Dose-length Product Research Articles

Comparative study on Various Tube Voltages and Contrast Media Doses in CT Pulmonary Angiography to detect Pulmonary Thromboembolism

Background: Lowering the amount of iodinated contrast material and tube voltage may increase pulmonary artery opacification and thrombus identification without compromising picture quality. Objectives: To explore the efficiency of using lower tube voltage and a lower contrast medium dose for conducting computed tomography for pulmonary angiography (CTPA) aiming to increase its accuracy in detecting pulmonary thromboembolism (PTE). Subjects and Methods:100 patients scheduled for CTPA with a preoperative diagnosis of PTE were grouped into two: group A, (50 patients) got 1 mL/kg at 120 kV and group B, (50 patients) received 0.5 mL/kg at 80 kV.The technique of bolus tracking was implemented.Values of midpoint of multiple pulmonary artery divisions were used to assess attenuation.Significant values are those that exceed 300 Hounsfield units (HU). The dosage of radiation received by the patient, defined as the effective dose, was compared between groups. Results: Total mean attenuationdata for the pulmonary arteries have shown to be substantially greater in group-B compared to group-A (39110.4HU vs. 335.97.9HU, P=0.001). Moreover, total dose length product (DLP) values were substantially lower in group-B (934.9 mGy.cm vs. 384.443 mGy.cm, P=0.001). While effective dose values have shown to be significantly lower in group-B (2.90.3 mSv vs. 13.21.8 mSv, P 0.001). Conclusion: Low-kilovoltage technique and low quantity of iodinated contrast are useful in conducting (CTPA) with high accuracy in detection of pulmonary thromboembolism.

Comparison of image quality and pancreatic ductal adenocarcinoma conspicuity between the low-kVp and dual-energy CT reconstructed with deep-learning image reconstruction algorithm

PurposeTo compare the image quality and conspicuity of pancreatic ductal adenocarcinoma (PDAC) between the low-kVp and dual-energy pancreatic protocol CT reconstructed with deep-learning image reconstruction (DLIR). MethodA cohort of 111 consecutive patients (median age, 72 years; 56 men) undergoing a pancreatic protocol CT were retrospectively analyzed. Among them, 58 patients underwent 80-kVp CT (80-kVp group), and 53 patients underwent dual-energy CT and reconstructed at 40-keV (40-keV group). The medium-strength level of DLIR were used in both groups. Quantitative measurements, qualitative image quality, PDAC conspicuity, and dose-length product (DLP) were compared between the two groups using Mann–Whitney U test. ResultsA total of 20 and 16 PDACs were found in the 80-kVp and 40-keV groups, respectively. CT numbers of the vasculatures and parenchymal organs (P <.001 for all) and the background noise at both pancreatic and portal venous phases (P <.001) were higher in the 40-keV group than in the 80-kVp group. The signal-to-noise ratio (SNR) of all anatomical structures (P <.001–0.005), except for the liver in reviewer 2 (P =.47), and the tumor-to-pancreas contrast-to-noise ratio (CNR; P <.001–0.01) were higher in the 40-keV group than in the 80-kVp group. No difference was found in the image quality at both phases (P =.30–0.90). PDAC conspicuity was better in the 40-keV group than in the 80-kVp group (P =.007–0.03). DLP at pancreatic (275 vs. 313 mGy*cm; P =.05) and portal venous phases (743 vs. 766 mGy*cm; P =.20) was comparable between the two groups. ConclusionUnder the same DLP, virtual monoenergetic images at 40-keV demonstrated higher SNR and tumor-to-pancreas CNR and better PDAC conspicuity compared to the 80-kVp setting.

