Computed tomography in trauma patients using iterative reconstruction: reducing radiation exposure without loss of image quality

Heterogeneity in defining multiple trauma: a systematic review of randomized controlled trials

INTRODUCTION

While numerous randomized controlled trials (RCTs) have been conducted in the field of trauma, a substantial portion of them are yielding negative results. One potential contributing factor to this trend could be the lack of agreement regarding the chosen definitions across different trials. The primary objective was to identify the terminology and definitions utilized for the characterization of multiple trauma patients within randomized controlled trials (RCTs).

METHODS

A systematic review of the literature was performed in MEDLINE, EMBASE and clinicaltrials.gov between January 1, 2002, and July 31, 2022. RCTs or RTCs protocols were eligible if they included multiple trauma patients. The terms employed to characterize patient populations were identified, and the corresponding definitions for these terms were extracted. The subsequent impact on the population recruited was then documented to expose clinical heterogeneity.

RESULTS

Fifty RCTs were included, and 12 different terms identified. Among these terms, the most frequently used were "multiple trauma" (n = 21, 42%), "severe trauma" (n = 8, 16%), "major trauma" (n = 4, 8%), and trauma with hemorrhagic shock" (n = 4, 8%). Only 62% of RCTs (n = 31) provided a definition for the terms used, resulting a total of 21 different definitions. These definitions primarily relied on the injury severity score (ISS) (n = 15, 30%), displaying an important underlying heterogeneity. The choice of the terms had an impact on the study population, affecting both the ISS and in-hospital mortality. Eleven protocols were included, featuring five different terms, with "severe trauma" being the most frequent, occurring six times (55%).

CONCLUSION

This systematic review uncovers an important heterogeneity both in the terms and in the definitions employed to recruit trauma patients within RCTs. These findings underscore the imperative of promoting the use of a unique and consistent definition.

Changing the Patient's Position: Pitfalls and Benefits for Radiation Dose and Image Quality of Computed Tomography in Polytrauma

For computed tomography (CT), representing the diagnostic standard for trauma patients, image quality is essential. The positioning of the patient’s arms next to the abdomen causes artifacts and is also considered to increase radiation exposure. The aim of this study was to evaluate the effect of various positionings during different CT examination steps on the extent of artifacts as well as radiation dose using iterative reconstruction (IR). 354 trauma-CTs were analyzed retrospectively. All datasets were reconstructed using IR and three different examination protocols were applied. Arm elevation led to a significant improvement of the image quality across all examination protocols (p < 0.001). Variation in arm positioning during image acquisition did not lead to a reduction of radiation dose (p = 0.123). Only elevation during scout acquisition resulted in the reduction of radiation exposure (p < 0.001). To receive high-quality CT images, patients should be placed with elevated arms for the trunk scan, as artifacts remain even with the IR. Arm repositioning during the examination itself had no effect on the applied radiation dose because its modulation refers to the initial scout obtained. In order to achieve a dose effect by different positioning, a two-scout protocol (dual scout) should be used.

Current Standards for and Clinical Impact of Emergency Radiology in Major Trauma

In industrialized countries, high energy trauma represents the leading cause of death and disability among people under 35 years of age. The two leading causes of mortality are neurological injuries and bleeding. Clinical evaluation is often unreliable in determining if, when and where injuries should be treated. Traditionally, surgery was the mainstay for assessment of injuries but advances in imaging techniques, particularly in computed tomography (CT), have contributed in progressively changing the classic clinical paradigm for major traumas, better defining the indications for surgery. Actually, the vast majority of traumas are now treated nonoperatively with a significant reduction in morbidity and mortality compared to the past. In this sense, another crucial point is the advent of interventional radiology (IR) in the treatment of vascular injuries after blunt trauma. IR enables the most effective nonoperative treatment of all vascular injuries. Indications for IR depend on the CT evidence of vascular injuries and, therefore, a robust CT protocol and the radiologist's expertise are crucial. Emergency and IR radiologists form an integral part of the trauma team and are crucial for tailored management of traumatic injuries.

CT diagnostics of pulmonary embolism: Does iodine delivery rate still affect image quality in iterative reconstruction?

