Computed Tomography Dose Research Articles

Advancing pediatric head CT dose prediction: correlating patient size metrics with AP and LAT dimensions in Moroccan population

This study aims to establish comprehensive relationships between patient size, focusing on effective diameter (Deff) and water-equivalent diameter (Dw), in conjunction with anterior-posterior (AP) and lateral (LAT) dimensions. The primary goal is to refine precise patient dose estimations in pediatric head computed tomography (CT) examinations. Our examination involved a dataset of 105 pediatric head CT images sourced from a Moroccan pediatric university hospital. These images, selected from the central scanning range, underwent quantification for LAT, AP, Deff, and Dw, with measurements carried out using RadiAnt Dicom Viewer for lateral and anteroposterior dimensions. Our analytical approach encompassed modeling Deff and Dw as functions of LAT, AP, and combined AP + LAT dimensions. Additionally, Dw was modeled as a function of Deff and calculated Size Specific Dose Estimates (SSDE) based on Dw was compared to SSDE computed from one single dimension. The outcomes revealed strong correlations among Deff, Dw, and fundamental geometric dimensions (LAT, AP, and AP + LAT), as indicated by consistently high coefficients of determination (R² > 0.8). SSDE calculated from Dw shows impressive correlation with SSDE computed from a single dimension (R² > 0.9). This study offers insights into the relationships between patient size and critical dimensions, identifying high correlations that can represent a significant advancement in predicting doses for pediatric head CT examinations. This introduces the potential for streamlining the determination of head diameter and dose by relying on a single dimension, thereby enhancing the efficiency of dose predictions by facilitating the monitoring of radiation exposure of this population in clinical routine.

Comparing Radiation Doses in CBCT and Medical CT Imaging for Dental Applications.

Dental imaging plays a crucial role in diagnosis and treatment planning, with cone-beam computed tomography (CBCT) and medical computed tomography (CT) being two common modalities. This study aims to compare the radiation doses associated with CBCT and medical CT imaging in dental applications to assess their relative safety and efficacy. We conducted a retrospective study using data from 100 patients who underwent both CBCT and medical CT scans for dental purposes. The radiation doses were measured in terms of dose-length product (DLP) for medical CT and dose-area product (DAP) for CBCT. The effective dose (ED) was calculated using appropriate conversion factors. Patient demographics, scan parameters, and radiation doses were recorded and analyzed. The results indicated that the mean DLP for medical CT scans was 220 mGycm, whereas the mean DAP for CBCT scans was 150 mGycm². The corresponding mean effective doses for medical CT and CBCT were 2.5 mSv and 1.8 mSv, respectively. The radiation dose from CBCT was found to be approximately 28% lower than that from medical CT. This study demonstrates that CBCT imaging for dental applications results in significantly lower radiation doses compared to medical CT. While both modalities provide valuable diagnostic information, the choice of imaging technique should consider the balance between diagnostic quality and radiation exposure, especially for pediatric and high-risk patients. Dental practitioners should be aware of the potential dose reduction benefits associated with CBCT when appropriate for the clinical scenario.

Weighted CTDI Equation for 3D Rotational Angiography: A Monte Carlo Study

This study aims to verify the weighted Computed Tomography Dose Index (CTDIw) coefficients of 3D rotational angiography (3DRA) procedure using Monte Carlo simulation. The Monte Carlo simulation EGSnrc usercode was employed for 3D dose simulations of the rotational angiography procedure. A virtual phantom resembles the head CTDI phantom was constructed, with a diameter of 16 cm and a density resembling polymethyl methacrylate (1.13 g/cm3). A series of virtual phantoms consisting of 5 images with ionization chamber detectors at the center position, 12 o'clock, 9 o'clock, 6 o'clock, and 3 o'clock were acquired. Simulations were performed with photon sources of 70 and 109 kVp for 200-degree x-ray tube rotation. The field of view was divided into narrow, wide, and full beam with diameters of 1.7 cm; 4.9 cm; and 8.6 cm, respectively. The simulated doses at the ionization chamber were processed into weighting factor for weighted CTDI and compared with direct measurements. The dose ratio between peripheral and center positions for 360° CBCT and 200° 3DRA was 1:1 and 1:3 in this study. The weighting factors for 3DRA were determined as CTDIcenter = ¼ and CTDIperiphery = ¾. The measured average percentage difference of CTDIw between our weighted factor and conventional CTDIw was 1.75 % (-3.99 % to 6.08 %). The x-ray tube position of 3DRA impacted the accuracy of weighting factor of CTDIw, with implications for the proposed weighting factor (Wcenter = ¼ and Wperiphery = ¾) when using a 3DRA machine.