Cancer risk in healthy patients who underwent chest tomography comparing three different technologies

This research aimed to estimate the risk of cancer associated with patients without previous disease undergoing chest tomography. Siemens CT scanners have 6, 64, and 128 detectors. The Biologic Effects of Ionizing Radiation Reports - BEIR VII methodology was used. The study presented a sample of 64 patients aged between 18 and 80 years, in the city of Belo Horizonte, Minas Gerais - Brazil. The IMPACT CT software and CalDose X CT Online were used to calculate the absorbed and equivalent dose from the Volumetric Computed Tomography Dose Index - CTDIvol (mGy) and Dose Length Product - DLP values provided by the equipment. CT-Expo Software was also used to estimate Specific Dose Estimates (SSDEs) values. The CTDvol results for the MG1, MG,2 and MG3 Diagnostic Centers in mGy were respectively 4.369 ± 1.352, 6.99 4 ± 1.53,3 and 9.984 ± 2.282 and the SSDE values were 3.800, 6.40,0 and 9,.500. The values for the equivalent dose, at the MG2 Diagnostic Center, by IMPACT CT, in (mSv) for the breasts, esophagus, heart, thyroid, lung and thymus were respectively 3.9, 5.7, 4.7, 1.0, 4.8 and 5.7. The CalDose Software, for the same equipment and the same organs, in mSv, estimated the values 7.4, 9.4, 11.1, 5.3, 10.8 and 11.3 for women and 7.1, 9.3, 11.0, 5.3, 10.2 and 10.9 for men. The estimated risk of cancer decreased according to the patient's age, but with a higher incidence for females. The use of each software must be carefully analyzed to avoid undue values due to the particularities of each one. The results also showed that the risk of developing cancer due to radiation decreases with patient age and is higher in females.

APPLICATION OF CT PULMONARY ANGIOGRAPHY WITH "ULTRA-DOUBLE-LOW" AND ITERATIVE MODEL RECONSTRUCTION FOR ACUTE PULMONARY EMBOLISM.

The study is to investigate the feasibility of computed tomography pulmonary angiography (CTPA) with iterative model reconstruction (IMR) and "Ultra-double-low" (Ultra-low dose, Ultra-low contrast agent volume). Thirty-six patients who tested positive for pulmonary embolism in CTPA were enrolled in the study. Another CTPA was performed 1 week after thrombolytic therapy. The first examination was routine CTPA (Routine Group) with the parameters as follows: automatic mA scanning, 120kV and image reconstruction by using iDose4 iterative reconstruction (Lever 4), iodine concentration and dose of contrast agent: 300mgI/ml and 0.5gI/kg, respectively. The latter one was ultra-low dose CTPA examination (Ultra-low Group): 40 mAs, 80kV and IMR (Lever 3), contrast agent: 300mgI/ml and 15mL, respectively. Effective dose (ED), CT dose index volume (CTDIvol), dose length product (DLP), attenuation of pulmonary artery, contrast noise ratio (CNR) and signal noise ratio (SNR) were recorded and calculated. The imaging qualities were subjectively assessed. The Eds/CTDIvols/DLPs of Ultra-low Group are lower than the Routine Group (P<0.05). The differences in attenuation between the two groups are not significant (P>0.05). The differences in CNR and SNR between the two groups are significant (P<0.05). The differences in imaging qualities between the two groups when subjectively assessed are not significant (P>0.05). The 256-slice spiral CT combined with IMR and "Ultra-double-low" is feasible for the acute pulmonary embolism examination and the radiation dose and the volume of contrast agent can be greatly reduced.

Utilization of computed tomography in pediatric temporal fractures: A dose reduction approach

Objectives1)Determine the sensitivity and specificity of CT brain to detect temporal bone fractures.2)Calculate the additional ionizing radiation exposure incurred from a TBCT. MethodsRetrospective chart review was performed of pediatric patients who underwent CT brain as part of a trauma pan-scan and dedicated temporal bone CT in the setting of head trauma. The original CT images were re-reviewed by two board certified Neuroradiologists in a blinded manner to determine the presence or absence of temporal bone fracture and if present, fracture line involvement of the 5 critical temporal bone anatomic structures. The dose length product (DLP), a measure of approximate total radiation dose delivered during CT scan (mGy-cm), was noted from the data available. ResultsThere were 24 temporal bone fractures in a total of 29 patients (4 with bilateral fractures). There were 21 of 24 fractures that were correctly identified on trauma pan-scan CT with dedicated temporal bone CT considered as the diagnostic gold standard. There was a combined sensitivity and specificity of 91 % and 100 % respectively. The sensitivity and specificity in identifying involvement of critical structures were as follows: carotid canal (100 % and 100 %); ossicular chain (75 % and 100 %); tegmen tympani (60 % and 97.9 %); facial nerve canal (25 % and 100 %); otic capsule (N/A and 98.5 %). The median DLP for trauma pan-scan CT and temporal bone CT were 627 mGy-cm and 267 mGy-cm respectively. ConclusionDedicated TBCT is not required to accurately diagnose and characterize temporal bone fractures seen on trauma pan-scan CT. The radiation exposure of concurrent or subsequent dedicated temporal bone imaging is equal to approximately one half of the original trauma pan-scan CT.