BACKGROUND

Computed tomographic (CT) imaging in suspected pulmonary artery embolism represents the standard procedure. Studies without iterative reconstruction proved beneficial using increased iodine delivery rate (IDR). This study compares image quality in pulmonary arteries on iteratively reconstructed CT images of patients with suspected pulmonary embolism using different IDR.

MATERIAL AND METHODS

1065 patients were included in the study. Patients in group A (n = 493) received an iodine concentration of 40 g/100 ml (IDR 1.6 g/s) and patients in group B (n = 572) an iodine concentration of 35 g/100 ml (IDR 1.4 g/s) at a flow rate of 4 ml/s. A 80-detector spiral CT scanner with iterative reconstruction was used. We measured mean density values in truncus pulmonalis, both pulmonary arteries and segmental pulmonary arteries. Subjectively, the contrast of apical and basal pulmonary arteries was determined on a 4-point Likert scale.

RESULTS

Radiodensity was significantly higher in all measured pulmonary arteries using the increased IDR (p < 0.001). TP: 483.0 HU vs. 393.4 HU; APD: 452.1 HU vs. 372.1 HU; APS: 448.2 HU vs. 374.4 HU; ASP: 443.9 vs. 374.4 HU. Subjectively assessed contrast enhancement in apical (p = 0.077) and basal (p = 0.429) lung sections showed no significant differences.

CONCLUSION

Higher IDR improves objective image quality in all patients with significantly higher radiodensities by iterative reconstruction. Subjective contrast of apical and basal lung sections did not differ. The number of non-sufficient scans decreased with high IDR.

European Society of Emergency Radiology: guideline on radiological polytrauma imaging and service (short version)

BACKGROUND

Although some national recommendations for the role of radiology in a polytrauma service exist, there are no European guidelines to date. Additionally, for many interdisciplinary guidelines, radiology tends to be under-represented. These factors motivated the European Society of Emergency Radiology (ESER) to develop radiologically-centred polytrauma guidelines.

RESULTS

Evidence-based decisions were made on 68 individual aspects of polytrauma imaging at two ESER consensus conferences. For severely injured patients, whole-body CT (WBCT) has been shown to significantly reduce mortality when compared to targeted, selective CT. However, this advantage must be balanced against the radiation risk of performing more WBCTs, especially in less severely injured patients. For this reason, we recommend a second lower dose WBCT protocol as an alternative in certain clinical scenarios. The ESER Guideline on Radiological Polytrauma Imaging and Service is published in two versions: a full version (download from the ESER homepage, https://www.eser-society.org ) and a short version also covering all recommendations (this article).

CONCLUSIONS

Once a patient has been accurately classified as polytrauma, each institution should be able to choose from at least two WBCT protocols. One protocol should be optimised regarding time and precision, and is already used by most institutions (variant A). The second protocol should be dose reduced and used for clinically stable and oriented patients who nonetheless require a CT because the history suggests possible serious injury (variant B). Reading, interpretation and communication of the report should be structured clinically following the ABCDE format, i.e. diagnose first what kills first.

[Update polytrauma and computed tomography in ongoing resuscitation : ABCDE and "diagnose first what kills first"]

CLINICAL ISSUE

The mean number of trauma room admissions and applied CT dose increase as the severity of injuries decreases. Therefore, appropriateness of established procedures should be re-evaluated.

STANDARD RADIOLOGICAL METHODS

Considering severely injured patients with an Injury Severity Score (ISS) ≥16, whole body CT (WB-CT) compared to selective CT decreased mortality by about 25%. Thus, the ISS is a good indicator for the severity of injuries. However, since ISS can only be determined after diagnosis, it does not help with the primary assessment.

METHODOLOGICAL INNOVATION AND EVALUATION

In addition to the currently used very fast WB-CT protocol with the highest diagnostic precision, a second protocol should be established applying a substantially lower dose. Under ongoing resuscitation, WB-CT often makes a substantial contribution towards targeted therapy or to justifying the discontinuation of resuscitation measures. The WB-CT findings should be performed several times and, at least in the acute emergency situation, it should follow the ABCDE scheme as close as possible.