Performance evaluation of computed tomography scanners in Indonesia: recommendation from a nation-wide study.

In this study, an evaluation of the compliance test data from 684 computed tomography (CT)-scanners in Indonesia for the 2019-22 test period was carried out. The study was aimed to describe the performance profile of CT-scanners in Indonesia and evaluate the testing protocol. A total of 87.8% of the CT-scanners unconditionally passed the tests, 8.8% passed the tests with conditions and 3.4% failed the tests. Of the devices conditionally passed the tests, the top two causes were water CT number accuracy (45.2%) and laser position accuracy (41.9%). Meanwhile, 75.0% of the failed devices were due to failing to meet the patient dose test criteria. The failure of the test for the water CT number accuracy parameter was caused by variations in the type of phantom used in the test, where several types of phantoms did not use water as material of the homogeneity module. Failures in laser position accuracy test were caused by the passing criteria that adjust to the minimum slice thickness, so that modern CT-scanner with small detector sizes and collimations tend not to pass. On the other hand, the failure on dose aspects was due to the frequent unavailability of baseline values for comparison. Of these top three failure causes, two of them, namely the CT number and dose test parameters, have been accommodated in the latest regulation (BAPETEN Regulation No. 2/2022) with a change in the evaluation method, while for the laser position accuracy test it is recommended to alter the passing criteria to an absolute value, namely 1mm.

Assessing the influence of X-ray spectrum on image quality in abdominal computed tomography scans

This work aims to evaluate the effect of acquisition parameters of the abdominal computed tomography protocol on image quality and dose, including the contrast-to-noise ratio (CNR), noise, spatial resolution (SR) as well as volumetric computed tomography dose index (CTDIvol). The measurements have been performed on a 16-slice HITACHI scanner using the polymethylmethacrylate phantom for CTDIvol and Catphan 500 for image quality. Two tube voltages of 120 kVp and 100 kVp have been analyzed while varying the tube current settings from 100 to 300 (mA) to measure image quality quantities and dose (CTDIvol). The scanning with 100 kVp compared to 120 kVp has led to a dose reduction up to 38% at mAs ranging from 100 to 300, a decrease in CNR by 28%, with a slight decrease in spatial resolution accompanied by an increase in noise. This work has shown that despite the increase in noise at 100 kVp, it is possible to reduce the dose without affecting the quantities of spatial resolution and the contrast/noise ratio by lowering the tube voltage from 120 kVp to 100 kVp.

Optimization of Routine Pediatric Computed Tomography Examinations in Hawassa City, Sidama Regional State, Ethiopia

