Computed Tomography Radiation Dose Research Articles

Radiation exposure of patients undergoing multiple-slice CT scans in Romania

Abstract Ionizing radiation is largely used in medicine due to its role in the diagnosis and treatment of patients. In the past 50 years computed tomography (CT) has become indispensable for medical practice because it offers sub-millimeter cross-sectional imaging of any region of the body. New CT scanners use thinner slices, providing more accurate results, but also an increased radiation exposure with possible long-term harmful effects for the patients. The parameter used as an indicator of radiation dose in CT is the dose-length product (DLP). The study included 4507 patients who were CT scanned using a 16, 32, 64 or 128-slice CT machine. DLP was measured for head, sinuses, thorax, abdomen, pelvis, abdomen+pelvis, and trunk scans - regions for which the health authorities have established national diagnostic reference levels (DRL - the expected radiation dose received by a patient in CT). One-way ANOVA was used to analyse data considering the use of contrast agents, the gender, age, and weight of patients. Average DLP values were higher (up to 80%) than national DRL for all regions in 64 and 128-slice scans. The highest DLP values were registered in contrast CT for all scanners (p < 0.01); the maximum average (a threefold increase compared to DRL) was measured in the 32-slice sinuses contrast CT. Average DLP correlated with patients’ gender and weight (p < 0.01), but the influence was lower compared to the use of contrast agents. In conclusion, CT scans acquired using thinner slices lead to more accurate results and high-quality images, but the study suggests an increased radiation exposure. CT has an uncontestable contribution to a precise and rapid diagnosis, but more attention must be given to the stochastic effects risks associated with the radiation dose received during a CT scan. Are all scans necessary? Do all patients really need to receive high doses? The role of the practitioner is decisive, and the justifiable process is “a must” in all radiodiagnosis practices. Key messages • CT doses must be kept “as low as reasonably achievable” while maintaining diagnostic image quality. • Justification, dose limitation, and optimisation are fundamental principles of radioprotection.

Preoperative Planning for Shoulder Arthroplasty is Feasible with Computed Tomography at Lower-Than-Conventional Radiation Doses

Computed tomography (CT) offers a detailed assessment of the shoulder for preoperative shoulder arthroplasty planning; however, this technique exposes the patient to ionizing radiation. The purpose of this study was to prospectively evaluate the practicality of reducing the CT radiation dose compared to conventional dose levels for manual and preoperative planning software measurements for shoulder arthroplasty. A total of 10 shoulder CT examinations were performed for preoperative planning purposes on a dual x-ray source CT scanner. A specialized dose-split scan technique was utilized to reconstruct CT images corresponding to 100%, 70%, and 30% radiation dose relative to our institution's standard of care imaging protocol. Glenoid version, inclination, and humeral head subluxation were measured manually by three authors and by commercially available software platforms. These measurements were analyzed for agreement between the 100%, 70%, and 30% dose levels for each patient. Tolerances of 5° of glenoid version, 5° of glenoid inclination, and 10% humeral head subluxation were used as equivalent for preoperative planning. Automated measurements of 70% dose images were within 5° of version, 5° of inclination, and 10% subluxation in 95.0% of cases. Manual measurements of 70% RD images were within 5° of version for 90.0% of cases, 5° of inclination in 86.7% of cases, and 10% subluxation in 100% of cases. Automated measurements from the 30% dose images were within 5° of version, 5° of inclination, and 10% subluxation for 100% of cases. Manual measurements from the 30% dose images were within 5° of version for 86.7% of cases, 5° of inclination in 76.7% of cases, and 10% subluxation in 100% of cases. The mean absolute difference in software measurement of glenoid version (p = 0.96), glenoid inclination (p = 0.64), or humeral head subluxation (p = 0.09) or in aggregated manual mean absolute difference of version (p = 0.22), inclination (p = 0.31), or humeral head subluxation (p = 0.56) was not significant. Good to excellent reliability was determined by interclass correlation coefficients among the manual observers and automatic software platforms for measurements at all doses (P<0.001) CONCLUSIONS: The results indicate that both preoperative planning software platforms and human observers produced similar measurements of glenoid version, inclination, and humeral head subluxation from reduced-dose images compared to standard of care doses. By implementing reduced dose techniques in preoperative shoulder CT, the potential risks associated with radiation exposure could be reduced for patients undergoing shoulder arthroplasty.