PRACTICAL RECOMMENDATIONS

In the trauma room it should be initially decided whether the classification as polytrauma is to be maintained. If yes, every institution should provide a dose-reduced WB-CT protocol in addition to the maximum variant used so far. Dose-reduced WB-CT seems to be appropriate for stable and oriented patients, who receive a CT primarily because of the trauma mechanism. Even under resuscitation conditions, WB-CT is easy to perform and medically as well as ethically of high value. The reporting and communication should be structured according to "diagnose first what kills first".

Development of size-specific institutional diagnostic reference levels for computed tomography protocols in neck imaging

PURPOSE

To develop size-specific institutional diagnostic reference levels (DRLs) for computed tomography (CT) protocols used in neck CT imaging (cervical spine CT, cervical CT angiography (CTA) and cervical staging CT) and to compare institutional to national DRLs.

MATERIALS AND METHODS

Cervical CT examinations (spine, n = 609; CTA, n = 505 and staging CT, n = 184) performed between 01/2016 and 06/2017 were included in this retrospective study. For each region and examination, the volumetric CT dose index (CTDI_vol) and dose-length product (DLP) were determined and binned into size bins according to patient water-equivalent diameter (d_w). Linear regression analysis was performed to calculate size-specific institutional DRLs for CTDI_vol and DLP, applying the 75th percentile as the upper limit for institutional DRLs. The mean institutional CTDI_vol and DLP were compared to national DRLs (CTDI_vol 20 mGy for cervical spine CT (DLP 300 mGycm) and cervical CTA (DLP 600 mGycm), and CTDI_vol 15 mGy for cervical staging CT (DLP 330 mGycm)).

RESULTS

The mean CTDI_vol and DLP (±standard deviation) were 15.2 ± 4.1 mGy and 181.5 ± 88.3 mGycm for cervical spine CT; 8.1 ± 4.3 mGy and 280.2 ± 164.3 mGycm for cervical CTA; 8.6 ± 1.9 mGy and 162.8 ± 85.0 mGycm for cervical staging CT. For all CT protocols, there was a linear increase in CTDI_vol and DLP with increasing d_w. For the CTDI_vol, size-specific institutional DRLs increased with d_w from 14 to 29 mGy for cervical spine CT, from 5 to 17 mGy for cervical CTA and from 8 to 13 mGy for cervical staging CT. For the DLP, size-specific institutional DRLs increased with d_w from 130 to 510 mGycm for cervical spine CT, from 140 to 640 mGycm for cervical CTA and from 140 to 320 mGycm for cervical staging CT. Institutional DRLs were lower than national DRLs by 81% and 67% for cervical spine CT (d_w = 17.8 cm), 43% and 51% for cervical CTA (d_w = 19.5 cm) and 59% and 53% for cervical staging CT (d_w = 18.8 cm) for CTDI_vol and DLP, respectively.

CONCLUSION

Size-specific institutional DRLs were generated for neck CT examinations. The mean institutional CTDI_vol and DLP values were well below national DRLs.

Composition and Associated Factors of Radiological Examination in Major Trauma Patients: A Prospective Observational Study

The care of major trauma patients continues to be a challenge for emergency physicians and trauma surgeons. We found that the total number of radiological examinations for major trauma patients in this study was high and mainly comprised radiography and computed tomography (CT), with CT being more commonly adopted. The number of CT scans was positively correlated with severity of injury and intensive care unit length of stay. Further study is warranted to optimize radiological examinations involving major trauma patients.

Low-Dose CT With the Adaptive Statistical Iterative Reconstruction V Technique in Abdominal Organ Injury: Comparison With Routine-Dose CT With Filtered Back Projection

OBJECTIVE. The purpose of this study was to evaluate and compare the diagnostic performance and image quality of low-dose CT performed with adaptive statistical iterative reconstruction (ASIR)-V with those of routine-dose CT with filtered back projection (FBP) in the evaluation of abdominal organ injury. MATERIALS AND METHODS. The study enrolled 197 patients with trauma who underwent multiphase abdominal CT, including routine-dose portal venous phase imaging with FBP and low-dose delayed phase imaging with 50% ASIR-V. The presence of abdominal organ injuries (liver, spleen, pancreas, kidney) was reviewed, and injuries were graded according to American Association for the Surgery of Trauma (AAST) scales. CT detection rates of organ injury and AAST grading with the two protocols were compared by McNemar test. Subjective analysis of image noise and artifacts and objective analysis of CT noise were performed by unpaired t test. RESULTS. Compared with the routine-dose protocol, the low-dose protocol enabled an mean dose reduction of 59.8%. The detection rates and diagnostic performance of AAST grading did not differ significantly between the two protocols (detection rate, p = 0.289; diagnostic performance, p > 0.999). Objective image noise was significantly less with the low-dose protocol than with the routine-dose protocol (p < 0.001). Subjective imaging artifacts were similar between the low-dose and routine-dose protocols (p = 0.539). CONCLUSION. Compared with routine-dose protocol with FBP, low-dose CT with ASIR-V was useful for assessing multiorgan abdominal injury without impairing image quality.