Computed tomography (CT) has considerable impact in patient care. However, it is the most irradiating medical imaging technique in diagnostic radiology department. Optimization of pediatric CT is not well-practiced in developing countries. Protocols for some age groups were missed, and scan parameters are not adapted to the patient body size and age group. Furthermore, there are no established diagnostic reference levels to enhance dose optimization for pediatric patients at the local, regional, and national levels. Therefore, this study aimed to assess the optimization of routine pediatric CT examinations in Hawassa city, Ethiopia. A total of 360 pediatric dose records were reviewed for routine pediatric CT performed between January 1st, 2021 - May 30th, 2022. The data were analyzed using the statistical package for social science version 25 software. The Local Diagnostic Reference Levels (LDRLs) were established at the 75th percentile of CT dose quantities. The average KVp, mAs, and scan length used for pediatric head, chest, and abdomen CT were (112.8, 260.6, and 19.8), (112.9, 64.7, and 31.5), and (113.3, 79.4, and 32.9) respectively. The range of the established LDRLs in terms of volumetric CT dose index for the head, chest, and abdomen CT were (31.5 to 47, 2.3 to 6.1, 1.7 to 4.7) mGy. Whereas the range in terms of dose length product per scan for the head, chest, and abdomen CT were (723.4 to 1126.7, 55.9 to 258.9, and 38.1 to 242.5) mGy cm respectively. The obtained results show that the LDRLs for volumetric CT does index for head and chest CT were equivalent to the international studies. Whereas the local DRLs in terms of dose length product per scan were higher than the reports other studies except in Japan where the values for chest CT were comparable to the results of this study. Finally, the findings suggested that non-optimized pediatric head and chest CT were performed across all age groups.

Study of Low kV, Low Contrast Agent Dosage, and Low Contrast Agent Flow Rate Scan in Computed Tomography Angiography of Children's Liver

Background: During computed tomography (CT) examinations, the presence of radiation material undoubtedly has a certain impact on patients, particularly children, who are more susceptible to radiation. Consequently, finding ways to minimize radiation dosage and mitigate radiation-related risks while enhancing the quality and accuracy of CT scans has become a crucial concern for medical professionals in CT equipment manufacturing companies and radiology departments to contemplate. Objectives: This study aimed to explore the feasibility of low dose and low contrast medium combined with low flow rate scanning in CT angiography (CTA) of children's liver. Patients and Methods: A total of 59 children who visited our department for liver vascular CT scans between April 2021 and December 2022 were prospectively selected and randomly divided into 2 groups: the experimental group and the control group. The experimental group consisted of 28 children who received an injection of 80 kV, automatic tube current, low contrast dose (1.5 mL/kg), and low flow rate of 20 s. The control group included 31 children who were injected with 100 kV, automatic tube current, contrast agent dose (2 mL/kg), and flow rate of 16 s. The objective and subjective image quality, radiation dose, and iodine intake in the arterial, portal, and venous phases were compared between the 2 groups. Results: During the arterial, portal, and venous phases, the experimental group exhibited lower signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) compared to the control group (P < 0.05). However, there was no significant difference in subjective quality scores between the 2 groups (P > 0.05). The effective dose (ED), volume CT dose index (CTDIvol), and dose-length product (DLP) of the experimental group were lower than those of the control group (P < 0.05). Additionally, the iodine intake in the experimental group was lower than that in the control group (P < 0.05). Conclusion: In the examination of hepatic vascular CTA in children, the use of a 3-low scanning technique can effectively decrease radiation and contrast agents while ensuring sufficient image quality for accurate clinical diagnosis.

Exploring the Low-Dose Limit for Focal Hepatic Lesion Detection with a Deep Learning-Based CT Reconstruction Algorithm: A Simulation Study on Patient Images.

This study aims to investigate the maximum achievable dose reduction for applying a new deep learning-based reconstruction algorithm, namely the artificial intelligence iterative reconstruction (AIIR), in computed tomography (CT) for hepatic lesion detection. A total of 40 patients with 98 clinically confirmed hepatic lesions were retrospectively included. The mean volume CT dose index was 13.66 ± 1.73 mGy in routine-dose portal venous CT examinations, where the images were originally obtained with hybrid iterative reconstruction (HIR). Low-dose simulations were performed in projection domain for 40%-, 20%-, and 10%-dose levels, followed by reconstruction using both HIR and AIIR. Two radiologists were asked to detect hepatic lesion on each set of low-dose image in separate sessions. Qualitative metrics including lesion conspicuity, diagnostic confidence, and overall image quality were evaluated using a 5-point scale. The contrast-to-noise ratio (CNR) for lesion was also calculated for quantitative assessment. The lesion CNR on AIIR at reduced doses were significantly higher than that on routine-dose HIR (all p < 0.05). Lower qualitative image quality was observed as the radiation dose reduced, while there were no significant differences between 40%-dose AIIR and routine-dose HIR images. The lesion detection rate was 100%, 98% (96/98), and 73.5% (72/98) on 40%-, 20%-, and 10%-dose AIIR, respectively, whereas it was 98% (96/98), 73.5% (72/98), and 40% (39/98) on the corresponding low-dose HIR, respectively. AIIR outperformed HIR in simulated low-dose CT examinations of the liver. The use of AIIR allows up to 60% dose reduction for lesion detection while maintaining comparable image quality to routine-dose HIR.