DEVELOPING DIAGNOSTIC REFERENCE LEVELS FOR CT EXAMINATIONS IN ADDIS ABABA, ETHIOPIA.

Diagnostic reference level (DRL) is an appropriate instrument toward promoting radiation doses optimisation in medical imaging. The goal of this research is developing DRL to optimise computed tomography (CT) doses in patient examination. Parameters were collected in CT facilities for common procedures such as head, chest, pelvic and cervical spine (c-spine) imaging. The dose descriptors considered were volume computed tomography dose index (CTDIv) and dose length product (DLP). The DRLs were proposed at 75th percentile CTDIv for head (without and with contrast materials), chest (without and with contrast materials), pelvic and c-spine only without contrast materials; their values were 52, 52, 17, 14, 14 and 38mGy, respectively. Whereas, DLP values for the aforementioned protocols were 1237, 1459, 625, 565, 605 and 1106mGy.cm, respectively. This study fruitfully developed the DRLs for head, chest, pelvic and c-spine and can be accepted for clinical purposes.

Dose optimization of adult head computed tomography examination in an academic hospital in Ghana

The study investigated radiation doses and image quality of adult head CT and optimization options using an anthropomorphic RANDO phantom on the only available AquilionONE CT scanner in Ghana. Dose length product (DLP) and volume-weighted CT dose index (CTDIvol) dose descriptors were retrospectively obtained from 402 adult head CT examinations performed (from 2020 to 2021) at a Ghanaian hospital, while the effective dose (Deff) was estimated from the product of the DLP and a convention coefficient (k = 0.0023). Using the same routine head CT protocol, the anthropomorphic RANDO phantom was scanned with the hospital's 640-slice Toshiba AquilionONE CT scanner. Subsequently, exposure factors were varied to study their effects on the dose and image quality. The adult head and phantom images were obtained in Digital Imaging and Communications in Medicine (DICOM) format, and their signal-to-noise (SNR) ratios were analyzed with ImageJ software. The facility's mean CTDIvol, DLP, and effective dose (Deff) were 86.00 ± 0.00 mGy, 1559.68 ± 197.18 mGy cm, and 3.57 ± 0.46 mSv respectively (SNR = 7.04). For a fixed tube potential, CTDIvol, DLP, and Deff of 51.30 mGy, 1013.80 mGy cm, and 2.33 mSv were respectively achieved (SNR = 5.49) after optimization. Using automatic exposure control (AEC) in the optimization process, the respective CTDIvol, DLP and Deff values were 59.50 mGy, 1176.00 mGy cm and 2.70 mSv (SNR = 5.62). We conclude that substantial Deff reductions of 40.4% and 31.0% using a fixed tube potential, and AEC while maintaining diagnostic image quality were respectively achieved. The protocols associated with these dose-reductions are, therefore, recommended as optimization measures for head CT on the AquilionONE scanner in Ghana.

Is it necessary to define new diagnostic reference levels during pandemics like the Covid19-?

