer life expectancies, which means it is particularly important to reduce the radiation dose received by children. Discussion: Recent publications suggest that SAFIRE is capable of reducing image noise in CT images, thereby enabling the potential to reduce dose. Some publications suggest a decrease in dose, by up to 64% compared to filtered back projection, can be accomplished without a change in image quality. However, literature suggests that using a higher SAFIRE strength may alter the image texture, creating an overly ‘smoothed’ image that lacks contrast. Some literature reports SAFIRE gives decreased low contrast detectability as well as spatial resolution. Publications tend to agree that SAFIRE strength three is optimal for an acceptable level of visual image quality, but more research is required. The importance of creating a balance between dose reduction and image quality is stressed. In this literature review most of the publications were completed using adults or phantoms, and a distinct lack of literature for paediatric patients is noted. Conclusion: It is necessary to find an optimal way to balance dose reduction and image quality. More research relating to SAFIRE and paediatric patients is required to fully investigate dose reduction potential in this population, for a range of different SAFIRE strengths. I N T R O D U C T I O N Computed tomography (CT) is valuable for diagnostic insight. However, X-ray images taken during CT examinations expose the patient to a high dose of radiation, which has the potential to cause cancer. Recent US cancer risk projections estimate 1 cancer per 1000 brain CT scans for patients under 5 years of age1; it is therefore understandable that radiation dose has been a longstanding concern for paediatric patients, particularly when multiple scans are required. One of the possible solutions for dose reduction is the use of iterative reconstruction instead of conventional filtered back projection (FBP). Sinogram Affirmed Iterative OPTIMAX 2014 – radiation dose and image quality optimisation in medical imaging 10 Reconstruction (SAFIRE), developed by Siemens, is one of the newest available iterative algorithms. Based on its noise reduction capabilities, it is believed that this algorithm may have the potential to significantly reduce dose in children undergoing CT scans without sacrificing image quality. This review attempts discusses whether SAFIRE is suitable for dose reduction in patients undergoing CT. Our focus is to analyse whether dose can be reduced for paediatric patients whilst maintaining an image quality that is acceptable for diagnosis. Literature search and review strategy Literature searching was conducted on several computerised databases (ScienceDirect, PubMed), online journals and publishers were also utilised, such as AJR Online and Springer. As SAFIRE is relatively new, published articles available are limited. English articles from all years of publishing were included in this literature review; dates ranged from 2012 to 2014.