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Zhou W, Huo D, Browne LP, Zhou X, Weinman J. Universal 120-kV Dual-Source Ultra-High Pitch Protocol on the Photon-Counting CT System for Pediatric Abdomen of All Sizes: A Phantom Investigation Comparing With Energy-Integrating CT. Invest Radiol 2024; 59:719-726. [PMID: 38595181 DOI: 10.1097/rli.0000000000001080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
OBJECTIVES The purpose of this study is to determine if a universal 120-kV ultra-high pitch and virtual monoenergetic images (VMIs) protocol on the photon-counting computed tomography (PCCT) system can provide sufficient image quality for pediatric abdominal imaging, regardless of size, compared with protocols using a size-dependent kV and dual-source flash mode on the energy-integrating CT (EICT) system. MATERIALS AND METHODS One solid water insert and 3 iodine (2, 5, 10 mg I/mL) inserts were attached or inserted into phantoms of variable sizes, simulating the abdomens of a newborn, 5-year-old, 10-year-old, and adult-sized pediatric patients. Each phantom setting was scanned on an EICT using clinical size-specific kV dual-source protocols with a pitch of 3.0. The scans were performed with fixed scanning parameters, and the CTDI vol values of full dose were 0.30, 0.71, 1.05, and 7.40 mGy for newborn to adult size, respectively. In addition, half dose scans were acquired on EICT. Each phantom was then scanned on a PCCT (Siemens Alpha) using a universal 120-kV protocol with the same full dose and half dose as determined above on the EICT scanner. All other parameters matched to EICT settings. Virtual monoenergetic images were generated from PCCT scans between 40 and 80 keV with a 5-keV interval. Image quality metrics were compared between PCCT VMIs and EICT, including image noise (measured as standard deviation of solid water), contrast-to-noise ratio (CNR) (measured at iodine inserts with solid water as background), and noise power spectrum (measured in uniform phantom regions). RESULTS Noise at a PCCT VMI of 70 keV (7.0 ± 0.6 HU for newborn, 14.7 ± 1.6 HU for adult) is comparable ( P > 0.05, t test) or significantly lower ( P < 0.05, t test) compared with EICT (7.8 ± 0.8 HU for newborn, 15.3 ± 1.5 HU for adult). Iodine CNR from PCCT VMI at 50 keV (50.8 ± 8.4 for newborn, 27.3 ± 2.8 for adult) is comparable ( P > 0.05, t test) or significantly higher ( P < 0.05, t test) to the corresponding EICT measurements (57.5 ± 6.7 for newborn, 13.8 ± 1.7 for adult). The noise power spectrum curve shape of PCCT VMI is similar to EICT, despite PCCT VMI exhibiting higher noise at low keV levels. CONCLUSIONS The universal PCCT 120 kV with ultra-high pitch and postprocessed VMIs demonstrated equivalent or improved performance in noise (70 keV) and iodine CNR (50 keV) for pediatric abdominal CT, compared with size-specific kV images on the EICT.
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Affiliation(s)
- Wei Zhou
- From the Department of Radiology, University of Colorado, Anschutz Medical Campus, Aurora, CO (W.Z., D.H., L.P.B., J.W.); Department of Radiology, Children's Hospital Colorado, Aurora, CO (L.P.B., J.W.); and Bioinformatics and Computational Biology, University of Minnesota, St Paul, MN (X.Z.)
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Açıkgöz G. Investigating the Effects of Tube Current and Tube Voltage on Patient Dose in Computed Tomography Examinations with Principial Component Analysis and Cluster Analysis: Phantom Study. HEALTH PHYSICS 2024; 127:513-519. [PMID: 38787573 DOI: 10.1097/hp.0000000000001830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
ABSTRACT The aim of this study was to investigate the effects of tube current and tube voltage choices on patient dose in adult and pediatric CT protocols by qualitative analysis using Principal Component Analysis (PCA), cluster analysis, and statistical analysis.Dose length product (DLP), Effective mAs (Eff. mAs), and volume-weighted CT dose index (CTDIvol) dose descriptors were obtained from 16 adult and pediatric head phantom CT examinations. Different tube voltage and tube current values were selected in both pediatric head and adult head CT imaging protocols, and PCA and cluster analysis were applied to the data obtained for qualitative analysis of the relationship between CTDIvol, Eff. mAs and Total DLP values. The two principial components (PC) with the highest values among those obtained as a result of the PCA method were used. PC1 was 70.97%, and PC2 was 28.03%. In the cluster analysis, it was observed that the values obtained from pediatric and adult phantom CT scans were classified into two different clusters. The correlation coefficient for adult patients was r = 0.998, and for pediatric patients, the correlation coefficient was r = 0.947. When the obtained clusters were examined, the degree of closeness or distance of the variables could be observed. In the study, as a result of the analysis of CTDIvol, Eff. mAs and Total DLP data based on manufacturer data at different kV and mA values with PCA and cluster analysis, it was shown that pediatric patients could be exposed to more radiation than the adult patients.
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Affiliation(s)
- Güneş Açıkgöz
- Hatay Mustafa Kemal University Vocational School of Health Services, Hatay/Turkey. Güneş Açıkgöz, Hatay MKÜ: Hatay Mustafa Kemal Universitesi, Serinyol HMKU campus, Hatay 31100 (ORCID: 0000-0001-9118-3153 )
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Zhang J, Hu M, Cheng Q, Wang S, Liu Y, Zhou Y, Li J, Wei W. Achieving sub-millisievert CT colonography for accurate colorectal tumor detection using smart examination protocols: a prospective self-controlled study. Abdom Radiol (NY) 2024:10.1007/s00261-024-04557-5. [PMID: 39276190 DOI: 10.1007/s00261-024-04557-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 08/28/2024] [Accepted: 08/29/2024] [Indexed: 09/16/2024]
Abstract
PURPOSE To assess the feasibility of combining Auto-kVp selection technique, higher preset ASIR-V and noise index (NI) to realize individualized sub-mSv CT colonography (CTC) for accurate colorectal tumor detection and localization. METHODS Ninety patients with suspected colorectal cancer (CRC) were prospectively enrolled to undergo standard dose CTC (SDCTC) in the prone and ultra-low dose CTC (ULDCTC) in the supine position. SDCTC used 120 kVp, preset ASIR-V of 30%, SmartmA for a NI of 13; ULDCTC used Auto-kVp selection technique with 80 or 100 kVp, preset ASIR-V of 60%, SmartmA for a NI of 13 for 80 kVp, and NI of 15 for 100 kVp. The effective dose (ED), image quality [signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of colorectal neoplasms] between the two protocols were compared and the accuracies of tumor locations were evaluated for CTC in comparison with the surgery results. RESULTS The mean ED of the ULDCTC-80 kVp subgroup was 0.70 mSv, 71.43% lower than the 2.45 mSv for the 120 kVp group, while that of the ULDCTC-100 kVp subgroup was 0.98 mSv, 73.00% lower than the 3.63 mSv for the 120 kVp group (P < 0.001). The tumor SNR and CNR of the ULDCTC were higher than those of SDCTC (P < 0.05), while there was no difference in the subjective image quality between them with good inter-observer agreement (Kappa: 0.805-0.923). Both SDCTC and ULDCTC groups had high detection rate of colorectal tumors, along with good consistency in determining tumor location compared with surgery reports (Kappa: 0.718-0.989). CONCLUSION The combination of Auto-kVp selection, higher preset ASIR-V and NI achieves individualized sub-mSv CTC with good performance in detecting and locating CRC with surgery and consistent results between SDCTC and ULDCTC.
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Affiliation(s)
- Jingyi Zhang
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Mengting Hu
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Qiye Cheng
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Shigeng Wang
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Yijun Liu
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Yujing Zhou
- First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Jianying Li
- CT Research, GE Healthcare, Dalian, Dalian, China
| | - Wei Wei
- First Affiliated Hospital of Dalian Medical University, Dalian, China.