IntroductionThis study intended to assess the dose length product (DLP), effective cumulative radiation dose (E.D.), and additional cancer risk (ACR) due to a chest CT scan to detect or follow up the Covid-19 disease in four university-affiliated hospitals that used different imaging protocols. Indeed, this study aimed to examine the differences in decision-making between different imaging centers in choosing chest CT imaging protocols during the pandemic, and to assess whether a new diagnostic reference level (DRL) is needed in pandemic situations. MethodsThis retrospective study assessed the E.D. of all chest imagings for Covid-19 for six months in four different hospitals in our country. Imaging parameters and DLP (mGy.cm) were recorded. The E.D.s and ACRs from chest CT scans were calculated using an online calculator. ResultsThousand-six hundred patients were included in the study. The mean cumulative dose due to chest CT was 3.97 mSv which might cause 2.59 × 10−2 ACR. The mean cumulative E.D. in different hospitals was in the range of 1.96–9.51 mSv. ConclusionsThe variety of mean E.D.s shows that different hospitals used different imaging protocols. Since there is no defined DRL in the pandemic, some centers use routine protocols, and others try to reduce the dose but insufficiently.In pandemics such as Covid-19, when CT scan is used for screening or follow-up, DLPs can be significantly lower than in normal situations. Therefore, international regularized organizations such as the international atomic energy agency (IAEA) or the international commission on radiological protection (IRCP) should provide new DRL ranges.

A new approach to dose reference levels in pediatric CT: Age and size-specific dose estimation

BackgroundAlthough paediatrics' are more radio-sensitivity than adults, the number of requested paediatric CT examinations is increasing globally. Significant efforts have been focused on achieving the lowest possible radiation dose for paediatric patients, particularly adjusting for size differences. This study aims to establish Diagnostic Reference Levels (DRLs) for paediatric patients based on size-specific dose estimates (SSDE). MethodIn this retrospective national study, CT scans for brain, chest, abdominopelvic, and chest, abdomen, and pelvis (CAP) were collected from four hospitals in Jordan undergoing paediatric CT scans. A total of 1818 cases were randomly selected in four age categories (<1 year, 1–4 years, 5–10 years, 11–18 years). The SSDE values were determined by multiplying the volume CT dose index (CTDIvol) with the conversion factor extracted from the American Association of Physicists in Medicine Report 204. ResultsVariations exist between the DRLs between the different hospitals, age groups, and variations in protocols with different types of CT scanners. The DRL values (CTDIvol, dose-length product (DLP) and SSDE) for the four age categories were as follows; <1 year: brain (47.88 mGy, 741.67 mGy cm and 58.40 mGy), chest (5.65 mGy, 124 mGy cm and 13.91 mGy), abdominopelvic (12.65 mGy, 321.5 mGy cm and 28.72 mGy) and CAP (16.12 mGy, 507.72 mGy cm and 38.04 mGy). 1–4 years, brain (54.79 mGy, 979.12 mGy cm and 55.88 mGy), chest (7.37 mGy, 220.85 mGy cm and 14.68 mGy), abdominopelvic (16.16 mGy, 424.72 mGy cm and 32.68 mGy) and CAP (16.13 mGy, 742.1 mGy cm and 33.54 mGy). 5–10 years: brain (65.03 mGy, 1129.94 mGy cm and 55.92 mGy), chest (12.57 mGy, 383.9 mGy cm and 22.45 mGy), abdominopelvic (12.34 mGy, 450.75 mGy cm and 22.23 mGy) and CAP (13.46 mGy, 748.85 mGy cm and 25.69 mGy). 11–18 years, brain (60.7 mGy, 1207.9 mGy cm and 41.81 mGy), chest examination (12.94 mGy, 496.2 mGy cm and 20.49 mGy), abdominopelvic (16.13 mGy, 803.07 mGy cm and 23.06 mGy) and CAP (16.13 mGy, 1101.5 mGy cm and 23.85 mGy). ConclusionThere were increases in CTDIvol, DLP, and SSDE with ascending age groups. SSDE and age are closely matched to delivered radiation in paediatric CT; however, radiation dose levels remain high in Jordan. This work highlights the need for caution when administering radiation in the paediatric population.

Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster

IntroductionThe use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDIvol measured in mGy) and dose-length product (DLP measured in mGy.cm). MethodsData from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDIvol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values. ResultsA total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP. ConclusionThe establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Diagnostic Validity and Reliability of Low-Dose Prospective ECG-Triggering Cardiac CT in Preoperative Assessment of Complex Congenital Heart Diseases (CHDs).