Ordered Subset Expectation Maximum Algorithms Based on Symmetric Structure for Image Reconstruction

In this paper, we propose the symmetric structure of the reconstructed points discretization model to partition and order the subsets of Ordered Subset Expectation Maximum (OSEM) algorithms for image reconstruction and then simplify the calculation of the projection coefficient matrix while satisfying the balancing properties of subsets. The reconstructed points discretization model was utilized to describe the forward and inverse relationships between the reconstructed points and the projection data according to the distance from the point to the ray rather than the intersection length between the square pixel and the ray. This discretization model provides new approaches for improving and constructing the reconstruction algorithms on the basis of the geometry of the model. The experimental results show that the OSEM algorithms based on the reconstructed points discretization model and its geometric symmetry structure can effectively improve the imaging speed and the imaging precision.

Frequency and characteristics of traumatic brain injury in restrained drivers involved in road traffic accidents

BACKGROUND

While seatbelt is an important device protecting drivers from traumatic brain injury (TBI), it has rarely been reported how often and in what circumstances restrained drivers sustain TBI after road traffic accident (RTA). Whole-body computed tomography (WBCT) for blunt trauma patients may provide a unique opportunity to investigate the frequency and characteristics of TBI sustained by restrained drivers.

METHODS

A single-center, retrospective observational study was conducted using prospectively acquired data. Between January 2013 and December 2017, 409 restrained drivers (284 men/125 women, mean age of 45.0 ± 19.1 years) whose vehicle had been severely damaged in RTAs underwent WBCT for evaluation of injuries. Multivariate regression analysis was performed to identify variables predictive of TBI. Influence of collision patterns (frontal, lateral or rollover) on the frequency and severity of TBI was evaluated. Relationship between collision patterns and CT findings was also reviewed.

RESULTS

Thirty-one restrained drivers (7.6%) sustained TBI after RTA. The distribution of Glasgow Coma Scale (GCS) scores among the 31 drivers was 15 in 9, 13-14 in 9, 9-12 in 4, and ≤ 8 in 9, indicating that the majority of TBIs were classifiable as mild. The frequency of TBI in alert and oriented drivers, i.e., those with a GCS score of 15, was 2.9%. Multivariate regression analysis showed that both altered mental status (OR, 4.933; 95% CI, 1.135-21.431) and loss of consciousness (OR, 6.492; 95% CI, 1.669-25.249) were associated with TBI. The frequency of TBI tended to be higher in drivers with rollover collision than those with frontal collision (6 vs. 13%, p = 0.07). Interhemispheric acute subdural hematoma and subcortical petechial hemorrhage seemed to be characteristic CT findings in drivers with frontal and lateral collision, respectively.

CONCLUSIONS

The key finding of this study, i.e., that (1) TBI was observed in 7.6% of restrained drivers with severe vehicular damage, may provide useful information to neurosurgeons who take care of RTA victims. The majority of the TBIs were mild without need for neurosurgical intervention. While association may exist between type of collision and type of brain injury, further studies with prospective design are warranted.

Whole-body computed tomography in severely injured patients

PURPOSE OF REVIEW

To provide an update on the relevant and recent studies on whole-body computed tomography (WBCT) imaging of severely injured patients.

RECENT FINDINGS

The advantages of WBCT in time saving, diagnostic accuracy and even in survival have been proven in numerous studies. WBCT can also be beneficial in haemodynamically unstable major trauma patients. The CT scanner should be located close to the emergency department or even in the trauma room. The issue of radiation is still quite important, however, iterative as well as split-bolus protocols can nowadays reduce radiation significantly. The question: which trauma patient should receive WBCT and which not is not yet solved sufficiently. Postmortem WBCT has a promising potential to promptly define the definitive cause of death of trauma victims comparably to traditional autopsy.