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Jiang Y, Jiang J, Li J, Hui Q, Tang J, Wang G, Zhang Y, Ma C. Enhancing acute stroke assessment: evaluating the clinical utility of the "Real" one-stop-shop scan protocol combining brain computed tomography perfusion and head-and-neck computed tomography angiography using a 512-slice detector computed tomography scanner. Clin Radiol 2024:S0009-9260(24)00413-6. [PMID: 39198108 DOI: 10.1016/j.crad.2024.07.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 09/01/2024]
Abstract
AIM To assess the efficiency and diagnostic value of the "real" one-stop-shop protocol integrating the computed tomography angiography (CTA) sequence of the head and neck into the computed tomography perfusion (CTP) acquisition using a 512-slice detector CT scanner in patients who suffered from acute ischemic stroke. MATERIALS AND METHODS This prospective study included 100 patients suspected of acute ischemic stroke. The patients were randomly divided into two groups: the control group (n=50) who underwent the traditional protocol (brain CTP and head-and-neck CTA examination separately) and the experimental group (n=50) who underwent a one-stop-shop protocol (combined brain CT perfusion and head-and-neck CTA, the CTA triggering time determined by a low-dose test bolus injection). The examination time, contrast-agent dosage, radiation dose, postprocessing time, and image quality were compared between the two groups. RESULTS Compared to the control group, the experimental group had a significantly lower total iodine contrast-agent dosage (80 vs. 100 ml, P<0.001) and shorter scan time (3.23 [3.13, 3.35] vs. 2.32 [2.17, 2.45] min, P<0.001). Additionally, the radiation dose exposure was lower in the experimental group than in the control group (5129.00 [5173, 5232] vs. 4681.35 [4555.12, 4822.95] mGy-cm, P<0.001). No statistically significant differences were observed between the two groups in terms of postprocessing time, head-and-neck CTA, and CTP imaging quality. CONCLUSION The one-stop-shop protocol enables effective detection of lesions, providing clear visualization of the location and degree of stenosis in the head-and-neck vessels. It achieves this with lower costs in scan time, contrast-agent dosage, and radiation dose compared to the traditional protocol and is thus worth considering as the first examination for patients who suffer from acute ischemic stroke.
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Affiliation(s)
- Y Jiang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Jiang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Li
- Department of Thyroid and Breast Surgery, General Hospital of Western Theater Command of Chinese People's Liberation Army, Chengdu, Sichuan, China
| | - Q Hui
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Tang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - G Wang
- CT Business Unit, Neusoft Medical System Company, Shenyang, China
| | - Y Zhang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - C Ma
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China.
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Sayed IS, Mohd Yusof MI. Techniques and Strategies to Minimize Radiation Exposure in Pediatric Computed Tomography (CT) Abdominal Examinations: A Review. Cureus 2024; 16:e67494. [PMID: 39310635 PMCID: PMC11416189 DOI: 10.7759/cureus.67494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2024] [Indexed: 09/25/2024] Open
Abstract
As children are more vulnerable to radiation-induced cancers and have longer life expectancies, it is essential to implement strict radiation protection measures in pediatric imaging. This study aimed to review radiation dose-minimizing measures in pediatric abdominal computed tomography (CT) examinations. A systematic search across various databases, including Web of Science, PubMed, SpringerLink, ScienceDirect, and Google Scholar, yielded a total of 7,314 articles. The search used keywords that aligned with the objectives of the study. This study included 77 publications after applying the criteria for inclusion and exclusion. We carefully reviewed these selected articles for compliance with the inclusion criteria and excluded them if they did not meet the specified criteria. Only 12 articles fulfilled the strict criteria. An in-depth review of 12 selected articles demonstrated the radiation dose reduction techniques and strategies, which include prefiltering and post-processing algorithms, careful adjustment of exposure parameters such as tube voltage (kVp) and current (mAs), and the establishment of diagnostic reference levels (DRL). Reduction of radiation exposure in pediatric CT imaging demands multifaceted approaches. To reduce the ionizing radiation dose while still obtaining high-quality diagnostic images, healthcare practitioners should adhere to DRL, adjust exposure factors, implement prefiltration, employ AI, and use post-processing algorithms.
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Affiliation(s)
- Inayatullah Shah Sayed
- Department of Diagnostic Imaging and Radiotherapy, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Kuantan, MYS
| | - Muhammad Irfan Mohd Yusof
- Department of Diagnostic Imaging and Radiotherapy, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Kuantan, MYS
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Chen LG, Kao HW, Wu PA, Sheu MH, Huang LC. Optimal image quality and radiation doses with optimal tube voltages/currents for pediatric anthropomorphic phantom brains. PLoS One 2024; 19:e0306857. [PMID: 39037987 PMCID: PMC11262643 DOI: 10.1371/journal.pone.0306857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/25/2024] [Indexed: 07/24/2024] Open
Abstract
OBJECTIVE Using pediatric anthropomorphic phantoms (APs), we aimed to determine the scanning tube voltage/current combinations that could achieve optimal image quality and avoid excessive radiation exposure in pediatric patients. MATERIALS AND METHODS A 64-slice scanner was used to scan a standard test phantom to determine the volume CT dose indices (CTDIvol), and three pediatric anthropomorphic phantoms (APs) with highly accurate anatomy and tissue-equivalent materials were studied. These specialized APs represented the average 1-year-old, 5-year-old, and 10-year-old children, respectively. The physical phantoms were constructed with brain tissue-equivalent materials having a density of ρ = 1.07 g/cm3, comprising 22 numbered 2.54-cm-thick sections for the 1-year-old, 26 sections for the 5-year-old, and 32 sections for the 10-year-old. They were scanned to acquire brain CT images and determine the standard deviations (SDs), effective doses (EDs), and contrast-to noise ratios (CNRs). The APs were scanned by 21 combinations of tube voltages/currents (80, 100, or 120 kVp/10, 40, 80, 120, 150, 200, or 250 mA) and rotation time/pitch settings of 1 s/0.984:1. RESULTS The optimal tube voltage/current combinations yielding optimal image quality were 80 kVp/80 mA for the 1-year-old AP; 80 kVp/120 mA for the 5-year-old AP; and 80 kVp/150 mA for the 10-year-old AP. Because these scanning tube voltages/currents yielded SDs, respectively, of 12.81, 13.09, and 12.26 HU, along with small EDs of 0.31, 0.34, and 0.31 mSv, these parameters and the induced values were expediently defined as optimal. CONCLUSIONS The optimal tube voltages/currents that yielded optimal brain image quality, SDs, CNRs, and EDs herein are novel and essentially important. Clinical translation of these optimal values may allow CT diagnosis with low radiation doses to children's heads.
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Affiliation(s)
- Li-Guo Chen
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Hung-Wen Kao
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Department of Radiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Ping-An Wu
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Ming-Huei Sheu
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Li-Chuan Huang
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Department of Medical Imaging and Radiological Sciences, Tzu Chi University of Science and Technology, Hualien, Taiwan
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Berris T, Myronakis M, Stratakis J, Perisinakis K, Karantanas A, Damilakis J. Is deep learning-enabled real-time personalized CT dosimetry feasible using only patient images as input? Phys Med 2024; 122:103381. [PMID: 38810391 DOI: 10.1016/j.ejmp.2024.103381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/28/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024] Open
Abstract
PURPOSE To propose a novel deep-learning based dosimetry method that allows quick and accurate estimation of organ doses for individual patients, using only their computed tomography (CT) images as input. METHODS Despite recent advances in medical dosimetry, personalized CT dosimetry remains a labour-intensive process. Current state-of-the-art methods utilize time-consuming Monte Carlo (MC) based simulations for individual organ dose estimation in CT. The proposed method uses conditional generative adversarial networks (cGANs) to substitute MC simulations with fast dose image generation, based on image-to-image translation. The pix2pix architecture in conjunction with a regression model was utilized for the generation of the synthetic dose images. The lungs, heart, breast, bone and skin were manually segmented to estimate and compare organ doses calculated using both the original and synthetic dose images, respectively. RESULTS The average organ dose estimation error for the proposed method was 8.3% and did not exceed 20% for any of the organs considered. The performance of the method in the clinical environment was also assessed. Using segmentation tools developed in-house, an automatic organ dose calculation pipeline was set up. Calculation of organ doses for heart and lung for each CT slice took about 2 s. CONCLUSIONS This work shows that deep learning-enabled personalized CT dosimetry is feasible in real-time, using only patient CT images as input.
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Affiliation(s)
- Theocharis Berris
- Department of Medical Physics, School of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - Marios Myronakis
- Department of Medical Physics, School of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - John Stratakis
- Department of Medical Physics, University Hospital of Iraklion, 71110 Iraklion, Crete, Greece
| | - Kostas Perisinakis
- Department of Medical Physics, School of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - Apostolos Karantanas
- Department of Radiology, School of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - John Damilakis
- Department of Medical Physics, School of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece.