For the precise preoperative evaluation of complex congenital heart diseases (CHDs) with reduced radiation dose exposure, we assessed the diagnostic validity and reliability of low-dose prospective ECG-gated cardiac CT (CCT). Forty-two individuals with complex CHDs who underwent preoperative CCT as part of a prospective study were included. Each CCT image was examined independently by two radiologists. The primary reference for assessing the diagnostic validity of the CCT was the post-operative data. Infants and neonates were the most common age group suffering from complex CHDs. The mean volume of the CT dose index was 1.44 ± 0.47 mGy, the mean value of the dose-length product was 14.13 ± 5.4 mGy*cm, and the mean value of the effective radiation dose was 0.58 ± 0.13 mSv. The sensitivity, specificity, PPV, NPV, and accuracy of the low-dose prospective ECG-gated CCT for identifying complex CHDs were 95.6%, 98%, 97%, 97%, and 97% for reader 1 and 92.6%, 97%, 95.5%, 95.1%, and 95.2% for reader 2, respectively. The overall inter-reader agreement for interpreting the cardiac CCTs was good (κ = 0.74). According to the results of our investigation, low-dose prospective ECG-gated CCT is a useful and trustworthy method for assessing coronary arteries and making a precise preoperative diagnosis of complex CHDs.

ESTIMASI NILAI DOSIS PADA PEMERIKSAAN CT SCAN KEPALA DEWASA BERDASARKAN NILAI CTDIvol DAN DLP

ABSTRACT&#x0D; &#x0D; Background: Estimating the exact dose in CT Scan patients can be done by referring to an optimization index called DRL (Diagnostic Reference Level). Currently, the DRL for CT-Scans is expressed in CTDIvol (Computed Tomography Dose Index Volume) and DLP (Dose Length Product). The purpose of this study was to analyze the distribution of radiation dose values ​​on a CT scan of the adult head based on the CTDIvol and DLP values ​​referring to the IDRL reference from BAPETEN.&#x0D; Methods: This research is descriptive quantitative research with an observational approach. The Samples in this study were all patients who underwent Non-Contrast Head CT-Scan examinations at the radiology installation of Prof.Dr.I.G.N.G. Ngoerah Hospital, Denpasar for the period January-June 2022. Analysis of Results The estimation of radiation dose values ​​on CT Scan examinations of the adult head was based on the recapitulation of the distribution of CTDIvol and DLP values ​​obtained then compared with the IDRL 2021 values.&#x0D; Results: CTDIvol values ​​on non-Contrast head CT examination for all patients have varied values ​​with the lowest value of 23.28 mGy, the highest value of 62.7 mGy, an average of 47.58 mGy, and the 3rd quartile value of CTDIvol is 49.84 mGy. With the 75th percentile CTDIvol value of 49.84 mGy while the DLP value on the Head CT Examination varied in each patient with the lowest DLP value of 700.12 mGy*cm and the highest DLP value of 1597.19 mGy*cm and an average value of 1597.19 mGy*cm. DLP is 1057.95 mGy*Cm and the 3rd quartile value of DLP is 1133 mGy*cm.&#x0D; Conclusion: The CTDIvol and DLP values ​​for Non-Contrast Adult Head CT Scan examination at Prof.Dr.I.G.N.G. Ngoerah Hospital Denpasar are still below the reference from BAPETEN in IDRL 2021.

Contrast-Enhanced Chest Computed Tomography (CT) Scan with Low Radiation and Total Iodine Dose for Lung Cancer Detection Using Adaptive Statistical Iterative Reconstruction