Effects of organ dose modulation applied to a part of the scan range on radiation dose in computed tomography of the body

In computed tomography (CT), organ dose modulation (ODM) reduces radiation exposure from the anterior side to reduce radiation dose received by the radiosensitive organs located anteriorly. We investigated the effects of ODM applied to a part of the scan range on radiation dose in body CT. The thorax and thoraco-abdominopelvic region of an anthropomorphic whole-body phantom were imaged with and without ODM. ODM was applied to various regions, and the tube current modulation curves were compared. Additionally, the dose indices were compared with and without ODM in thoracic and thoraco-abdominopelvic CTs in 800 patients. ODM was applied to the thyroid in male patients and to the thyroid and breast in female patients. In phantom imaging of the thorax, the application of ODM below the scan range decreased the tube current, and that to the breast showed a further decrease. Decreased tube current was also observed in phantom imaging of the thoraco-abdominopelvic regions with ODM below the scan range, and the application of ODM to the whole scan range, thyroid, breast, and both thyroid and breast further reduced the tube current in the region to which ODM was applied. In patient imaging, the dose indices were significantly lower with ODM than without ODM, regardless of the scan range or sex. The absolute reduction in dose-length product was larger for thoraco-abdominopelvic CT (male, 43.2 mGy cm; female, 59.7 mGy cm) than for thoracic CT (male, 30.8 mGy cm; female, 37.6 mGy cm) in both sexes, indicating dose reduction in the abdominopelvic region to which ODM was not applied. In conclusion, The application of ODM in body CT reduces radiation dose not only in the region to which ODM is applied but also outside the region. In radiation dose management, it should be considered that even ODM applied to a limited region affects the dose indices.

A Segmentation-based Automated Calculation of Patient Size and Size-specific Dose Estimates in Pediatric Computed Tomography Scans.

Size-specific dose estimates (SSDE) have been introduced into computed tomography (CT) dosimetry to tailor patients' unique sizes to facilitate accurate CT radiation dose quantification and optimization. The purpose of this study was to develop and validate an automated algorithm for the determination of patient size (effective diameter) and SSDE. A MATLAB platform was used to develop software of algorithms based on image segmentation techniques to automate the calculation of patient size and SSDE. The algorithm was used to automatically estimate the individual size and SSDE of four CT dose index phantoms and 80 CT images of pediatric patients comprising head, thorax, and abdomen scans. For validation, the American Association of Physicists in Medicine (AAPM) manual methods were used to determine the patient's size and SSDE for the same subjects. The accuracy of the proposed algorithm in size and SSDE calculation was evaluated for agreement with the AAPM's estimations (manual) using Bland-Altman's agreement and Pearson's correlation coefficient. The normalized error, system bias, and limits of agreement (LOA) between methods were derived. The results demonstrated good agreement and accuracy between the automated and AAPM's patient size estimations with an error rate of 1.9% and 0.27% on the patient and phantoms study, respectively. A 1% percentage difference was found between the automated and manual (AAPM) SSDE estimates. A strong degree of correlation was seen with a narrow LOA between methods for clinical study (r > 0.9771) and phantom study (r > 0.9999). The proposed automated algorithm provides an accurate estimation of patient size and SSDE with negligible error after validation.

Age-based diagnostic reference levels and achievable doses for paediatric CT: a survey in Shanghai, China

Computed tomography (CT) is extensively utilised in medical diagnostics due to its notable radiographic superiority. However, the cancer risk associated with CT examinations, particularly in children, is of significant concern. The assessment of cancer risk relies on the radiation dose to examinees. Diagnostic reference levels (DRLs) and achievable doses (ADs) were used to assess the level of radiation dose in CT examinations widely. Although the national DRLs of paediatric CT have been explored in China, few local DRLs at the city level have been assessed. To set up the local DRLs and ADs of paediatric CT, we investigated the radiation dose level for paediatric CT in Shanghai. In this survey, a total of 3061 paediatric CT examinations underwent in Shanghai in 2022 were selected by stratified sampling, and the dose levels in terms of volume CT dose index (CTDIvol) and the dose-length product (DLP) were analysed by 4 age groups. The DRLs and ADs were set at the 75th and 50th percentile of the distribution and compared with the previous studies at home and abroad. The survey results revealed that, for head scan, the DRLs of CTDIvol were from 25 to 46 mGy, and the levels of DLP were from 340 to 663 mGy·cm. For chest, the DRLs of CTDIvol were from 2.2 to 8.3 mGy, and the levels of DLP were from 42 to 223 mGy·cm. For abdomen, the DRLs of CTDIvol were from 6.3 to 16 mGy, and the levels of DLP were from 181 to 557 mGy·cm. The ADs were about 60% lower than their corresponding DRLs. The levels of radiation doses in children-based hospitals were higher than those in other medical institutions (P < 0.001). In conclusion, there was still potential for reducing radiation dose of paediatric CT, emphasising the urgent need for optimising paediatric CT dose in Shanghai.