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Fukamatsu F, Yamada A, Yamada K, Nonaka T, Aonuma T, Tsukahara Y, Kawakami S, Sasaki H, Fujinaga Y. Serial assessment of computed tomography angiography for pulmonary and systemic arteries using a reduced contrast agent dose for the diagnosis of systemic artery-to-pulmonary artery shunts. Jpn J Radiol 2024; 42:460-467. [PMID: 38148339 PMCID: PMC11056326 DOI: 10.1007/s11604-023-01520-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 11/23/2023] [Indexed: 12/28/2023]
Abstract
PURPOSE To evaluate the diagnostic performance and feasibility of a modified computed tomography (CT) scan protocol, we performed a serial assessment of the computed tomography angiography for pulmonary artery (CTA-P) and systemic artery (CTA-S) (CTA-PS) using a reduced contrast agent dose to diagnose systemic artery-to-pulmonary artery shunts (SPSs). MATERIALS AND METHODS Twenty-five patients who underwent multiphase contrast-enhanced chest CT and conventional chest angiography were included. Three image sets (CTA-P, CTA-S, and CTA-PS) were evaluated by two board-certified radiologists. The visualization of the CT image findings associated with SPSs, such as filling defects and enhancement in the pulmonary arteries, was evaluated using a 5-point scale. RESULTS The diagnostic performance (sensitivity, specificity, and accuracy) of CT imaging findings associated with SPSs in CTA-P and CTA-PS were as follows: CTA-P, 57.1%, 87.5%, and 62.0%; CTA-PS, 81.0%, 100.0%, and 84.0%. CT findings associated with SPSs in CTA-P were significantly sensitive to the CTA-PS protocol. There were no significant differences between the CTA-S and CTA-PS protocols. The area under the curve (AUC) of the CT imaging findings associated with SPSs in the CTA-P and CTA-PS groups was 0.835 and 0.911, respectively (P = 0.191). The AUC of the CT imaging findings associated with SPSs in CTA-S and CTA-PS were 0.891 and 0.926, respectively (P = 0.373). CONCLUSION CTA-PS using a reduced contrast agent dose protocol could improve the overall diagnostic confidence of SPSs, owing to better visualization of CT imaging findings associated with SPSs compared to individual assessments of CTA-P or CTA-S. Therefore, CTA-PS can be used as an alternative preembolization evaluation modality to conventional angiography in patients with hemoptysis suspected of having SPSs.
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Affiliation(s)
- Fumiaki Fukamatsu
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Akira Yamada
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
| | - Keiichi Yamada
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Tomofumi Nonaka
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Takanori Aonuma
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Yoshinori Tsukahara
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Satoshi Kawakami
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Hiroyuki Sasaki
- Division of Radiology, Shinshu University Hospital, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
| | - Yasunari Fujinaga
- Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
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Horst KK, Cao JY, McCollough CH, El-Ali A, Frush DP, Siegel MJ, Ramirez-Giraldo JC, O'Donnell T, Bach S, Yu L. Multi-institutional Protocol Guidance for Pediatric Photon-counting CT. Radiology 2024; 311:e231741. [PMID: 38771176 DOI: 10.1148/radiol.231741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Performing CT in children comes with unique challenges such as greater degrees of patient motion, smaller and densely packed anatomy, and potential risks of radiation exposure. The technical advancements of photon-counting detector (PCD) CT enable decreased radiation dose and noise, as well as increased spatial and contrast resolution across all ages, compared with conventional energy-integrating detector CT. It is therefore valuable to review the relevant technical aspects and principles specific to protocol development on the new PCD CT platform to realize the potential benefits for this population. The purpose of this article, based on multi-institutional clinical and research experience from pediatric radiologists and medical physicists, is to provide protocol guidance for use of PCD CT in the imaging of pediatric patients.
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Affiliation(s)
- Kelly K Horst
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Joseph Y Cao
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Cynthia H McCollough
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Alex El-Ali
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Donald P Frush
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Marilyn J Siegel
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Juan Carlos Ramirez-Giraldo
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Tom O'Donnell
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Steve Bach
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
| | - Lifeng Yu
- From the Department of Radiology, Division of Pediatric Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (K.K.H., C.H.M., L.Y.); Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (J.Y.C., D.P.F., S.B.); Department of Radiology, Division of Pediatric Radiology, NYU Grossman School of Medicine, New York, NY (A.E.A.); Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (M.J.S.); and Siemens Medical Solutions USA, Malvern, Pa (J.C.R.G., T.O.)
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10
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Tonkopi E, Tetteh MA, Gunn C, Ashraf H, Rusten SL, Safi P, Tinsoe NS, Colford K, Ouellet O, Naimi S, Johansen S. A multi-institutional assessment of low-dose protocols in chest computed tomography: Dose and image quality. Acta Radiol Open 2024; 13:20584601241228220. [PMID: 38304118 PMCID: PMC10829498 DOI: 10.1177/20584601241228220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 01/09/2024] [Indexed: 02/03/2024] Open
Abstract
Background Low-dose CT (LDCT) chest protocols have widespread clinical applications for many indications; as a result, there is a need for protocol assessment prior to standardization. Dalhousie University and Oslo Metropolitan University have a formally established cooperative relationship. Purpose The purpose is to assess radiation dose and image quality for LDCT chest protocols in seven different hospital locations in Norway and Canada. Material and methods Retrospective dosimetry data, volumetric CT dose index (CTDIvol), and dose length product (DLP) from 240 average-sized patients as well as CT protocol parameters were included in the survey. Effective dose (ED) and size-specific dose estimate (SSDE) were calculated for each examination. For a quantitative image quality analysis, noise, CT number, and signal-to-noise ratio (SNR) were determined for three regions in the chest. The contrast-to-noise ratio (CNR) was calculated for lung parenchyma in comparison to the subcutaneous fat. Differences in dose and image quality were evaluated by a single-factor ANOVA test. A two-sample t-test was performed to determine differences in means between individual scanners. Results The ANOVA test revealed significant differences (p < .05) in dose values for all scanners, including identical scanner models. Statistically significant differences (p < .05) were determined in mean values of the SNR distributions between the scanners in all three measured regions in the chest, as well as the CNR values. Conclusion The observed variations in dose and image quality measurements, even within the same hospitals and between identical scanner models, indicate a potential for protocol optimization in the involved hospitals in both countries.
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Affiliation(s)
- Elena Tonkopi
- Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada
- Department of Radiation Oncology, Dalhousie University, Halifax, NS, Canada
- Department of Diagnostic Imaging, Nova Scotia Health Authority, Halifax, NS, Canada
| | - Mercy Afadzi Tetteh
- Department of Diagnostic Imaging, Akershus University Hospital, Loerenskog, Norway
| | - Catherine Gunn
- Department of Radiation Oncology, Dalhousie University, Halifax, NS, Canada
- School of Health Sciences, Dalhousie University, Halifax, NS, Canada
| | - Haseem Ashraf
- Department of Diagnostic Imaging, Akershus University Hospital, Loerenskog, Norway
- Medicine Faculty, University of Oslo, Oslo Norway
| | - Sigrid Lia Rusten
- Health Faculty, Department of Life Sciences and Health, Oslo Metropolitan University Oslo, Norway
| | - Perkhah Safi
- Health Faculty, Department of Life Sciences and Health, Oslo Metropolitan University Oslo, Norway
| | - Nora Suu Tinsoe
- Health Faculty, Department of Life Sciences and Health, Oslo Metropolitan University Oslo, Norway
| | - Kylie Colford
- School of Health Sciences, Dalhousie University, Halifax, NS, Canada
| | - Olivia Ouellet
- School of Health Sciences, Dalhousie University, Halifax, NS, Canada
| | - Salma Naimi
- Department of Diagnostic Imaging, Akershus University Hospital, Loerenskog, Norway
| | - Safora Johansen
- Health Faculty, Department of Life Sciences and Health, Oslo Metropolitan University Oslo, Norway
- Department of Cancer Treatment, Oslo University Hospital, Oslo, Norway
- Health and Social Science Cluster, Singapore Institute of Technology, Singapore
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11
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Camoni L, Santos A, Luporsi M, Grilo A, Pietrzak A, Gear J, Zucchetta P, Bar-Sever Z. EANM procedural recommendations for managing the paediatric patient in diagnostic nuclear medicine. Eur J Nucl Med Mol Imaging 2023; 50:3862-3879. [PMID: 37555902 PMCID: PMC10611649 DOI: 10.1007/s00259-023-06357-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/23/2023] [Indexed: 08/10/2023]
Abstract
PURPOSE The manuscript aims to characterize the principles of best practice in performing nuclear medicine procedures in paediatric patients. The paper describes all necessary technical skills that should be developed by the healthcare professionals to ensure the best possible care in paediatric patients, as it is particularly challenging due to psychological and physical conditions of children. METHODS We performed a comprehensive literature review to establish the most relevant elements of nuclear medicine studies in paediatric patients. We focused the attention to the technical aspects of the study, such as patient preparation, imaging protocols, and immobilization techniques, that adhere to best practice principles. Furthermore, we considered the psychological elements of working with children, including comforting and distraction strategies. RESULTS The extensive literature review combined with practical conclusions and recommendations presented and explained by the authors summarizes the most important principles of the care for paediatric patient in the nuclear medicine field. CONCLUSION Nuclear medicine applied to the paediatric patient is a very special and challenging area, requiring proper education and experience in order to be performed at the highest level and with the maximum safety for the child.