Background: Contrast-enhanced chest computed tomography (CT) is useful for the detection and follow-up of patients with lung cancer. However, reaching balance between diagnostic image quality, radiation dose, and iodixanol dose is a cause of concern. Objectives: To investigate the clinical value of adaptive statistical iterative reconstruction (ASIR) in reducing the iodixanol content and radiation dose during contrast-enhanced chest CT scan for patients diagnosed with lung masses/nodules based on the analysis of image quality. Patients and Methods: This prospective study was conducted on 80 patients diagnosed with nodules or masses, who required contrast-enhanced chest CT scans. The experimental group (n = 40) was subjected to iohexol at a high concentration (350 mgI/L) with a tube voltage of 120 kVp and a filter back projection (FBP) reconstruction algorithm. The comparison group (n = 40) was subject to iodixanol at a lower concentration (270 mgI/L) with a tube voltage of 100 kVp and ASIR (blending ratio, 40%). The radiation dose and total iodixanol content, as well as subjective and objective evaluations of image quality, were analyzed and compared. Results: The two groups obtained non-significantly different subjective scores for five structures detected in the lung window and five structures detected in the mediastinal window, as well as the overall image (P &gt; 0.05 for all). Both the two-group images obtained diagnosis-acceptable scores (≥ 3 points) on displays of 10 structures and overall image quality. The mean CT value of vessels (100 kVp vs. 120 kVp: 314.90 ± 23.42 vs. 308.93 ± 21.40; P &gt; 0.05), standard deviation (13.03 ± 0.88 vs. 12.83 ± 0.90; P &gt; 0.05), and contrast-to-noise ratio (20.77 ± 2.20 vs. 20.36 ± 1.94; P &gt; 0.05) were not significantly different between two groups. However, the CT dose index, dose-length product, effective dose, and total iodine dose were reduced by 27.58%, 36.65%, 36.59%, and 22.86% in the 100-kVp group compared to the 120-kVp group. Conclusion: The ASIR showed great potential in reducing the radiation dose and iodine contrast dose, while maintaining good image quality and providing strong confidence for the diagnosis of lung cancer.

Estimation of effective and organ dose from chest CT

The aim of this study was to estimate radiation doses from high resolution chest computed tomography and pulmonary angiography examinations. This retrospective study was conducted between March 2021 and May 2022 for adult patients underwent CT examination in Royal Care Hospital - Sudan. A total of 180 patients were examined with 64-slice CT system (Aquilion 64, Toshiba Medical System Corporation). Data was collected using a validated survey, including scanner information, patient demographic data, scan protocol, and dose indices (CT dose index volume (CTDIvol) and dose length product (DLP)). Effective and organ doses were calculated by VirtualDose software based on ICRP 103.The result of the study revealed that CTDIvol for high resolution chest computed tomography and pulmonary angiography were 15.41 mGy and 14.61 mGy respectively. DLP were 476.5 mGy/cm and 520 mGy/cm, respectively. The calculated effective doses (ED) were 8.95 mSv and 8.57 mSv, respectively. The highest organ dose was recorded in the heart (20.09 mGy) and the lowest at the thyroid (3.41 mGy).The reported measurements provide a variety of data that CT departments can use for efforts aimed at quality improvement. Dose calculation software facilitates efficient documentation and comparison of local radiation dose data with national DRLs and helps to implement optimization if DRLs are exceeded the limits.

Comparing feasibility of different tube voltages and different concentrations of contrast medium in coronary CT angiography of overweight patients.

To compare image quality, radiation dose, and iodine intake of coronary computed tomography angiography (CCTA) acquired by wide-detector using different tube voltages and different concentrations of contrast medium (CM) for overweight patients. A total of 150 overweight patients (body mass index≥25 kg/m2) who underwent CCTA are enrolled and divided into three groups according to scan protocols namely, group A (120 kVp, 370 mgI/ml CM); group B (100 kVp, 350 mgI/ml CM); and group C (80 kVp, 320 mgI/ml CM). The CT values, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure-of-merit (FOM) of all images are calculated. Images are subjectively assessed using a 5-point scale. In addition, the CT dose index volume (CTDIvol) and dose length product (DLP) of each patient are recorded. The effective radiation dose (ED) is also calculated. Above data are then statistically analyzed. The mean CT values, SNR, CNR, and subjective image quality of group A are significantly lower than those of groups B and C (P < 0.001), but there is no significant difference between groups B and C (P > 0.05). FOMs show a significantly increase trend from group A to C (P < 0.001). The ED values and total iodine intake in groups B and C are 30.34% and 68.53% and 10.22% and 16.85% lower than those in group A, respectively (P < 0.001). The lower tube voltage and lower concentration of CM based on wide-detector allows for significant reduction in iodine load and radiation dose in CCTA for overweight patients comparing to routine scan protocols. It also enhances signal intensity of CCTA and maintains image quality.