National and local diagnostic reference levels for adult 18F-FDG and CT in Jordanian PET/CT: findings and implications in practice

This study aims to report the findings of Jordanian national diagnostic reference level (NDRL) survey for fluorodeoxyglucose (18F-FDG) and local diagnostic reference level (LDRL) of computed tomography (CT) used for attenuation correction and anatomical localisation (AC-AL); and AC and diagnostic CT (AC-DX) within the context of whole-body WB and half-body HB adult oncology PET/CT scanning. Two-structured questionnaires were prepared to gather the necessary information: dosimetry data, patient demographics, equipment specification, and acquisition protocols for identified 18F-FDG PET/CT procedures. The NDRL and achievable dose were reported based on the 75th and 50th percentiles for 18F-FDG administered activity (AA), respectively. The LDRL was reported based on the 50th percentile for (CTDIvol) and (DLP). Data from 562 patients from four Jordanian PET/CT centres were collected. The survey revealed that Jordanian NDRL for AA (303 MBq) was within the acceptable range compared to the published-peer NDRL data (240–590 MBq). However, the 18F-FDG AA varied across the participated PET/CT centres. The reported LDRL CTDIvol and DLP of CT used for (AC-AL) was 4.3 mGy and 459.3 mGy.cm for HB CT scan range, and 4.1 mGy and 659.9 mGy.cm for WB CT scans. The reported LDRL for CTDIvol and DLP for HB CT was higher when compared with the United Kingdom (3.2 mGy and 310 mGy.cm). Concurrently, in the context of WB CT, the reported values (i.e. CTDIvol and DLP) were also higher than both Kuwait (3.6 mGy and 659 mGy.cm) and Slovenia (3.6 mGy and 676 mGy.cm). The reported HB CT(AC-DX) was higher than Nordic, New Zealand and Swiss NDRLs and for WB (AC-DX) CT it was higher than Swiss NDRLs. This study reported the first Jordanian NDRL for 18F-FDG and LDRL for HB and WB CT associated with 18F-FDG PET/CT scans. This data is useful for Jordanian PET/CT centres to compare their LDRL to the suggested DRLs and utilise it in the process of optimising CT radiation doses.

Customised weight-based volume contrast media protocol for multiphase abdominal computed tomography.

Multiphase computed tomography (CT) using fixed volume contrast media may lead to high radiation exposure and toxicity in patients with low body weight. We evaluated a customised weight-based protocol for multiphase CT in terms of radiation exposure, image quality and cost savings. A total of 224 patients were recruited. An optimised CT protocol was applied using 100 kV and 1 mL/kg of contrast media dosing. The image quality and radiation dose exposure of this CT protocol were compared to those of a standard 120 kV, 80 mL fixed volume protocol. The radiation dose information and CT Hounsfield units were recorded. The signal-to-noise ratio, contrast-to-noise ratio (CNR) and figure of merit (FOM) were used as comparison metrics. The images were assessed for contrast opacification and visual quality by two radiologists. The renal function, contrast media volume and cost were also evaluated. The median effective dose was lowered by 16% in the optimised protocol, while the arterial phase images achieved significantly higher CNR and FOM. The radiologists' evaluation showed more than 97% absolute agreement with no significant differences in image quality. No significant differences were found in the pre- and post-CT estimated glomerular filtration rate. However, contrast media usage was significantly reduced by 1,680 mL, with an overall cost savings of USD 421 in the optimised protocol. The optimised weight-based protocol is cost-efficient and lowers radiation dose while maintaining overall contrast enhancement and image quality.

