Strategies for dose reduction with specific clinical indications during computed tomography

Abstract

Increasing integration of computed tomography (CT) into routine patient care has escalated concerns regarding associated radiation exposure. Specific patient cohorts, particularly those with cystic fibrosis (CF) and Crohn's disease, have repeat exposures and thus have an increased risk of high lifetime cumulative effective dose exposures.Thoracic CT is the gold standard imaging method in the diagnosis, assessment and management of pulmonary disease. In the setting of CF, CT demonstrates increased sensitivity compared with pulmonary function tests and chest radiography. Furthermore, in specific cases of Crohn's disease, CT demonstrates diagnostic superiority over magnetic resonance imaging (MRI) for radiological evaluation.Low dose CT protocols have proven beneficial in the evaluation of CF, Crohn's disease and renal calculi, and in the follow up of testicular cancer patients. For individuals with chronic conditions warranting frequent radiological follow up, the focus must continue to be the incorporation of appropriate CT use into patient care. This is of particular importance for the paediatric population who are most susceptible to potential radiation induced malignancy.CT technological developments continue to focus on radiation dose optimisation. This article aims to highlight these advancements, which prioritise the acquisition of diagnostically satisfactory images with the least amount of radiation possible.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery

“…Low‐dose NCCT is the most sensitive imaging method to diagnose the urinary calculi, with decreased radiation exposure [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. It allows accurate determination of stone size and volume, stone multiplicity, stone density and state of the renal parenchyma since other means of radiological evaluation (KUB and sonography) fail to give adequate information on these variables.…”

The evolving role of radiological imaging in cystic fibrosis

“…The main limitation to the routine use of chest CT for monitoring PWCF is the significantly higher radiation dose compared with CR, that is effective dose (ED) in adults of 5.4 mSv versus 0.02 mSv, respectively [10 ▪ ]. The increasing life expectancy of PWCF resulting from improved therapies means that more caution should be taken in relation to the lifetime cumulative ionizing radiation in these patients from the routine use of CT, with a 6-fold increase in the use of CT scanning among these patients compared with the general population [6 ▪ ,16 ▪ ]. In addition, age at the time of first exposure to ionizing radiation is an accepted independent risk factor for cancer mortality in subsequent years, with those of a young age being particularly at risk [17].…”

“…In addition, age at the time of first exposure to ionizing radiation is an accepted independent risk factor for cancer mortality in subsequent years, with those of a young age being particularly at risk [17]. This is especially relevant to PWCF given their average age at first chest CT has dropped substantially in recent years, from 20 years for those born pre-1980, to 1.9 years for those born post-1997 [16 ▪ ].…”

“…Hence, several dose reduction strategies have been investigated with the aim of making routine CT imaging safer [6 ▪ ,16 ▪ ,18 ▪ ]. More recently, image reconstruction techniques using advanced iterative reconstruction (IR) algorithms have been introduced which reduce image noise and improve spatial resolution in images acquired with reduced radiation dose to a much greater extent than traditional filtered back projection (FBP) [6 ▪ ,10 ▪ ,16 ▪ ,18 ▪ ]. These include hybrid iterative reconstruction (IR) and more recently pure IR which can be used with both SD-CT and LD-CT. At our institution (CC, OJOC, MMM), which hosts a specialised CF centre, we have replaced routine CR with volumetric ultra-low-dose (ULD) chest CT reconstructed with pure IR (Table 1) after a prospective feasibility study [10 ▪ ] found this protocol could produce diagnostically acceptable images among adults with CF followed up at 12 and 24 months postinitiation of ivacaftor (Kalydeco), the dose being similar to that of a PA and lateral CR, that is, ED of 0.08 mSv for this ULD-CT, 98.5% less than the average ED of 5.4 mSv for a SD-CT chest at our institution (CC, OJOC, MMM), and 94.7% less than that of most currently used LD-CT protocols of 1.5 mSv [6 ▪ ,19].…”

Translating radiography research into practice

“… 17 Further articles discuss change and evidence-based approaches, 18 there is a discussion asking questions about evidence-based approaches in radiography, 19 there is a comparison of radiography against other healthcare professionals in relation to impact/research translation 20 and finally there is an article about dose reduction in computed tomography. 21 …”