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Affiliation(s)
- Luca Camoni
- University of Brescia, 25123, Brescia, Italy.
- Nuclear Medicine Department, University of Brescia, ASST Spedali Civili Di Brescia, P.Le Spedali Civili 1, 25123, Brescia, Italy.
| | - Andrea Santos
- Nuclear Medicine Department, CUF Descobertas Hospital, Lisbon, Portugal
| | - Marie Luporsi
- Department of Nuclear Medicine, Institut Curie, PSL Research University, 75005, Paris, France
- LITO Laboratory INSERM U1288, Institut Curie, 91440, Orsay, France
| | - Ana Grilo
- H&TRC - Health and Technology Research Center, ESTeSL - Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, Lisbon, Portugal
- CICPSI, Faculdade de Psicologia, Universidade de Lisboa, Alameda da Universidade, Lisbon, Portugal
| | - Agata Pietrzak
- Electroradiology Department, Poznan University of Medical Sciences, Poznan, Poland
- Nuclear Medicine Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Jonathan Gear
- Joint Department of Physics, Royal Marsden Hospital and Institute of Cancer Research, Sutton, UK
| | - Pietro Zucchetta
- Nuclear Medicine Department, Padova University Hospital, 35128, Padua, Italy
| | - Zvi Bar-Sever
- Department of Nuclear Medicine, Schneider Children's Medical Center, Tel-Aviv University, Petach Tikva, Israel
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12
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Karami V, Albosof M, Gholami M, Adeli M, Hekmatnia A, Sheidaei MFB, Behbahani AT, Sharif HS, Jafrasteh S. Tradeoffs between Radiation Exposure to the Lens of the Eyes and Diagnostic Image Quality in Pediatric Brain Computed Tomography. JOURNAL OF MEDICAL SIGNALS & SENSORS 2023; 13:208-216. [PMID: 37622039 PMCID: PMC10445673 DOI: 10.4103/jmss.jmss_19_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 09/04/2022] [Accepted: 03/16/2023] [Indexed: 08/26/2023]
Abstract
Background Computed tomography (CT) of the brain is associated with radiation exposure to the lens of the eyes. Therefore, it is necessary to optimize scan settings to keep radiation exposure as low as reasonably achievable without compromising diagnostic image information. The aim of this study was to compare the effectiveness of the five practical techniques for lowering eye radiation exposure and their effects on diagnostic image quality in pediatric brain CT. Methods The following scan protocols were performed: reference scan, 0.06-mm Pbeq bismuth shield, 30% globally lowering tube current (GLTC), reducing tube voltage (RTV) from 120 to 90 kVp, gantry tilting, and combination of gantry tilting with bismuth shielding. Radiation measurements were performed using thermoluminescence dosimeters. Objective and subjective image quality was evaluated. Results All strategies significantly reduced eye dose, and increased the posterior fossa artifact index and the temporal lobe artifact index, relative to the reference scan. GLTC and RTV increased image noise, leading to a decrease signal-to-noise ratio and contrast-to-noise ratio. Except for bismuth shielding, subjective image quality was relatively the same as the reference scan. Conclusions Gantry tilting may be the most effective method for reducing eye radiation exposure in pediatric brain CT. When the scanner does not support gantry tilting, GLTC might be an alternative.
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Affiliation(s)
- Vahid Karami
- Clinical Research Development Unit, Ganjavian Hospital, Dezful University of Medical Sciences, Dezful, Iran
| | - Mohsen Albosof
- Department of Biomedical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran
| | - Mehrdad Gholami
- Department of Medical Physics, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Mohammad Adeli
- Department of Biomedical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran
| | - Ali Hekmatnia
- Department of Radiology, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | | | - Hoda Sadat Sharif
- Clinical Research Development Unit, Ganjavian Hospital, Dezful University of Medical Sciences, Dezful, Iran
| | - Somayeh Jafrasteh
- Clinical Research Development Unit, Ganjavian Hospital, Dezful University of Medical Sciences, Dezful, Iran
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13
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Kazemi Z, Hajimiri K, Saghatchi F, Molazadeh M, Rezaeejam H. Assessment of the knowledge level of radiographers and CT technologists regarding computed tomography parameters in Iran. RADIATION MEDICINE AND PROTECTION 2023. [DOI: 10.1016/j.radmp.2023.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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14
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Markart S, Fischer TS, Wildermuth S, Dietrich TJ, Alkadhi H, Leschka S, Guesewell S, Ditchfield MR, Oezden I, Lutters G, Waelti SL. Organ-based tube current modulation and bismuth eye shielding in pediatric head computed tomography. Pediatr Radiol 2022; 52:2584-2594. [PMID: 35836016 DOI: 10.1007/s00247-022-05410-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/23/2021] [Accepted: 05/30/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Exposure of the eye lens to ionizing radiation results in cataract. Several dose optimization techniques to protect the lens are available for computed tomography (CT). OBJECTIVE The radiation dose to the eye lens, volume CT dose index (CTDIvol) and image quality of various methods of dose optimization were evaluated for pediatric head CT: automated tube current modulation (ATCM), automated tube voltage selection (ATVS), organ-based tube current modulation (OBTCM) and bismuth shielding. MATERIALS AND METHODS An anthropomorphic phantom of a 5-year-old child was scanned with nine protocols: no dose optimization technique and then adding different dose optimization techniques alone and in combination. Dose to the eye, thyroid and breast were estimated using metal oxide semiconductor field effect transistor (MOSFET) dosimetry. CTDIvol, influence of timing of shield placement, image noise and attenuation values in 13 regions of interest of the head and subjective image quality were compared. RESULTS The eye shield significantly reduced the eye lens dose when used alone, to a similar degree as when using all software-based techniques together. When used in combination with software-based techniques, the shield reduced the eye lens dose by up to 45% compared to the no dose optimization technique. Noise was significantly increased by the shield, most pronounced in the anterior portion of the eye. CONCLUSION The combination of ATCM, ATVS, OBTCM and a bismuth shield, with the shield placed after acquiring the localizer image, should be considered to reduce the radiation dose to the eye lens in pediatric head CT.
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Affiliation(s)
- Stefan Markart
- Department of Radiology and Nuclear Medicine, Children's Hospital of Eastern Switzerland, Claudiusstrasse 6, 9006, St. Gallen, Switzerland
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Tim S Fischer
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Simon Wildermuth
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Tobias J Dietrich
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Hatem Alkadhi
- Department of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sebastian Leschka
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Sabine Guesewell
- Clinical Trials Unit, Biostatistics, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Michael R Ditchfield
- Department of Diagnostic Imaging, Monash Children's Hospital, Clayton, Australia
| | - Ismail Oezden
- Radiation Protection and Medical Physics, Cantonal Hospital Aarau, Aarau, Switzerland
| | - Gerd Lutters
- Radiation Protection and Medical Physics, Cantonal Hospital Aarau, Aarau, Switzerland
| | - Stephan L Waelti
- Department of Radiology and Nuclear Medicine, Children's Hospital of Eastern Switzerland, Claudiusstrasse 6, 9006, St. Gallen, Switzerland.
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland.