Investigating the Effect of Patient-Related Factors on Computed Tomography Radiation Dose Using Regression and Correlation Analysis

Computed tomography (CT) is a widely utilized diagnostic imaging modality in medicine. However, the potential risks associated with radiation exposure necessitate investigating CT exams to minimize unnecessary radiation. The objective of this study is to evaluate how patient-related parameters impact the CT dose indices for different CT exams. In this study, a dataset containing CT dose information for a cohort of 333 patients categorized into four CT exams, chest, cardiac angiogram, cardiac calcium score and abdomen/pelvis, was collected and retrospectively analyzed. Regression analysis and Pearson correlation were applied to estimate the relationships between patient-related factors, namely body mass index (BMI), weight and age as input variables, and CT dose indices, namely the volume CT dose index (CTDIvol), dose length product (DLP), patient effective dose (ED) and size-specific dose estimate (SSDE), as output variables. Moreover, the study investigated the correlation between the different CT dose indices. Using linear regression models and Pearson correlation, the study found that all CT dose indices correlate with BMI and weight in all CT exams with varying degrees as opposed to age, which did not demonstrate any significant correlation with any of the CT dose indices across all CT exams. Moreover, it was found that using multiple regression models where multiple input variables are considered resulted in a higher correlation with the output variables than when simple regression was used. Investigating the relationships between the different dose indices, statistically significant relationships were found between all dose indices. A stronger linear relationship was noticed between CTDIvol and DLP compared to the relationships between each pair of the other dose indices. The findings of this study contribute to understanding the relationships between patient-related parameters and CT dose indices, aiding in the development of optimized CT exams that ensure patient safety while maintaining the diagnostic efficacy of CT imaging.

Usefulness of the spectral shaping dual-source computed tomography imaging technique in posterior corrective fusion for adolescent idiopathic scoliosis.

Since childhood exposure to radiation has been demonstrated to increase cancer risk with increase in radiation dose, reduced radiation exposure during computed tomography (CT) evaluation is desired for adolescent idiopathic scoliosis (AIS). Therefore, this retrospective study aimed to investigate the radiation dose of dual-source CT using a spectral shaping technique and the accuracy of the thoracic pedicle screw (TPS) placement for posterior spinal fusion (PSF) in patients with AIS. Fifty-nine female patients with thoracic AIS who underwent PSF using CT-guided TPSs were included and divided into two groups comprised of 23 patients who underwent dual-source CT (DSCT) with a tin filter (DSCT group) and 36 who underwent conventional multislice CT (MSCT group). We assessed the CT radiation dose using the CT dose index (CTDIvol), effective dose (ED), and accuracy of TPS insertion according to the established Neo's classification. The DSCT and MSCT groups differed significantly (p < 0.001) in the mean CTDIvol (0.76 vs. 3.31mGy, respectively) and ED (0.77 vs. 3.47mSv, respectively). Although the correction rate of the main thoracic curve in the DSCT group was lower (65.7% vs. 71.2%) (p = 0.0126), the TPS accuracy (Grades 0-1) was similar in both groups (381 screws [88.8%] vs. 600 screws [88.4%], respectively) (p = 0.8133). No patient required replacement of malpositioned screws. Spectral shaping DSCT with a tube-based tin filter allowed a 75% radiation dose reduction while achieving TPS insertion accuracy similar to procedures based on conventional CT without spectral shaping.

Establishment of a local diagnostic reference level for computed tomography chest and abdomen in two different cities in Saudi Arabia

Background and aimSpiral computed tomography (CT) scans, which are considered a high-contrast resolution, quick and cross-sectional imaging technique, have grown in popularity as a result of technological advancements. However, these advancements have brought with them the potential for significantly increased radiation doses to the patient. Consequently, many organizations recommended optimization and establishing diagnostic reference levels. The aim of the current study was to assess CT radiation dose and propose a local diagnostic reference level (LDRL) for the adult trunk [chest and abdomen] using CT dose parameters such as CT dose index volume (CTDIvol) and dose length product (DLP) as well as to compare the practices for aforementioned examinations between two hospitals in Taif and Abha cities in Saudi Arabia. Materials and methodsData from 428 patients (216 for abdomen and 212 for chest) who were examined in two hospitals in Taif and Abha City in Saudi Arabia from December 2022 to March 2023, are used in this study. The data for hospitals in Taif and Abha are presented as ‘T’ and ‘A’ throughout this manuscript. The parameters of exposure and slice thickness were recorded in a specially designed data sheet together with the gender, age and patients morphometric. Microsoft Excel version 2010 was used to analyze results and plot the figures. The LDRL was achieved from the third quartile of CTDIvol and DLP for each hospital and examination. ResultsThe average DLP (mGy-cm) and CTDIvol (mGy) for the chest and abdomen were 243 mGy cm, 5.8 mGy and 549 mGy cm, 8.6 mGy respectively. The average effective dose (ED) for chest and abdomen were 5.10 and 21.10 mSv, respectively. The proposed LDRL for the chest and abdomen were 6.9 mGy (CTDIvol), 375 mGy-cm (DLP), 7.8 mGy (CTDIvol), and 747 (DLP) mGy-cm, respectively. ConclusionHospital ‘A’ irradiated patients with a higher dose for the abdomen exam than Hospital ‘T’, but both hospitals agreed on the amount of radiation dose received by patients for chest imaging. The proposed LDRL for two examinations was less than the DRL obtained from the literature.