Local Diagnostic Reference Levels for Adult Computed Tomography Urography Exams.

A Computed Tomography Urography (CTU) scan is a medical imaging test that examines the urinary tract, including the bladder, kidneys, and ureters. It helps diagnose various urinary tract diseases with precision. However, patients undergoing CTU imaging receive a relatively high dose of radiation, which can be a concern. In our research paper, we analyzed the Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP) for 203 adult patients who underwent CTU at one of the most important regional centers in Bosnia and Herzegovina that sees a large number of patients. Our study included the distribution of age and sex, the number of phases within one examination, and different clinical indications. We compared our findings with the results available in the scientific literature, particularly the recently published results from 20 European countries. Furthermore, we established the local diagnostic reference levels (LDRLs) that can help set the national diagnostic reference levels (NDRLs). We believe our research is a significant step towards optimizing the protocols used in different hospitals in our country.

A model for estimating peak skin dose in CT.

In interventional radiology patient care can be improved by accurately assessing peak skin dose (PSD) from procedures, as it is the main predictor for tissue-reactions such as erythema. Historically, high skin dose procedures performed in radiology departments were almost exclusively planar fluoroscopy. However, with the increase in use of technologies involving repeated or adjacent computed tomography (CT) such as CT fluoroscopy and multi-modality rooms, the peak skin dose delivered by CT needs to be considered. In this paper, a model to estimate the PSD delivered to a patient undergoing CT has been developed to assist in determining the overall PSD. This model relates the PSD to the device-reported CT Dose Index (CTDIvol) by accounting for a variety of CT technique and patient factors. It includes a novel method for estimating dose contributions as a function of patient or phantom size, scanner geometry, and physical measurement of lateral and depth-based beam profiles. Physical measurements of PSD using radiochromic film on several phantoms have been used to determine needed model parameters. The resulting fitted model was found to agree with measured data to a standard deviation of 5.1% for the data used to fit the model, and 6.8% for measurements that were not used for fitting the model. Two methods for adapting the model for specific scanners are provided, one based on local PSD measurements with radiochromic film and another using CTDIvol measurements. The model, when suitably adapted, can accurately assess individual patients' CT PSD. This information can be integrated with radiation exposure data from other modalities, such as planar fluoroscopy, to predict the overall risk of tissue reactions, allowing for more tailored patient care.

Redefining Radiation Metrics: Evaluating Actual Doses in Computed Tomography Scans.

Computed tomography (CT) contributes significantly to the collective dose from medical sources, raising concerns about potential health risks. However, existing radiation dose estimation tools, such as volume computed tomography dose index (CTDIvol), dose-length product (DLP), effective dose (ED), and size-specific dose estimate (SSDE), have limitations in accurately reflecting patient exposure. This study introduces a new parameter, size-specific dose-length product (DLPss), aiming to enhance the precision of radiation dose estimation in real-life scenarios. A retrospective analysis of 134 chest CT studies was conducted. Relationships between CTDIvol and anthropometric parameters were examined, and SSDE was calculated based on effective diameter. Additionally, the novel parameter, DLPss, was introduced, considering scan length and cross-sectional dimensions. Analysis reveals variations in scan length, effective diameter, and CTDIvol between genders. Strong correlations were observed between CTDIvol and effective diameter, particularly in men. The average CTDIvol for the entire group was 7.83 ± 2.92 mGy, with statistically significant differences between women (7.38 ± 3.23 mGy) and men (8.30 ± 2.49 mGy). SSDE values showed significant gender differences, with men exhibiting higher values. The average SSDE values for women and men were 9.15 ± 2.5 mGy and 9.6 ± 2.09 mGy, respectively, with a statistically significant difference (p = 0.03). The newly introduced DLPss values ranged around 343.90 ± 81.66 mGy·cm for the entire group, with statistically significant differences between women (323.53 ± 78.69 mGy·cm) and men (364.89 ± 79.87 mGy·cm) (p < 0.05), providing a comprehensive assessment of total radiation dose. The study highlights the need for accurate radiation dose estimation, emphasizing the impact of CT examination parameters on dose variability. The proposed DLPss parameter offers a promising approach to enhancing precision in assessing radiation risk during CT scans. Further research is warranted to explore additional parameters for a comprehensive understanding of radiation exposure and to optimize imaging protocols for patient safety.