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Hee Kim K, Choo KS, Jin Nam K, Lee K, Hwang JY, Park C, Jung Yang W. Cardiac CTA image quality of adaptive statistical iterative reconstruction-V versus deep learning reconstruction "TrueFidelity" in children with congenital heart disease. Medicine (Baltimore) 2022; 101:e31169. [PMID: 36281124 PMCID: PMC9592454 DOI: 10.1097/md.0000000000031169] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Several recent studies have reported that deep learning reconstruction "TrueFidelity" (TF) improves computed tomography (CT) image quality. However, no study has compared adaptive statistical repeated reconstruction (ASIR-V) using TF in pediatric cardiac CT angiography (CTA) with a low peak kilovoltage. OBJECTIVE This study aimed to determine whether ASIR-V or TF CTA image quality is superior in children with congenital heart disease (CHD). MATERIALS AND METHODS Fifty children (median age, 2 months; interquartile range, 0-5 months; 28 men) with CHD who underwent CTA were enrolled between June and September 2020. Images were reconstructed using 2 ASIR-V blending factors (80% and 100% [AV-100]) and 3 TF settings (low, medium, and high [TF-H] strength levels). For the quantitative analyses, 3 objective image qualities (attenuation, noise, and signal-to-noise ratio [SNR]) were measured of the great vessels and heart chambers. The contrast-to-noise ratio (CNR) was also evaluated between the left ventricle and the dial wall. For the qualitative analyses, the degree of quantum mottle and blurring at the upper level to the first branch of the main pulmonary artery was assessed independently by 2 radiologists. RESULTS When the ASIR-V blending factor level and TF strength were higher, the noise was lower, and the SNR was higher. The image noise and SNR of TF-H were significantly lower and higher than those of AV-100 (P < .01), except for noise in the right atrium and left pulmonary artery and SNR of the right ventricle. Regarding CNR, TF-H was significantly better than AV-100 (P < .01). In addition, in the objective assessment of the degree of quantum mottle and blurring, TF-H had the best score among all examined image sets (P < .01). CONCLUSION TF-H is superior to AV-100 in terms of objective and subjective image quality. Consequently, TF-H was the best image set for cardiac CTA in children with CHD.
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Affiliation(s)
- Kun Hee Kim
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
| | - Ki Seok Choo
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
- *Correspondence: Ki Seok Choo, Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beomeo-RI, Mulgeum-eup, Yangsan-si, Gyeongsangnam-do, 626-770, Korea (e-mail: )
| | - Kyoung Jin Nam
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
| | - Kyeyoung Lee
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
| | - Jae-Yeon Hwang
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
| | - ChanKue Park
- Department of Radiology, Pusan National University School of Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan-si, Gyeongsangnam-do, Korea
| | - Woo Jung Yang
- Barunmom Rehabilitation Medicine, Busanjin-gu, Busan, Korea
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Aly A, Ebrahimian S, Kharita MH, Heidous M, Ashruf MZ, Kumar D, Kalra MK, Al Naemi HM. Effect of technologist and patient attributes on centering for body CT examinations: Influence of cultural and ethnic factors. PLoS One 2022; 17:e0273227. [PMID: 35984837 PMCID: PMC9390905 DOI: 10.1371/journal.pone.0273227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/21/2022] [Indexed: 11/19/2022] Open
Abstract
There are no published data on the effect of patient and technologist gender and ethnicity attributes on off-centering in CT. Therefore, we assessed the impact of patient and technologist variations on off-centering patients undergoing body CT. With institutional review board approval, our retrospective study included 1000 consecutive adult patients (age ranged 22–96 years; 756 males: 244 females) who underwent chest or abdomen CT examinations. We recorded patient (age, gender, nationality, body weight, height,), technologist gender, and scan-related (scanner vendor, body region imaged, scan length, CT dose index volume, dose length product) information. Lateral and anteroposterior (AP) diameters were recorded to calculate effective diameter and size-specific dose estimate (SSDE). Off-centering represented the distance between the anterior-posterior centers of the scan field of view and the patient at the level of carina (for chest CT) and iliac crest (for abdomen CT). About 76% of the patients (760/1000) were off-centered with greater off-centering for chest (22 mm) than for abdomen (15 mm). Although ethnicity or patient gender was not a significant determinant of off-centering, technologist-patient gender mismatch was associated with a significantly greater frequency of off-centering (p<0.001). Off-centering below the gantry isocenter was twice as common as off-centering above the gantry isocenter (p<0.001). The latter occurred more frequently in larger patients and was associated with higher radiation doses than those centered below the isocenter (p<0.001). Technologists’ years of experience and patient factors profoundly affect the presence and extent of off-centering for both chest and abdomen CTs. Larger patients are more often off-centered than smaller patients.
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Affiliation(s)
- Antar Aly
- Hamad Medical Corporation, Doha, Qatar
- * E-mail:
| | - Shadi Ebrahimian
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | | | | | | | | | - Mannudeep K. Kalra
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
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Hu X, Yu Y. Explore the Value of Dual Source Computer Tomography Automatic Tube Current Regulation in Reducing the Radiation Dose of CTA in Lower Extremity Vessels. Front Surg 2022; 9:896370. [PMID: 35592130 PMCID: PMC9112657 DOI: 10.3389/fsurg.2022.896370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/06/2022] [Indexed: 11/13/2022] Open
Abstract
Objective To investigate the value of dual source computer tomography automatic tube current regulation in reducing the radiation dose of CTA in lower limb vessels. Methods From February 2020 to December 2021, 64 patients with lower limb artery CTA were selected in our hospital because of the symptoms of foot ischemia. According to the random number table, patients were divided into control group (treated with fixed tube current technology) and observation group (treated with automatic tube current regulation technology), with 32 cases in each group. All patients underwent a dual source computer tomography scan. Control group: tube voltage 120 kV, tube current 250 mA; Observation group: tube voltage was 80 kV, and reference tube current was 80–380 mA. Other scanning conditions of patients in the two groups were the same. CTDIvol, DLP and calculated SNR and CNR were recorded to obtain the ED. Results The values of CTDIvol, DLP and ED in the observation group were lower than those in the control group (P < 0.05). There was no significant difference in CT value, SD value, SNR value and CNR value of the femoral artery segment, popliteal artery segment and posterior tibial artery segment between the two groups (P > 0.05). The image quality scores of patients in the control group were slightly higher than those in the observation group, but there was no statistical difference between the two groups (P > 0.05). Conclusion The application of dual source computer tomography automatic tube current adjustment technology in CTA examination of lower limb vessels can automatically adjust the compensation output and realize the output of different tube currents in different thicknesses, densities and angles. On the premise of not affecting the image quality, the radiation dose in the scanning process to the maximum extent, and reasonably protect the examined patients.
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Affiliation(s)
- Xin Hu
- Department of Guangdong Armed Police Corps Hospital, Medical Engineering, Guangzhou, Guangdong, China
| | - Yi Yu
- School of Foreign Languages of Guangdong University of Technology, Guangzhou, Guangdong, China
- Correspondence: Yi Yu
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Martens B, Bosschee JGA, Van Kuijk SMJ, Jeukens CRLPN, Brauer MTH, Wildberger JE, Mihl C. Finding the optimal tube current and iterative reconstruction strength in liver imaging; two needles in one haystack. PLoS One 2022; 17:e0266194. [PMID: 35390018 PMCID: PMC8989341 DOI: 10.1371/journal.pone.0266194] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 03/15/2022] [Indexed: 11/19/2022] Open
Abstract
Objectives
The aim of the study was to find the lowest possible tube current and the optimal iterative reconstruction (IR) strength in abdominal imaging.
Material and methods
Reconstruction software was used to insert noise, simulating the use of a lower tube current. A semi-anthropomorphic abdominal phantom (Quality Assurance in Radiology and Medicine, QSA-543, Moehrendorf, Germany) was used to validate the performance of the ReconCT software (S1 Appendix). Thirty abdominal CT scans performed with a standard protocol (120 kVref, 150 mAsref) scanned at 90 kV, with dedicated contrast media (CM) injection software were selected. There were no other in- or exclusion criteria. The software was used to insert noise as if the scans were performed with 90, 80, 70 and 60% of the full dose. Consequently, the different scans were reconstructed with filtered back projection (FBP) and IR strength 2, 3 and 4. Both objective (e.g. Hounsfield units [HU], signal to noise ratio [SNR] and contrast to noise ratio [CNR]) and subjective image quality were evaluated. In addition, lesion detection was graded by two radiologists in consensus in another 30 scans (identical scan protocol) with various liver lesions, reconstructed with IR 3, 4 and 5.
Results
A tube current of 60% still led to diagnostic objective image quality (e.g. SNR and CNR) when IR strength 3 or 4 were used. IR strength 4 was preferred for lesion detection. The subjective image quality was rated highest for the scans performed at 90% with IR 4.
Conclusion
A tube current reduction of 10–40% is possible in case IR 4 is used, leading to the highest image quality (10%) or still diagnostic image quality (40%), shown by a pairwise comparison in the same patients.