Ultra-low dose CT scanning for PET/CT.

The use of computed tomography (CT) for attenuation correction (AC) in whole-body PET/CT can result in a significant contribution to radiation exposure. This can become a limiting factor for reducing considerably the overall radiation exposure of the patient when using the new long axial field of view (LAFOV) PET scanners. However, recent CT technology have introduced features such as the tin (Sn) filter, which can substantially reduce the CT radiation dose. The purpose of this study was to investigate the ultra-low dose CT for attenuation correction using the Sn filter together with other dose reduction options such as tube current (mAs) reduction. We explore the impact of dose reduction in the context of AC-CT and how it affects PET image quality. The study evaluated a range of ultra-low dose CT protocols using five physical phantoms that represented a broad collection of tissue electron densities. A long axial field of view (LAFOV) PET/CT scanner was used to scan all phantoms, applying various CT dose reduction parameters such as reducing tube current (mAs), increasing the pitch value, and applying the Sn filter. The effective dose resulting from the CT scans was determined using the CTDIVol reported by the scanner. Several voxel-based and volumes of interest (VOI)-based comparisons were performed to compare the ultra-low dose CT images, the generated attenuation maps, and corresponding PET images against those images acquired with the standard low dose CT protocol. Finally, two patient datasets were acquired using one of the suggested ultra-low dose CT settings. By incorporating the Sn filter and adjusting mAs to the lowest available value, the radiation dose in CT images of PBU-60 phantom was significantly reduced; resulting in an effective dose of nearly 2% compared to the routine low dose CT protocols currently in clinical use. The assessment of PET images using VOI and voxel-based comparisons indicated relative differences (RD%) of under 6% for mean activity concentration (AC) in the torso phantom and patient dataset and under 8% for a source point in the CIRS phantom. The maximum RD% value of AC was 14% for the point source in the CIRS phantom. Increasing the tube current from 6 mAs to 30 mAs in patients with high BMI, or with arms down, can suppress the photon starvation artifact, whilst still preserving a dose reduction of 90%. Introducing a Sn filter in CT imaging lowers radiation dose by more than 90%. This reduction has minimal effect on PET image quantification at least for patients without Body Mass Index (BMI) higher than 30. Notably, this study results need validation using a larger clinical PET/CT dataset in the future, including patients with higher BMI.

Ultra-low-dose CT for attenuation correction: dose savings and effect on PET quantification for protocols with and without tin filter

BackgroundUltra-low-dose (ULD) computed tomography (CT) scans should be used when CT is performed only for attenuation correction (AC) of positron emission tomography (PET) data. A tin filter can be used in addition to the standard aluminium bowtie filter to reduce CT radiation dose to patients. The aim was to determine how low CT doses can be, when utilised for PET AC, with and without the tin filter, whilst providing adequate PET quantification.MethodsA water-filled NEMA image quality phantom was imaged in three configurations with 18F-FDG: (1) water only (0HU); (2) with cylindrical insert containing homogenous mix of sand, flour and water (SFW, approximately 475HU); (3) with cylindrical insert containing sand (approximately 1100HU). Each underwent one-bed-position (26.3 cm) PET-CT comprising 1 PET and 13 CT acquisitions. CT acquisitions with tube current modulation were performed at 120 kV/50 mAs-ref (reference standard), 100 kV/7 mAs-ref (standard ULDCT for PET AC protocol), Sn140kV (mAs range 7–50-ref) and Sn100kV (mAs range 12–400-ref). PET data were reconstructed with μ-maps provided by each CT dataset, and PET activity concentration measured in each reconstruction. Differences in CT dose length product (DLP) and PET quantification were determined relative to the reference standard.ResultsAt each tube voltage, changes in PET quantification were greater with increasing density and reducing mAs. Compared with the reference standard, differences in PET quantification for the standard ULDCT protocol for the three phantoms were ≤ 1.7%, with the water phantom providing a DLP of 7mGy.cm. With tin filter at Sn100kV, differences in PET quantification were negligible (≤ 1.2%) for all phantoms down to 50mAs-ref, proving a DLP of 2.8mGy.cm, at 60% dose reduction compared with standard ULDCT protocol. Below 50mAs-ref, differences in PET quantification were > 2% for at least one phantom (2.3% at 25mAs-ref in SFW; 6.4% at 12mAs-ref in sand). At Sn140kV/7mAs-ref, quantification differences were ≤ 0.6% in water, giving 3.8mGy.cm DLP, but increased to > 2% at bone-equivalent densities.ConclusionsCT protocols for PET AC can provide ultra-low doses with adequate PET quantification. The tin filter can allow 60–87% lower dose than the standard ULDCT protocol for PET AC, depending on tissue density and accepted change in PET quantification.