Establishment and utilisation of national diagnostic reference level for adult computed tomography examinations in Ghana.

The International Atomic Energy Agency, as part of the new regional project (RAF/9/059), recommend the establishment of diagnostic reference levels (DRLs) in Africa. In response to this recommendation, this project was designed to establish and utilise national DRLs of routine computed tomography (CT) examinations. These were done by estimating CT dose index and dose length product (DLP) from a minimum of 20 patient dose report of the most frequently used procedures using 75th percentile distribution of the median values. In all, 22 centres that formed 54% of all CT equipment in the country took part in this study. Additionally, a total of 2156 adult patients dose report were randomly selected, with a percentage distribution of 60, 12, 21 and 7% for head, chest, abdomen-pelvis and lumber spine, respectively. The established DRL for volume CT dose index were 60.0, 15.7, 20.5 and 23.8mGy for head, chest, abdomen-pelvis and lumber spine, respectively. While the established DRL for DLP were 962.9, 1102.8, 1393.5 and 824.6mGy-cm for head, chest, abdomen-pelvis, and lumber spine, respectively. These preliminary results were comparable with data from 16 other African countries, European Commission and the International Commission on Radiological Protection. Hence, this study would serve as a baseline for the establishment of a more generalised regional and national adult DRLs for Africa and other developing countries.

A CT deep learning reconstruction algorithm: Image quality evaluation for brain protocol at decreasing dose indexes in comparison with FBP and statistical iterative reconstruction algorithms

PurposeTo characterise the impact of Precise Image (PI) deep learning reconstruction algorithm on image quality, compared to filtered back-projection (FBP) and iDose4 iterative reconstruction for brain computed tomography (CT) phantom images. MethodsCatphan-600 phantom was acquired with an Incisive CT scanner using a dedicated brain protocol, at six different dose levels (volume computed tomography dose index (CTDIvol): 7/14/29/49/56/67 mGy). Images were reconstructed using FBP, levels 2/5 of iDose4, and PI algorithm (Sharper/Sharp/Standard/Smooth/Smoother). Image quality was assessed by evaluating CT numbers, image histograms, noise, image non-uniformity (NU), noise power spectrum, target transfer function, and detectability index. ResultsThe five PI levels did not significantly affect the mean CT number. For a given CTDIvol using Sharper-to-Smoother levels, the spatial resolution for all the investigated materials and the detectability index increased while the noise magnitude decreased, slightly affecting noise texture. For a fixed PI level increasing the CTDIvol the detectability index increased, the noise magnitude decreased. From 29 mGy, NU values converged within 1 Hounsfield Unit from each other without a substantial improvement at higher CTDIvol values. ConclusionsThe improved performances of intermediate PI levels in brain protocols compared to conventional algorithms seem to suggest a potential reduction of CTDIvol.

Institutional clinical indication-based typical dose values of multiphasic abdominopelvic computed tomography examinations.