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Affiliation(s)
- Bibi Martens
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
- * E-mail:
| | | | - Sander M. J. Van Kuijk
- Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Cécile R. L. P. N. Jeukens
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Maikel T. H. Brauer
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Joachim E. Wildberger
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Casper Mihl
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
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Sookpeng S, Martin CJ. A PHANTOM EVALUATION OF THE USE OF CT AUTOMATIC TUBE CURRENT MODULATION WITH LOW TUBE POTENTIALS FOR IODINATED CONTRAST STUDIES. RADIATION PROTECTION DOSIMETRY 2022; 198:188-195. [PMID: 35224645 DOI: 10.1093/rpd/ncac023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/29/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
This paper aimed to investigate effects of different tube voltage and image quality settings on radiation dose and image quality for patients undergoing computed tomography iodinated contrast studies using automatic tube current modulation system and to recommend settings to achieve improved radiation dose and image quality values. A Pagoda phantom with an additional rod of iodine contrast was scanned using different tube voltages and noise index (NI) settings. Size-specific dose estimate (SSDE) and image quality (noise, contrast, contrast-to-noise ratio (CNR) and figure of merit (FOM)) were analysed. Values of SSDE were maintained with similar NI settings. Contrast and CNR were higher for lower tube voltage settings. Better FOM values can be achieved with higher NI settings with the lower kVs. To achieve better CNR and SSDE compared with the standard setting of 120 kV, a 80 kV with an NI setting of 15 was recommended.
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Affiliation(s)
- Supawitoo Sookpeng
- Department of Radiological Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok 65000, Thailand
| | - Colin J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Gartnavel Royal Hospital, Glasgow G12 0XH, UK
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Individualized Scan Protocols in Abdominal Computed Tomography: Radiation Versus Contrast Media Dose Optimization. Invest Radiol 2021; 57:353-358. [PMID: 34935651 DOI: 10.1097/rli.0000000000000844] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND In contrast-enhanced abdominal computed tomography (CT), radiation and contrast media (CM) injection protocols are closely linked to each other, and therefore a combination is the basis for achieving optimal image quality. However, most studies focus on optimizing one or the other parameter separately. PURPOSE Reducing radiation dose may be most important for a young patient or a population in need of repetitive scanning, whereas CM reduction might be key in a population with insufficient renal function. The recently introduced technical solution, in the form of an automated tube voltage selection (ATVS) slider, might be helpful in this respect. The aim of the current study was to systematically evaluate feasibility of optimizing either radiation or CM dose in abdominal imaging compared with a combined approach. METHODS Six Göttingen minipigs (mean weight, 38.9 ± 4.8 kg) were scanned on a third-generation dual-source CT. Automated tube voltage selection and automated tube current modulation techniques were used, with quality reference values of 120 kVref and 210 mAsref. Automated tube voltage selection was set at 90 kV semimode. Three different abdominal scan and CM protocols were compared intraindividually: (1) the standard "combined" protocol, with the ATVS slider position set at 7 and a body weight-adapted CM injection protocol of 350 mg I/kg body weight, iodine delivery rate (IDR) of 1.1 g I/s; (2) the CM dose-saving protocol, with the ATVS slider set at 3 and CM dose lowered to 294 mg I/kg, resulting in a lower IDR of 0.9 g I/s; (3) the radiation dose-saving protocol, with the ATVS slider position set at 11 and a CM dose of 441 mg I/kg and an IDR 1.3 g I/s, respectively. Scans were performed with each protocol in arterial, portal venous, and delayed phase. Objective image quality was evaluated by measuring the attenuation in Hounsfield units, signal-to-noise ratio, and contrast-to-noise ratio of the liver parenchyma. The overall image quality, contrast quality, noise, and lesion detection capability were rated on a 5-point Likert scale (1 = excellent, 5 = very poor). Protocols were compared for objective image quality parameters using 1-way analysis of variance and for subjective image quality parameters using Friedman test. RESULTS The mean radiation doses were 5.2 ± 1.7 mGy for the standard protocol, 7.1 ± 2.0 mGy for the CM dose-saving protocol, and 3.8 ± 0.4 mGy for the radiation dose-saving protocol. The mean total iodine load in these groups was 13.7 ± 1.7, 11.4 ± 1.4, and 17.2 ± 2.1 g, respectively. No significant differences in subjective overall image or contrast quality were found. Signal-to-noise ratio and contrast-to-noise ratio were not significantly different between protocols in any scan phase. Significantly more noise was seen when using the radiation dose-saving protocol (P < 0.01). In portal venous and delayed phases, the mean attenuation of the liver parenchyma significantly differed between protocols (P < 0.001). Lesion detection was significantly better in portal venous phase using the CM dose-saving protocol compared with the radiation dose-saving protocol (P = 0.037). CONCLUSIONS In this experimental setup, optimizing either radiation (-26%) or CM dose (-16%) is feasible in abdominal CT imaging. Individualizing either radiation or CM dose leads to comparable objective and subjective image quality. Personalized abdominal CT examination protocols can thus be tailored to individual risk assessment and might offer additional degrees of freedom.
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Euler A, Zadory M, Breiding PS, Sartoretti T, Ghafoor S, Froehlich JM, Donati OF. Realistic Kidney Tissue Surrogates for Multienergy Computed Tomography-Feasibility and Estimation of Energy-Dependent Attenuation Thresholds for Renal Lesion Enhancement in Low-kV and Virtual Monoenergetic Imaging. Invest Radiol 2021; 56:791-798. [PMID: 33899757 DOI: 10.1097/rli.0000000000000790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE The aims of this study were to assess if kidney tissue surrogates (KTSs) are superior to distilled water-iodine solutions in the emulation of energy-dependent computed tomography (CT) attenuation characteristics of renal parenchyma and to estimate attenuation thresholds for definite lesion enhancement for low-kV single-energy and low-keV dual-energy virtual monoenergetic imaging. METHODS A water-filled phantom (diameter, 30 cm) with multiple vials was imaged on a dual-source dual-energy CT (DS-DE) and a single-source split-filter dual-energy CT (SF-DE), both in single-energy mode at 80, 100, 120, 140 kVp and in dual-energy mode at 80/Sn150, 90/Sn150, and 100/Sn150 kVp for DS-DE and AuSn120 kVp for SF-DE. Single-energy images, linear-blended dual-energy images, and virtual monoenergetic imaging at energy levels from 40 to 190 keV were reconstructed. First, attenuation characteristics of KTS in solid and liquid consistencies were compared. Second, solid KTSs were developed to match the CT attenuation of unenhanced renal parenchyma at 120 kVp as retrospectively measured in 100 patients. Third, CT attenuation of KTS-iodine and water-iodine solutions at 8 different iodine concentrations (0-10 mg I/mL) were compared as a function of tube voltage and of keV level using multiple linear regression models. Energy-dependent attenuation thresholds for definite lesion enhancement were calculated. RESULTS Unenhanced renal parenchyma at 120 kVp measured on average 30 HU on both scanners in the patient cohort. Solid KTS with a water content of 80% emulated the attenuation of unenhanced renal parenchyma (30 HU) more accurately compared with water-iodine solutions (0 HU). Attenuation difference between KTS-iodine and water-iodine solutions converged with increasing iodine concentration and decreasing x-ray energy due to beam-hardening effects. A slight attenuation difference of approximately 2 HU was found between the 2 CT scanners. Attenuation thresholds for definite lesion enhancement were dependent on tube voltage and keV level and ranged from 16.6 to 33.2 HU and 3.2 to 68.3 HU for single-energy and dual-energy CT scan modes for DS-DE and from 16.1 to 34.3 HU and 3.3 to 92.2 HU for SF-DE. CONCLUSIONS Kidney tissue surrogates more accurately emulate the energy-dependent CT attenuation characteristics of renal parenchyma for multienergy CT compared with conventional water-iodine approaches. Energy-dependent thresholds for definite lesion enhancement could facilitate lesion characterization when imaging at different energies than the traditional 120 kVp.