Inter-observer agreement and image quality of model-based algorithm applied to the Coronary Artery Disease-Reporting and Data System score

PurposeTo evaluate the inter-observer agreement of the CAD-RADS reporting system and compare image quality between model-based iterative reconstruction algorithm (MBIR) and standard iterative reconstruction algorithm (IR) of low-dose cardiac computed tomography angiography (CCTA).MethodsOne-hundred-sixty patients undergone a 256-slice MDCT scanner using low-dose CCTA combined with prospective ECG-gated techniques were enrolled. CCTA protocols were reconstructed with both MBIR and IR. Each study was evaluated by two readers using the CAD-RADS lexicon. Vessels enhancement, image noise, signal-to-noise (SNR), and contrast-to-noise (CNR) were computed in the axial native images, and inter-observer agreement was assessed. Radiation dose exposure as dose–length product (DLP) and effective dose were finally reported.ResultsThe reliability analysis between the two readers was almost perfect for all CAD-RADS standard categories. Moreover, a significantly higher value of subjective qualitative analysis, SNR, and CNR in MBIR images compared to IR were found, due to a lower noise level (all p < 0.05). The mean DLP measured was 63.9 mGy*cm, and the mean effective dose was 0.9 mSv.ConclusionInter-observer agreement of CAD-RADS was excellent confirming the importance, the feasibility, and the reproducibility of the CAD-RADS scoring system for CCTA. Moreover, lower noise and higher image quality with MBIR compared to IR were found.Implications for practiceMBIR, by reducing noise and improving image quality, can help a better assessment of CAD-RADS, in comparison with standard IR algorithm.

Evaluation of Radiation Dose in Computed Tomography Angiography before Transcatheter Aortic Valve Implantation

Objective: To investigate the effective radiation dose and image quality of computed tomography angiography (CTA) before transcatheter aortic valve implantation (TAVI). Material and Methods: This study involved 65 participants, diagnosed with aortic valve stenosis and examined with CTA before TAVI. The total mAs, kVp, volume CT dose index (CTDIvol), and dose–length product (DLP) in each scanning phase were recorded. The effective dose was calculated by multiplying the DLP by the conversion coefficient (k=0.015 mSv/[mGy.cm]). For quantitative image analysis, circular regions of interest were placed on six levels of the aorta in the axial images. The CT attenuation value, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured. For qualitative analysis, two radiologists rated the image quality of the aortic root and aortoiliac pathway. Results: The mean CTDIvol and DLP were 23.59±5.19 mGy and 881.01±193.41 mGy.cm., respectively. The mean effective dose was 13.22±2.90 mSv; the whole-aorta CTA phase received the highest dose, followed by the coronary CTA and coronary artery calcium scoring phases (9.62±2.60, 2.44±1.13, and 1.16±0.55 mSv, respectively). Image quality ranged from good to excellent in all segments of the aorta. Conclusion: The mean effective radiation dose of the pre-TAVI CT examination using 256-multidetector CT was 22.91± 5.03 mSv. The image quality in the aorta was good to excellent. The main factors that affected the radiation dose were: body mass index, total mAs, and kVp.

Radiation Dose Optimization Based on Saudi National Diagnostic Reference Levels and Effective Dose Calculation for Computed Tomography Imaging: A Unicentral Cohort Study