Reduced-dose CT in detecting solid liver tumors: A comparison of image quality between automatic exposure control and organ effective modulation

PurposeTo evaluate the subjective and objective image quality of solid liver tumors as well as the radiation dose using organ effective modulation (OEM) technology for abdominopelvic computed tomography (CT). Material and methodsA total of 74 patients who underwent contrast-enhanced abdominopelvic CT between January and April 2022 were prospectively enrolled in this study. Patients were randomly assigned to two groups: the non-OEM group underwent CT scans with automatic exposure control (AEC), while the OEM group underwent CT scans with OEM. The radiation dose was compared between the two groups. Objective image quality was quantitatively assessed using image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Two experienced radiologists independently evaluated the CT images (5, best; 1, worst) by four characteristics including sharpness, contrast, noise, and diagnostic confidence. ResultsThe OEM group presented a significant reduction in volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED) by 11.4%, 12.2%, and 12.2%, respectively (p < 0.05). There were no significant differences between two groups concerning image noise, SNR, and CNR (p > 0.05). Expect for the left and right liver lobes in portal images, OEM was slightly higher than the non-OEM (p < 0.05). The subjective scores of two radiologists demonstrated good agreement (kappa value = 0.84). No statistically significant differences were observed in subjective grading (p > 0.05). ConclusionOEM technology can effectively reduce the radiation dose of abdominopelvic-enhanced CT without affecting the subjective and objective image quality of solid liver tumors.

Accuracy, Hemorrhagic Complications and CT Radiation Dose of Emergency External Ventricular Drain (EVD) Placement in Pediatric Patients: A 15-Year Retrospective Analysis.

To assess accuracy, the frequency of hemorrhagic complications and computed tomography (CT) radiation dose parameters in pediatric patients undergoing landmark-guided external ventricular drain (EVD) placement in an emergency setting. Retrospective analysis comprised 36 EVD placements with subsequent CT control scans in 29 patients (aged 0 to 17 years) in our university hospital from 2008 to 2022. The position of the EVD as well as the presence and extension of bleeding were classified according to previously established grading schemes. Dose length product (DLP), volume-weighted CT dose index (CTDIvol) and scan length were extracted from the radiation dose reports and compared to the diagnostic reference values (DRLs) issued by the German Federal Office for Radiation Protection. After the initial EVD placement, optimal positioning of the catheter tip into the ipsilateral frontal horn or third ventricle (Grade I), or a functional positioning in the contralateral lateral ventricle or the non-eloquent cortex (Grade II), was achieved in 28 and 8 cases, respectively. In 32 of 36 procedures, no evidence of hemorrhage was present in the control CT scan. Grade 1 (<1 mL) and Grade 2 (≥1 to 15 mL) bleedings were detected after 3 and 1 placement(s), respectively. For control scans after EVD placements, CTDIvol (median [25%; 75% quartile]) was 39.92 [30.80; 45.55] mGy, DLP yielded 475.50 [375.00; 624.75] mGy*cm and the scan length result was 136 [120; 166] mm. Exceedances of the DRL values were observed in 14.5% for CTDIvol, 12.7% for DLP and 65.6% for the scan length. None of these values was in the range requiring a report to the national authorities. Landmark-based emergency EVD placement in pediatric patients yielded an optimal position in most cases already after the initial insertion. Complications in terms of secondary hemorrhages are rare. CT dose levels associated with the intervention are below the reportable threshold of the national DRLs in Germany.