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Affiliation(s)
- André Euler
- From the Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, University of Zurich
| | | | - Philipe Sebastian Breiding
- From the Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, University of Zurich
| | | | - Soleen Ghafoor
- From the Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, University of Zurich
| | | | - Olivio Fabrizio Donati
- From the Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, University of Zurich
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22
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Sookpeng S, Martin CJ, López-González MR. Simplified approach to estimation of organ absorbed doses for patients undergoing abdomen and pelvis CT examination. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:1288-1303. [PMID: 34488213 DOI: 10.1088/1361-6498/ac241d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
The volumetric computed tomography (CT) dose index (CTDIvol) is the measure of output displayed on CT consoles relating to dose within a standard phantom. This gives a false impression of doses levels within the tissues of smaller patients in Southeast Asia. A size-specific dose estimate (SSDE) can be calculated from the CTDIvolto provide an assessment of doses at specific positions within a scan using size-specific conversion factors. SSDE is derived using the water equivalent diameter (Dw) of the patient, but calculation ofDwrequires sophisticated computer software. This study aimed to evaluate relationships betweenDWand effective diameter (DEff), which can be measured more readily, in order to estimate SSDE at various positions within a routine clinical abdomen and pelvis CT examination for Thai patients. An in-house ImageJ algorithm was developed to measureDw, effective diameter (DEff), and SSDE on CT slices located at the heart, liver, kidneys, colon, and bladder, on 181 CT examinations of abdomen and pelvis. Relationships betweenDEffandDwwere determined, and values of organ absorbed dose usingDEffwere estimated. This approach was validated using a second cohort of 54 patients scanned on a different CT scanner. The results revealed that ratios betweenDEffandDwat the heart level were 1.11-1.13 and those for the others were about 1.00. Additionally, the SSDE/CTDIvolratio was estimated for each organ in terms of exponential functions using the relationships betweenDwandDEfffor individual organs. In summary, this study proposed a simple method for estimation of organ absorbed doses for Southeast Asian patients undergoing abdomen and pelvis CT examinations where sophisticated computer software is not available.
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Affiliation(s)
- S Sookpeng
- Radiological Technology Department, Faculty of Allied Health Sciences, Naresuan University, Muang, Phitsanulok Province, 65000 Thailand
| | - C J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - M R López-González
- Department of Clinical Physics and Bioengineering, Institute of Neurosciences and Psychology, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
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Kayun Z, Karim M, Muhammad N, Aljewaw O, Chew M, Harun H. Implication of applying iterative reconstruction on Low Contrast Detectability in CT brain examination. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hawarihewa PM, Satharasinghe D, Amalaraj T, Jeyasugiththan J. An assessment of Sri Lankan radiographer's knowledge and awareness of radiation protection and imaging parameters related to patient dose and image quality in computed tomography (CT). Radiography (Lond) 2021; 28:378-386. [PMID: 34728139 DOI: 10.1016/j.radi.2021.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 10/07/2021] [Accepted: 10/11/2021] [Indexed: 12/11/2022]
Abstract
INTRODUCTION As computed tomography (CT) examinations have considerably risen, safe operation is essential to reduce the patients' dose. The main objective of this study was to evaluate the level of knowledge and awareness regarding the CT exposure parameters and radiation protection in CT imaging among Sri Lankan radiographers. METHODS An online survey-based study was devised and distributed among the Sri Lankan CT radiographers working in 63 CT units. Questions were divided into three subsections that collected data on the participants' demographic features, knowledge of the radiation protection, and imaging parameters. RESULTS Eighty-eight radiographers from 32 CT units (out of 63 CT units) distributed across 11 districts (out of 27 districts) participated in this survey.The percentages of correct responses for the questions related to radiation protection, imaging parameters, noise, Diagnostic Reference Level (DRL), and CT dosimetric parameters were 71%, 79%, 87%, 50%, and 66%, respectively. Although the years of experience did not influence any of above aspects, the level of education significantly impacted the knowledge about radiation protection, exposure parameters, and noise. CONCLUSION The radiographer's knowledge of radiation protection and most imaging parameters associated with patient safety and image quality is satisfactory. However, findings also show that participants should fill the knowledge gap in radiation-related risks, CT exposure parameters, dosimetric parameters, and DRL. IMPLICATIONS FOR PRACTICE The study suggests the necessity of initiating continuous education programs for radiographers in line with national radiation protection legislation requirements that can be linked with code of practice.
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Affiliation(s)
- P M Hawarihewa
- Department of Nuclear Science, University of Colombo, Colombo, Sri Lanka
| | - D Satharasinghe
- Department of Nuclear Science, University of Colombo, Colombo, Sri Lanka
| | - T Amalaraj
- Department of Nuclear Science, University of Colombo, Colombo, Sri Lanka
| | - J Jeyasugiththan
- Department of Nuclear Science, University of Colombo, Colombo, Sri Lanka.
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Thierry-Chef I, Ferro G, Le Cornet L, Dabin J, Istad TS, Jahnen A, Lee C, Maccia C, Malchair F, Olerud HM, Harbron RW, Figuerola J, Hermen J, Moissonnier M, Bernier MO, Bosch de Basea MB, Byrnes G, Cardis E, Hauptmann M, Journy N, Kesminiene A, Meulepas JM, Pokora R, Simon SL. Dose Estimation for the European Epidemiological Study on Pediatric Computed Tomography (EPI-CT). Radiat Res 2021; 196:74-99. [PMID: 33914893 DOI: 10.1667/rade-20-00231.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/26/2021] [Indexed: 11/03/2022]
Abstract
Within the European Epidemiological Study to Quantify Risks for Paediatric Computerized Tomography (EPI-CT study), a cohort was assembled comprising nearly one million children, adolescents and young adults who received over 1.4 million computed tomography (CT) examinations before 22 years of age in nine European countries from the late 1970s to 2014. Here we describe the methods used for, and the results of, organ dose estimations from CT scanning for the EPI-CT cohort members. Data on CT machine settings were obtained from national surveys, questionnaire data, and the Digital Imaging and Communications in Medicine (DICOM) headers of 437,249 individual CT scans. Exposure characteristics were reconstructed for patients within specific age groups who received scans of the same body region, based on categories of machines with common technology used over the time period in each of the 276 participating hospitals. A carefully designed method for assessing uncertainty combined with the National Cancer Institute Dosimetry System for CT (NCICT, a CT organ dose calculator), was employed to estimate absorbed dose to individual organs for each CT scan received. The two-dimensional Monte Carlo sampling method, which maintains a separation of shared and unshared error, allowed us to characterize uncertainty both on individual doses as well as for the entire cohort dose distribution. Provided here are summaries of estimated doses from CT imaging per scan and per examination, as well as the overall distribution of estimated doses in the cohort. Doses are provided for five selected tissues (active bone marrow, brain, eye lens, thyroid and female breasts), by body region (i.e., head, chest, abdomen/pelvis), patient age, and time period (1977-1990, 1991-2000, 2001-2014). Relatively high doses were received by the brain from head CTs in the early 1990s, with individual mean doses (mean of 200 simulated values) of up to 66 mGy per scan. Optimization strategies implemented since the late 1990s have resulted in an overall decrease in doses over time, especially at young ages. In chest CTs, active bone marrow doses dropped from over 15 mGy prior to 1991 to approximately 5 mGy per scan after 2001. Our findings illustrate patterns of age-specific doses and their temporal changes, and provide suitable dose estimates for radiation-induced risk estimation in epidemiological studies.