Few studies have reviewed the reduction of doses in Computed tomography (CT), while various diagnostic procedures use ionizing radiation to explore the optimal dose estimate using multiple exposure quantities, including milliampere-seconds, kilovoltage peak, and pitch factors while controlling the CT dose index volume (CTDIvol) and dose length product (DLP). Therefore, we considered optimizing CT protocols to reduce radiation and organ doses during head, chest, abdominal, and pelvic CT examinations. For establishing institutional diagnostic reference levels as a benchmark to correlate with national diagnostic reference levels (NDRLs) in KSA conforming to international guidelines for radiation exposure, 3000 adult-patients underwent imaging of organs. Dose parameters were obtained using Monte Carlo software and adjusted using the Siemens Teamplay™ software. CTDIvol, DLP, and effective dose were 40.67 ± 3.8, 757 ± 63.2, and 1.74 ± 0.19, for head; 14.9 ± 1.38, 547 ± 42.9, and 7.27 ± 0.95 for chest; and 16.84 ± 1.45, 658 ± 53.4, and 10.2 ± 0.66 for abdomen/pelvis, respectively. The NDRL post-optimization comparison showed adequate CT exposure. Head CT parameters required additional optimization to match the NDRL. Therefore, calculations were repeated to assess radiation doses. In conclusion, doses could be substantially minimized by selecting parameters per clinical indication of the study, patient size, and examined body region. Additional dose reduction to superficial organs requires a shielding material.

Assessment of patients radiation doses associated with computed tomography coronary angiography

Computed tomography coronary angiography (CTCA) has generated tremendous interest over the past 20 years by using multidetector computed tomography (MDCT) because of its high diagnostic accuracy and efficacy in assessing patients with coronary artery disease. This technique is related to high radiation doses, which has raised serious concerns in the literature. Effective dose (E, mSv) may be a single parameter meant to reflect the relative risk from radiation exposure. Therefore, it is necessary to calculate this quantity to point to relative radiation risk. The objectives of this study are to evaluate patients' exposure during diagnostic CCTA procedures and to estimate the risks. Seven hundred ninety patients were estimated during three successive years. The patient's exposure was estimated based on a CT device's delivered radiation dose (Siemens Somatom Sensation 64 (64-MDCT)). The participating physicians obtained the parameters relevant to the radiation dose from the scan protocol generated by the CT system after each CCTA study. The parameters included the volume CT dose index (CTDIvol, mGy) and dose length product (DLP, mGy × cm). The mean and range of CTDIvol (mGy) and DLP (mGy × cm) for three respective year was (2018):10.8 (1.14–77.7) and 2369.8 ± 1231.4 (290.4–6188.9), (2019): 13.82 (1.13–348.5), and 2180.5 (501.8–9534.5) and (2020) 10.9 (0.7–52.9) and 1877.3 (149.4–5011.1), respectively. Patients' effective doses were higher compared to previous studies. Therefore, the CT acquisition parameter optimization is vital to reduce the dose to its minimal value.

Helical CT versus intermittent CT fluoroscopic guidance for musculoskeletal needle biopsies: impact on radiation exposure, procedure time, diagnostic yield, and adverse events.

Image-guided percutaneous needle biopsies are essential in the workup of musculoskeletal (MSK) lesions. While helical CT (HCT) is well established, intermittent CT fluoroscopy (iCTF) is an increasingly used alternative. The purpose of this study is to establish whether differences in subject radiation exposure, procedure time, yield, or adverse events exist between HCT and iCTF guidance. This retrospective cohort study included consecutive MSK needle biopsies performed on a single-CT scanner over a 12-month period at a tertiary academic center. Subject demographics, radiation dose, and outcomes were abstracted from the medical record. Comparisons between the two cohorts were performed using Student's t-test for continuous data and using Fisher's exact test for categorical data and a two-tailed p value less than 0.05 was considered significant. Two hundred sixteen adults (115 (53.2%) females) with a mean age of 58.8 ± 18.4years, underwent 216 biopsies (109 (50.5%) HCT guided, 107 (49.5%) iCTF guided) between June 2017 and June 2018. Dose-length product (DLP) and volume CT dose index (CTDIvol) were significantly higher for the HCT cohort (HCT 698.9 ± 400.8 mGycm vs iCTF 312.8 ± 170.8 mGycm; p < 0.005 and HCT 19.1mGy ± 8.8 vs iCTF 6.9mGy ± 1.5, p < 0.001). No significant difference in diagnostic yield, procedure time, or adverse event rate was identified. For CT-guided MSK needle biopsies, iCTF decreases subject radiation dose compared to HCT without negatively affecting outcomes. iCTF should be strongly considered by radiologists performing MSK biopsies given the reduced patient radiation exposure.