SUMMARY

On account of the recent advances, whole-body CT has become a crucial part of the initial in-hospital assessment of severely injured patients. It is recommended as the standard radiological tool for the emergency diagnostic work-up in major trauma patients.

Routine versus selective chest and abdominopelvic CT-scan in conscious blunt trauma patients: a randomized controlled study

PURPOSE

CT-scan is increasingly used in blunt trauma, but the real impact on patient outcome is still unclear. This study was conducted to assess the effect of performing routine (versus selective) chest and abdominopelvic CT-scan on patient admission time and outcome in blunt trauma.

METHODS

Conscious and hemodynamically stable high-energy trauma patients were included (n = 140). Routine chest and abdominopelvic CT-scan was requested in addition to the conventional radiography and ultrasound for the intervention group and selective CT-scan according to clinical presentation was done for the control group. Patient admission times in the emergency room and surgery ward, complications, and performed surgical procedures were assessed. "Unsuspected injuries" defined as additional findings on CT-scan, which were not expected before CT-scan, were evaluated.

RESULTS

Admission time in the emergency ward and admission time in hospital were significantly shorter in the intervention group. Complications were similar in both groups. Abdominopelvic CT-scan in the intervention group revealed nine (7.8%) unsuspected injuries. All of these nine patients had also a positive clinical examination and injuries in other body regions. Chest CT-scan in the intervention group led to additional diagnoses in 17 patients (24.28%) leading to tube thoracostomy in 13 patients (18.57%).

CONCLUSION

Routine chest and abdominopelvic CT-scan in conscious blunt trauma patients decreases the hospitalization time, but has no impact on patient outcome and probably might lead to overtreatment of occult injuries. The option of using a selective approach should be further evaluated to decrease radiation exposure and facility overuse.

Early computed tomography or focused assessment with sonography in abdominal trauma: what are the leading opinions?

PURPOSE

The initial assessment of severely injured patients in the resuscitation room requires a systematic and quickly performed survey. Whereas the Advanced Trauma Life Support (ATLS^®)-based algorithm recommends focused assessment with sonography in trauma (FAST) among others, recent studies report a survival advantage of early whole-body computed tomography (WBCT) in haemodynamically stable as well as unstable patients. This study assessed the opinions of trauma surgeons about the early use of WBCT in severely injured patients with abdominal trauma, and abdominal CT in patients with isolated abdominal trauma, during resuscitation room treatment.

METHODS

An online cross-sectional survey was performed over 8 months. Members of the Swiss Society for Surgery and the Austrian and German associations for trauma surgery were invited to answer nine online questions.

RESULTS

Overall, 175 trauma surgeons from 155 departments participated. For haemodynamically stable patients, most considered FAST (77.6%) and early CT (82.3%) to be the ideal diagnostic tools. For haemodynamically unstable patients, 93.4% considered FAST to be mandatory. For CT imaging in unstable patients, 47.5% agreed with the use of CT, whereas 52.5% rated early CT as not essential. For unstable patients with pathological FAST and clinical signs, 86.8% agreed to proceed with immediate laparotomy.

CONCLUSIONS

Most surgeons rely on early CT for haemodynamically stable patients with abdominal trauma, whereas FAST is performed with similar frequency and is prioritized in unstable patients. It seems that the results of recent studies supporting early WBCT have not yet found broad acceptance in the surgical community.

Clinical Judgment Is Not Reliable for Reducing Whole-body Computed Tomography Scanning after Isolated High-energy Blunt Trauma

Background

The purpose of this study was to test the diagnostic performance of clinical judgment for the prediction of a significant injury with whole-body computed tomography scanning after high-energy trauma.

Methods

The authors conducted an observational prospective study in a single level-I trauma center. Adult patients were included if they had an isolated high-energy injury. Senior trauma leaders were asked to make a clinical judgment regarding the likelihood of a significant injury before performance of a whole-body computed tomography scan. Clinical judgments were recorded using a probability diagnosis scale. The primary endpoint was the diagnosis of a serious-to-critical lesion on the whole-body computed tomography scan. Diagnostic performance was assessed using receiver operating characteristic analysis.