Our study aimed to obtain clinical indication-based typical dose values and size-specific dose estimates (SSDEs) for multiphasic abdominopelvic computed tomography (CT) examinations and to review our data with published diagnostic reference levels (DRLs). In this retrospective study, multiphasic liver, kidney, pancreas, and mesenteric ischemia protocol CT scans performed at our center between January 2018 and December 2021 were analyzed. The clinical indications were hepatocellular carcinoma, renal cell carcinoma, pancreas adenocarcinoma, and mesenteric ischemia. The computed tomography dose index volume (CTDIvol) and dose-length product (DLP) values were recorded, and the SSDE and effective dose (ED) values were calculated. The water-equivalent diameter (Dw) value required for the SSDE calculation was measured using the automated calculation of the Dw program. The total number of patients was 514, with 86 patients excluded from this study. The dose values were calculated for 426 patients (183 female and 243 male; 111 liver, 120 kidney, 85 pancreas, and 110 mesenteric). The median values for the CTDIvol, DLP, SSDE, and ED were 6.86 mGy, 683.02 mGy. cm, 8.75 mGy, and 10.45 mSv for the liver CT; 8.37 mGy, 908.37 mGy.cm, 10.37 mGy, and 13.89 mSv for the kidney CT; 7.82 mGy, 517.98 mGy.cm, 10.01 mGy, and 7.92 mSv for the pancreas CT; and 9.48 mGy, 983.68 mGy.cm, 12.78 mGy, and 13.86 mSv for the mesenteric CT, respectively. All dose values were lower than the published DRLs. The literature reveals large differences in the multiphasic abdominopelvic CT protocols, especially in the number of phases and scan length. This situation makes comparing dose values difficult. Dose studies revealing the protocol parameters in detail are needed so that institutions can compare and optimize their own protocols. Additionally, users should periodically check the dose values in their own institutions.

Establishment of local diagnostic reference levels for CT colonography at a tertiary hospital.

Diagnostic reference levels (DRLs) are an important metric in identifying abnormally high radiation doses in diagnostic examinations. National DRLs for CT colonography do not currently exist in South Africa, but there are efforts to collect data for a national DRL project. This study investigated radiation doses for CT colonography in adult patients at a large tertiary hospital in South Africa with the aim of setting local DRLs. Patient data from two CT scanners (Philips Ingenuity and Siemens Somatom go.Top) in the period March 2020 - March 2023 were obtained from the hospital's picture archiving and communication system (PACS) (n = 115). Analysis involved determining the median computed tomography dose index-volume (CTDIvol) and dose-length product (DLP) values. The findings were compared with DRLs established internationally. Ingenuity median CTDIvol was 20 mGy and DLP was 2169 mGy*cm; Somatom median CTDIvol was 6 mGy and DLP was 557 mGy*cm. Ingenuity exceeded the United Kingdom's (UK) recommended DRLs by 82% and 214%, respectively. Somatom median CTDIvol and DLP were 45% and 19% lower than UK NDRLs. Somatom's tin filter and other dose reduction features provided significant dose reduction. These data were used to set DRLs for CT colonography at the hospital; CTDIvol: 6 mGy and DLP: 557 mGy*cm. In addition to informing radiation protection practices at the level of the institution, the established local DRLs contribute towards implementing regional and national DRLs.

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.

PAE planning: Radiation exposure and image quality of CT and CBCT

PurposeTo determine accurate organ doses, effective doses, and image quality of computed tomography (CT) compared with cone beam CT (CBCT) for correct identification of prostatic arteries. MethodA dual-energy CT scanner and a flat-panel angiography system were used. Dose measurements (gallbladder (g), intestine (i), bladder (b), prostate (p), testes (t), active bone marrow of pelvis (bmp) and femura (bmf)) were performed using an anthropomorphic phantom with 65 thermoluminescent dosimeters in the pelvis and abdomen region. For the calculation of the contrast-to-noise ratio (CNR) of the pelvic arteries, a patient whose weight and height were almost identical to those of the phantom was selected for each examination type. ResultsThe effective dose of CT was 2.7 mSv and that of CBCT was 21.8 mSv. Phantom organ doses were lower for CT than for CBCT in all organs except the testes (g: 1.2 mGy vs. 3.3 mGy, i: 5.8 mGy vs. 23.9 mGy, b: 6.9 mGy vs. 19.4 mGy, p: 6.4 mGy vs. 13.2 mGy, t: 4.7 mGy vs. 2.4 mGy, bmp: 5.1 mGy vs. 18.2 mGy, bmf: 3.3 mGy vs. 6.6 mGy). For human pelvic arteries, the CNR of CT was better than that of CBCT, with the exception of one prostate artery that showed stenosis on CT. Evaluation by experienced radiologists also confirmed the better detectability of prostate arteries on CT examination. ConclusionsIn our study preprocedural CT had lower organ doses and better image quality comparedd with CBCT and should be considered for the correct identification of prostatic arteries.