Lowering head computed tomography radiation dose for craniosynostosis: An institutional change and review of literature

Definitive diagnosis of Craniosynostosis (CS) with computed tomography (CT) is readily available, however, exposure to ionizing radiation is often a hard stop for parents and practitioners. Lowering head CT radiation exposure helps mitigate risks and improves diagnostic utilization. The purpose of the study is to quantify radiation exposure from head CT in patients with CS using a ‘new’ (ultra-low dose) protocol; compare prior standard CT protocol; summarize published reports on cumulative radiation doses from pediatric head CT scans utilizing other low-dose protocols. A retrospective study was conducted on patients undergoing surgical correction of CS, aged less than 2 years, between August 2014 and February 2022. Cumulative effective dose (CED) in mSv was calculated, descriptive statistics were performed, and mean ± SD was reported. A literature search was conducted describing cumulative radiation exposure from head CT in pediatric patients and analyzed for ionizing radiation measurements. Forty-four patients met inclusion criteria: 17 females and 27 males. Patients who obtained head CT using the ‘New’ protocol resulted in lower CED exposure of 0.32 mSv ± 0.07 compared to the prior standard protocol at 5.25 mSv ± 2.79 (p &lt; 0.0001). Five studies specifically investigated the reduction of ionizing radiation from CT scans in patients with CS via the utilization of low-dose CT protocols. These studies displayed overall CED values ranging from 0.015 mSv to 0.77 mSv. Our new CT protocol resulted in 94% reduction of ionizing radiation. Ultra-low dose CT protocols provide similar diagnostic data without loss of bone differentiation in CS and can be easily incorporated into the workflow of a children’s hospital.

Lowering head computed tomography radiation dose for craniosynostosis: An institutional change and review of literature

Definitive diagnosis of Craniosynostosis (CS) with computed tomography (CT) is readily available, however, exposure to ionizing radiation is often a hard stop for parents and practitioners. Lowering head CT radiation exposure helps mitigate risks and improves diagnostic utilization. The purpose of the study is to quantify radiation exposure from head CT in patients with CS using a ‘new’ (ultra-low dose) protocol; compare prior standard CT protocol; summarize published reports on cumulative radiation doses from pediatric head CT scans utilizing other low-dose protocols. A retrospective study was conducted on patients undergoing surgical correction of CS, aged less than 2 years, between August 2014 and February 2022. Cumulative effective dose (CED) in mSv was calculated, descriptive statistics were performed, and mean ± SD was reported. A literature search was conducted describing cumulative radiation exposure from head CT in pediatric patients and analyzed for ionizing radiation measurements. Forty-four patients met inclusion criteria: 17 females and 27 males. Patients who obtained head CT using the ‘New’ protocol resulted in lower CED exposure of 0.32 mSv ± 0.07 compared to the prior standard protocol at 5.25 mSv ± 2.79 (p &lt; 0.0001). Five studies specifically investigated the reduction of ionizing radiation from CT scans in patients with CS via the utilization of low-dose CT protocols. These studies displayed overall CED values ranging from 0.015 mSv to 0.77 mSv. Our new CT protocol resulted in 94% reduction of ionizing radiation. Ultra-low dose CT protocols provide similar diagnostic data without loss of bone differentiation in CS and can be easily incorporated into the workflow of a children’s hospital.

Bone biopsies guided by augmented reality: a pilot study

PurposeTo test the technical feasibility of an augmented reality (AR) navigation system to guide bone biopsies.MethodsWe enrolled patients subjected to percutaneous computed tomography (CT)-guided bone biopsy using a novel AR navigation system. Data from prospectively enrolled patients (AR group) were compared with data obtained retrospectively from previous standard CT-guided bone biopsies (control group). We evaluated the following: procedure duration, number of CT passes, patient’s radiation dose (dose-length product), complications, and specimen adequacy. Technical success was defined as the ability to complete the procedure as planned, reaching the target center. Technical efficacy was assessed evaluating specimen adequacy.ResultsEight patients (4 males) aged 58 ± 24 years (mean ± standard deviation) were enrolled in the AR group and compared with 8 controls (4 males) aged 60 ± 15 years. No complications were observed. Procedure duration, number of CT passes, and radiation dose were 22 ± 5 min, 4 (median) [4, 6 interquartile range] and 1,034 ± 672 mGy*cm for the AR group and 23 ± 5 min, 9 [7.75, 11.25], and 1,954 ± 993 mGy*cm for controls, respectively. No significant differences were observed for procedure duration (p = 0.878). Conversely, number of CT passes and radiation doses were significantly lower for the AR group (p < 0.001 and p = 0.021, respectively). Technical success and technical efficacy were 100% for both groups.ConclusionsThis AR navigation system is safe, feasible, and effective; it can decrease radiation exposure and number of CT passes during bone biopsies without increasing duration time.Relevance statementThis augmented reality (AR) navigation system is a safe and feasible guidance for bone biopsies; it may ensure a decrease in the number of CT passes and patient’s radiation dose.Key points• This AR navigation system is a safe guidance for bone biopsies.• It ensures decrease of number of CT passes and patient’s radiation exposure.• Procedure duration was similar to that of standard CT-guided biopsy.• Technical success was 100% as in all patients the target was reached.• Technical efficacy was 100% as the specimen was adequate in all patients.Graphical

Deep learning-based body weight from scout images can be an alternative to actual body weight in CT radiation dose management.