Results

Of the 354 included patients, 127 patients (36%) had at least one injury classified as abbreviated injury score greater than or equal to 3. The area under the receiver operating characteristic curve of the clinical judgment to predict a serious-to-critical lesion was 0.70 (95% CI, 0.64 to 0.75%). The sensitivity of the clinical judgment was 82% (95% CI, 74 to 88%), and the specificity was 49% (95% CI, 42 to 55%). No patient with a strict negative clinical examination had a severe lesion (n = 19 patients). The sensitivity of the clinical examination was 100% (95% CI, 97 to 100%) and its specificity was 8% (95% CI, 5 to 13%).

Conclusions

Clinical judgment alone is not sufficient to reduce whole-body computed tomography scan use. In patients with a strictly normal physical examination, whole-body computed tomography scanning might be avoided, but this result deserves additional study in larger and more diverse populations of trauma patients.

A new low-dose multi-phase trauma CT protocol and its impact on diagnostic assessment and radiation dose in multi-trauma patients

Purpose

Computed tomography (CT) examinations, often using high-radiation dosages, are increasingly used in the acute management of polytrauma patients. This study compares a low-dose polytrauma multi-phase whole-body CT (WBCT) protocol on a latest generation of 16-cm detector 258-slice multi-detector CT (MDCT) scanner with advanced dose reduction techniques to a single-phase polytrauma WBCT protocol on a 64-slice MDCT scanner.

Methods

Between March and September 2015, 109 polytrauma patients (group A) underwent acute WBCT with a low-dose multi-phase WBCT protocol on a 258-slice MDCT whereas 110 polytrauma patients (group B) underwent single-phase trauma CT on a 64-slice MDCT. The diagnostic accuracy to trauma-related injuries, radiation dose, quantitative and semiquantitative image quality parameters, subjective image quality scorings, and workflow time parameters were compared.

Results

In group A, statistically significantly more arterial injuries (p = 0.04) and arterial dissections (p = 0.002) were detected. In group A, the mean (±SD) dose length product value was 1681 ± 183 mGy*cm and markedly lower when compared to group B (p < 0.001). The SDs of the mean Houndsfield unit values of the brain, liver, and abdominal aorta were lower in group A (p < 0.001). Mean signal-to-noise ratios (SNRs) for the brain, liver, and abdominal aorta were significantly higher in group A (p < 0.001). Group A had significantly higher image quality scores for all analyzed anatomical locations (p < 0.02). However, the mean time from patient registration until completion of examination was significantly longer for group A (p < 0.001).

Conclusions

The low-dose multi-phase CT protocol improves diagnostic accuracy and image quality at markedly reduced radiation. However, due to technical complexities and surplus electronic data provided by the newer low-dose technique, examination time increases, which reduces workflow in acute emergency situations.

Non-traumatic incidental findings in patients undergoing whole-body computed tomography at initial emergency admission

OBJECTIVE

To evaluate the number, localisation and importance of non-traumatic incidental findings (IFs) in patients with suspected or obvious multiple trauma undergoing whole-body CT (WBCT) in a level-1 trauma centre.

METHODS

Between January 2009 and December 2013, a total of 2440 patients with trauma undergoing WBCT at admission to a level-1 trauma centre of a university hospital were retrospectively analysed, through imaging IFs unrelated to trauma with the radiological reports. All IFs were grouped into four categories according to their clinical relevance. Category 1: urgent treatment or further clarification needed; category 2: further examination and follow-up within 3-6 months required; category 3: findings with no immediate consequences for the treatment of the patient but of potential relevance in the future; category 4: harmless findings.

RESULTS

Altogether, 5440 IFs in 2440 patients (1735 male, 705 female; mean age 45.1 years) were documented. In 204 patients (8.4%) urgent category 1 findings were reported, 766 patients (31.4%) had category 2 findings, 1236 patients (50.7%) had category 3 findings and 1173 patients (48.1%) had category 4 findings. Most IFs were detected in the abdomen/pelvis (42.5%). 602 (24.7%) of the patients had no IFs.