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.

Estimation and comparison of the effective dose and lifetime attributable risk of thyroid cancer between males and females in routine head computed tomography scans: a multicentre study.

A significant number of head computed tomography (CT) scans are performed annually. However, due to the close proximity of the thyroid gland to the radiation field, this procedure can expose the gland to ionising radiation. Consequently, this study aimed to estimate organ dose, effective dose (ED) and lifetime attributable risk (LAR) of thyroid cancer from head CT scans in adults. Head CT scans of 74 patients (38 males and 36 females) were collected using three different CT scanners. Age, sex, and scanning parameters, including scan length, tube current-time product (mAs), pitch, CT dose index, and dose-length product (DLP) were collected. CT-Expo software was used to calculate thyroid dose and ED for each patient based on scan parameters. LARs were subsequently computed using the methodology presented in the Biologic Effects of Ionizing Radiation (BEIR) Phase VII report. Although the mean thyroid organ dose (2.66 ± 1.03 mGy) and ED (1.6 ± 0.4 mSv) were slightly higher in females, these differences were not statistically significant compared to males (mean thyroid dose, 2.52 ± 1.31 mGy; mean ED, 1.5 ± 0.4 mSv). Conversely, there was a significant difference between the mean thyroid LAR of females (0.91 ± 1.35) and males (0.20136 ± 0.29) (P = 0.001). However, the influencing parameters were virtually identical for both groups. The study's results indicate that females have a higher LAR than males, which can be attributed to higher radiation sensitivity of the thyroid in females. Thus, additional care in the choice of scan parameters and irradiated scan field for female patients is recommended.

Analysis of Computed Tomography Dose Index (CTDI) And Dose Length Product (DLP) Dose Values On Non-Contrast Head, Chest And Abdominal CT Scan Examination At RSUD Ulin Banjarmasin

Background: CT scans produce the largest dose of radiation compared to other radiology modalities. The parameters for measuring the amount of radiation dose from the CT Scan aircraft are the Computed Tomography Dose Index (CTDI) and the Dose Lenght Product (DLP). One form of Bapeten supervision in controlling radiation protection is to optimize the Diagnostic Raference Level (DRL). At RSUD Ulin Banjarmasin, the CT Scan modality has never been measured for CT Scan dose on CT Scan examination of the Head, Thorax and Abdomen Non Contrast which are the most frequent examinations. Dosage parameters are important to see the values exposed to the patient. The purpose of this study was to determine the amount of radiation dose of patients on CT Scan examination of the Head, Thorax and Non-Contrasting Abdomen. Method: The research design used is quantitative descriptive. The method of collecting data is observational and uses secondary data. Data processing uses the descriptive hypothesis test method one sample t-test, by analyzing the value of radiation dose and comparing the DRL value set by Bapeten as a means to monitor the dose given α=0.05. Results: Dose values for CT Scan of Non Contrast Head 33.90±3.66 mGy for CTDIvol and 933.07±415.63 mGy.cm for DLP. CT Scan Thorax Non Contrast 5.83±1.90 mGy for CTDIvol and 179.80±63.72 mGy.cm for DLP. Non Contrast Abdominal CT Scan 10.88±2.30 mGy for CTDIvol and 528.70±137.75 mGy.cm for DLP. Conclusion: The dose value at RSUD Ulin Banjarmasin in each CT Scan examination of the Head, Thorax and Abdomen Non Contrast is still below the National DRL value set by BAPETEN.