Accurate body weight measurement is essential to promote computed tomography (CT) dose optimization; however, body weight cannot always be measured prior to CT examination, especially in the emergency setting. The aim of this study was to investigate whether deep learning-based body weight from chest CT scout images can be an alternative to actual body weight in CT radiation dose management. Chest CT scout images and diagnostic images acquired for medical checkups were collected from 3601 patients. A deep learning model was developed to predict body weight from scout images. The correlation between actual and predicted body weight was analyzed. To validate the use of predicted body weight in radiation dose management, the volume CT dose index (CTDIvol ) and the dose-length product (DLP) were compared between the body weight subgroups based on actual and predicted body weight. Surrogate size-specific dose estimates (SSDEs) acquired from actual and predicted body weight were compared to the reference standard. The median actual and predicted body weight were 64.1 (interquartile range: 56.5-72.4) and 64.0 (56.3-72.2) kg, respectively. There was a strong correlation between actual and predicted body weight (ρ=0.892, p<0.001). The CTDIvol and DLP of the body weight subgroups were similar based on actual and predicted body weight (p<0.001). Both surrogate SSDEs based on actual and predicted body weight were not significantly different from the reference standard (p=0.447 and 0.410, respectively). Predicted body weight can be an alternative to actual body weight in managing dose metrics and simplifying SSDE calculation. Our proposed method can be useful for CT radiation dose management in adult patients with unknown body weight.

Reducing contrast-agent volume and radiation dose in CT with 90-kVp tube voltage, high tube current modulation, and advanced iteration algorithm.

Increasing utilization of computed tomography (CT) has raised concerns regarding CT radiation dose and technology has been developed to achieve an appropriate balance between image quality, radiation dose, and the amount of contrast material. This study was planned to evaluate the image quality and radiation dose in pancreatic dynamic computed tomography (PDCT) with 90-kVp tube voltage and reduction of the standard amount of contrast agent, compared with 100-kVp PDCT of the research hospital's convention. Total of 51 patients with both CT protocols were included. The average Hounsfield units (HU) values of the abdominal organs and image noise were measured for objective image quality analysis. Two radiologists evaluated five categories of image qualities such as subjective image noise, visibility of small structure, beam hardening or streak artifact, lesion conspicuity and overall diagnostic performance for subjective image quality analysis. The total amount of contrast agent, radiation dose, and image noise decreased in the low-kVp group, by 24.4%, 31.7%, and 20.6%, respectively (p < 0.001). The intraobserver and interobserver agreements were moderate to substantial (k = 0.4-0.8). The contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and figure of merit of the almost organs except psoas muscle in the low-kVp group were significantly higher (p < 0.001). Except for lesion conspicuity, both reviewers judged that subjective image quality of the 90-kVp group was better (p < 0.001). With 90-kVp tube voltage, 25% reduced contrast agent volume with advanced iteration algorithm and high tube current modulation achieved radiation dose reduction of 31.7%, as well as better image quality and diagnostic confidence.

Radiation Dose Management in Computed Tomography: Introduction to the Practice at a Single Facility.

Although the clinical benefits of computed tomography (CT) are undoubtedly high, radiation doses received by patients are also relatively high; therefore, radiation dose management is mandatory to optimize CT radiation doses and prevent excessive radiation events. This article describes CT dose management practice at a single facility. Many imaging protocols are used in CT depending on the clinical indications, scan region, and CT scanner; thus, managing the protocols is the first step for optimization. The appropriateness of the radiation dose for each protocol and scanner is verified, while answering whether the dose is the minimum to obtain diagnostic-quality images. Moreover, examinations with exceptionally high doses are identified, and the cause and clinical validity of the high dose are assessed. Daily imaging practice should follow standardized procedures, avoiding operator-dependent errors, and information required for radiation dose management should be recorded at each examination. The imaging protocols and procedures are reviewed for continuous improvement based on regular dose analysis and multidisciplinary team collaboration. The participation of many staff members in the dose management process is expected to contribute to promoting radiation safety through increased staff awareness.