CONCLUSIONS

WBCT scans of unrelated trauma patients demonstrate a high rate of IF. A substantial percentage (8.4%) of patients had urgent category 1IFs and a high percentage (31.4%) had category 2 IFs requiring a follow-up. This high number of patients with polytrauma undergoing WBCT, having IFs of high relevance, poses a major challenge for the level-1 trauma centre in the acute and postacute management of these patients.

Reducing radiation exposure with iterative reconstruction: an inter- and intra-scanner analysis

Our purpose in this study was to compare delivered radiation exposure via computed tomography dose index volume (CTDI_vol) and dose length production (DLP) measurements from computed tomography (CT) examinations performed on scanners with and without image-quality enhancing iterative reconstruction (IR) software. A retrospective analysis was conducted on randomly selected chest, abdomen, and/or pelvis CT examinations from three different scanners from 1 January 2013 to 31 December 2013. CTDI_vol and DLP measurements were obtained from two CT scanners with and one CT scanner without IR software. To evaluate inter-scanner variability, we compared measurements from the same model CT scanners, one with and one without IR software. To evaluate intra-scanner variability, we compared measurements between two scanners with IR software from different manufacturers. CT scanners with IR software aided in the overall reduction in radiation exposure, measured as CTDI_vol by 30% and DLP by 39% when compared to a scanner without IR. There was no significant difference in CTDl_vol or DLP measurements across different manufacturers with IR software. As a result, IR software significantly decreased the radiation exposure to patients, but there were no differences in radiation measurements across CT manufacturers with IR software.

Dose reduction in paediatric cranial CT via iterative reconstruction: a clinical study in 78 patients

AIM

To assess how adaptive statistical iterative reconstruction (ASIR) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT) in children.

MATERIALS AND METHODS

Non-contrast cranial CT acquired in 78 paediatric patients (age 0-12 years) were evaluated. The images were acquired and processed using four different protocols: Group A (control): 120 kV, filtered back projection (FBP), n=18; Group B: 100 kV, FBP, n=22; Group C: 100 kV, scan and reconstruction performed with 20% ASIR, n=20; Group D1: 100 kV, scan and reconstruction performed with 30% ASIR, n=18; Group D2: raw data from Group D1 reconstructed using a blending of 40% ASIR and 60% FBP, n=18. The effective dose was calculated and the image quality was assessed quantitatively and qualitatively.

RESULTS

Compared to Group A, Groups C and D1/D2 showed a significant reduction of the dose-length product (DLP) by 34.4% and 64.4%, respectively. All experimental groups also showed significantly reduced qualitative levels of noise, contrast, and overall diagnosability. Diagnosis-related confidence grading showed Group C to be adequate for everyday clinical practice. Quantitative measures of Groups B and C were comparable to Group A with only few parameters compromised. Quantitative scores in Groups D1 and D2 were mainly lower compared to Group A, with Group D2 performing better than Group D1. Group D2 was considered adequate for follow-up imaging of severe acute events such as bleeding or hydrocephalus.

DISCUSSION

The use of ASIR combined with low tube voltage may reduce radiation significantly while maintaining adequate image quality in non-contrast paediatric cCT.

Cumulative doses analysis in young trauma patients: a single-centre experience

Multidetector computed tomography (MDCT) represents the main source of radiation exposure in trauma patients. The radiation exposure of young patients is a matter of considerable medical concern due to possible long-term effects. Multiple MDCT studies have been observed in the young trauma population with an increase in radiation exposure. We have identified 249 young adult patients (178 men and 71 women; age range 14-40 years) who had received more than one MDCT study between June 2010 and June 2014. According to the International Commission on Radiological Protection publication, we have calculated the cumulative organ dose tissue-weighting factors by using CT-EXPO software(®). We have observed a mean cumulative dose of about 27 mSv (range from 3 to 297 mSv). The distribution analysis is characterised by low effective dose, below 20 mSv, in the majority of the patients. However, in 29 patients, the effective dose was found to be higher than 20 mSv. Dose distribution for the various organs analysed (breasts, ovaries, testicles, heart and eye lenses) shows an intense peak for lower doses, but in some cases high doses were recorded. Even though cumulative doses may have long-term effects, which are still under debate, high doses are observed in this specific group of young patients.