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Affiliation(s)
- Isabelle Thierry-Chef
- International Agency for Research on Cancer, Lyon, France
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Ciber Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Gilles Ferro
- International Agency for Research on Cancer, Lyon, France
| | - Lucian Le Cornet
- Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center Mainz, Mainz, Germany
- German Cancer Research Center, Heidelberg, Germany
| | - Jérémie Dabin
- Belgian Nuclear Research Centre, SCK CEN, Mol, Belgium
| | - Tore S Istad
- Norwegian Radiation and Nuclear Safety Authority, NO-0213 Oslo, Norway
| | - Andreas Jahnen
- Luxembourg Institute of Science and Technology, Esch-sur-Alzette, Luxembourg
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland
| | | | | | - Hilde M Olerud
- University of South-Eastern Norway, Faculty of Health and Social Sciences, Kongsberg, Norway
| | - Richard W Harbron
- Institute of Health and Society, Newcastle University (UNEW), Newcastle upon Tyne, United Kingdom
- NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, United Kingdom
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Ciber Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Jordi Figuerola
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Ciber Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Johannes Hermen
- Luxembourg Institute of Science and Technology, Esch-sur-Alzette, Luxembourg
| | | | - Marie-Odile Bernier
- Institut de Radioprotection et de Sûreté Nucléaire, Laboratoire d'épidémiologie des Rayonnements Ionisants, Fontenay-aux-Roses, France
| | - Magda Bosch Bosch de Basea
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Ciber Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Graham Byrnes
- International Agency for Research on Cancer, Lyon, France
| | - Elisabeth Cardis
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Ciber Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Michael Hauptmann
- Department of Epidemiology and Biostatistics, Netherlands Cancer Institute, Amsterdam, the Netherlands
- Institute of BiostatisTics and Registry Research, Medical University Brandenburg Theodor Fontane, Neuruppin, Germany
| | - Neige Journy
- Institut de Radioprotection et de Sûreté Nucléaire, Laboratoire d'épidémiologie des Rayonnements Ionisants, Fontenay-aux-Roses, France
- French National Institute of Health and Medical Research (Inserm) Unit 1018, Centre for Research in Epidemiology and Population Health (CESP), Cancer and Radiations Group, Gustave Roussy, Villejuif, France
| | | | - Johanna M Meulepas
- Department of Epidemiology and Biostatistics, Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Roman Pokora
- Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center Mainz, Mainz, Germany
| | - Steven L Simon
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland
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Zhang T, Geng X, Li D, Xu Y, Zhao Y. Comparison of the image quality and radiation dose of different scanning modes in head-neck CT angiography. Dentomaxillofac Radiol 2021; 50:20200428. [PMID: 33353399 DOI: 10.1259/dmfr.20200428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To analyze and compare the radiation dose and image quality of different CT scanning modes on head-neck CT angiography. METHODS A total of 180 patients were divided into Group A and Group B. The groups were further subdivided according to different scanning modes: subgroups A1, A2, A3, B1, B2, and B3. Subgroups A1 and B1 used conventional CT protocol, subgroups A2 and B2 used the kV-Assist scan mode, and subgroups A3 and B3 used the dual-energy gemstone spectral imaging protocol. The CT dose index and dose-length product were recorded. The objective image quality and subjective image evaluation was conducted by two independent radiologists. RESULTS The signal-to-noise ratios, contrast-to-noise ratios, and subjective scores of subgroups A3 and B3 were higher than the other subgroups. In subgroups B1 and B2, the subjective scores of 9 patients and 12 patients were lower than 3, respectively. The subjective scores of subgroups B1 and B2 were lower than the other subgroups. There was no statistically significant difference in signal-to-noise ratios, contrast-to-noise ratios, and subjective scores between subgroups A1 and A2. The effective dose of subgroup A2 was 41.7 and 36.4% lower than that in subgroups A1 and A3, respectively (p < 0.05). In Group B, there were no statistically significant differences in CT dose indexvol, dose-length product, and ED among the subgroups (p > 0.05). CONCLUSION In the head-neck CT angiography, the kV-Assist scan mode is recommended for patients with body mass index between 18.5 and 34.9 kg m-2; gemstone spectral imaging scanning mode is recommended for patients with body mass index ≥34.9 kg m-2.
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Affiliation(s)
- Tianle Zhang
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Xue Geng
- Department of Radiology, Baoding No.2 hospital, Baoding, China
| | - Dongxue Li
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Yize Xu
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Yongxia Zhao
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
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Racine D, Brat HG, Dufour B, Steity JM, Hussenot M, Rizk B, Fournier D, Zanca F. Image texture, low contrast liver lesion detectability and impact on dose: Deep learning algorithm compared to partial model-based iterative reconstruction. Eur J Radiol 2021; 141:109808. [PMID: 34120010 DOI: 10.1016/j.ejrad.2021.109808] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/12/2021] [Accepted: 05/30/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To compare deep learning (True Fidelity, TF) and partial model based Iterative Reconstruction (ASiR-V) algorithm for image texture, low contrast lesion detectability and potential dose reduction. METHODS Anthropomorphic phantoms (mimicking non-overweight and overweight patient), containing lesions of 6 mm in diameter with 20HU contrast, were scanned at five different dose levels (2,6,10,15,20 mGy) on a CT system, using clinical routine protocols for liver lesion detection. Images were reconstructed using ASiR-V 0% (surrogate for FBP), 60 % and TF at low, medium and high strength. Noise texture was characterized by computing a normalized Noise Power Spectrum filtered by an eye filter. The similarity against FBP texture was evaluated using peak frequency difference (PFD) and root mean square deviation (RMSD). Low contrast detectability was assessed using a channelized Hotelling observer and the area under the ROC curve (AUC) was used as figure of merit. Potential dose reduction was calculated to obtain the same AUC for TF and ASiR-V. RESULTS FBP-like noise texture was more preserved with TF (PFD from -0.043mm-1 to -0.09mm-1, RMSD from 0.12mm-1 to 0.21mm-1) than with ASiR-V (PFD equal to 0.12 mm-1, RMSD equal to 0.53mm-1), resulting in a sharper image. AUC was always higher with TF than ASIR-V. In average, TF compared to ASiR-V, enabled a radiation dose reduction potential of 7%, 25 % and 33 % for low, medium and high strength respectively. CONCLUSION Compared to ASIR-V, TF at high strength does not impact noise texture and maintains low contrast liver lesions detectability at significant lower dose.
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Affiliation(s)
- D Racine
- Institute of Radiation Physics (IRA), Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue du Grand-Pré 1, 1007 Lausanne, Switzerland.
| | - H G Brat
- Institut de Radiologie de Sion, Groupe 3R, Rue du scex, 2, 1950 Sion, Switzerland
| | - B Dufour
- Institut de Radiologie de Sion, Groupe 3R, Rue du scex, 2, 1950 Sion, Switzerland
| | - J M Steity
- Centre d'imagerie de la Riviera, Groupe 3R, Rue des Moulins 5B, 1800 Vevey, Switzerland
| | - M Hussenot
- GE Medical Systems (Schweiz) AG, Europa-Strasse 31, 8152 Glattbrugg, Switzerland
| | - B Rizk
- Centre d'Imagerie de Fribourg, Groupe 3R, Rue du Centre 10, 1752 Fribourg, Switzerland
| | - D Fournier
- Institut de Radiologie de Sion, Groupe 3R, Rue du scex, 2, 1950 Sion, Switzerland
| | - F Zanca
- Palindromo Consulting, Willem de Croylaan 51, 3000 Leuven, Belgium
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Papadakis AE, Damilakis J. The effect of tube focal spot size and acquisition mode on task-based image quality performance of a GE revolution HD dual energy CT scanner. Phys Med 2021; 86:75-81. [PMID: 34062336 DOI: 10.1016/j.ejmp.2021.05.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 05/05/2021] [Accepted: 05/17/2021] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To assess the task-based performance of images obtained under different focal spot size and acquisition mode on a dual-energy CT scanner. METHODS Axial CT image series of the Catphan phantom were obtained using a tube focus at different sizes. Acquisitions were performed in standard single-energy, high resolution (HR) and dual-energy modes. Images were reconstructed using conventional and high definition (HD) kernels. Task-based transfer function at the 50% level (TTF50%) for teflon, delrin, low density polyethylene (LDPE) and acrylic, as well as image noise and noise texture, were assessed across all focal spots and acquisition modes using Noise Power Spectrum (NPS) analysis. A non-prewhitening mathematical observer model was used to calculate detectability index (dNPW'). RESULTS TTF50% degraded with increasing focal spot size. TTF50% ranged from 0.67 mm-1 for teflon to 0.25 mm-1 for acrylic. For standard kernel, image noise and NPS-determined average spatial frequency were 8.3 HU and 0.29 mm-1, respectively in single-energy, 12.0 HU and 0.37 mm-1 in HR, and 7.9 HU and 0.26 mm-1 in dual-energy mode. For standard kernel, dNPW' was 61 in single-energy and HR mode and reduced to 56 in dual-energy mode. CONCLUSIONS The task-based image quality assessment metrics have shown that spatial resolution is higher for higher image contrast materials and detectability is higher in the standard single-energy mode compared to HR and dual-energy mode. The results of the current study provide CT operators the required knowledge to characterize their CT system towards the optimization of its clinical performance.
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Affiliation(s)
- Antonios E Papadakis
- Medical Physics Department, University General Hospital of Heraklion, Stavrakia 71110, Crete, Greece.
| | - John Damilakis
- Medical Physics Department, University General Hospital of Heraklion, Stavrakia 71110, Crete, Greece
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Radiation Dose to the Fetus From Computed Tomography of Pregnant Patients-Development and Validation of a Web-Based Tool. Invest Radiol 2021; 55:762-768. [PMID: 32604386 DOI: 10.1097/rli.0000000000000701] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Estimations of radiation dose absorbed by the fetus from computed tomography (CT) in pregnant patients is mandatory, but currently available methods are not feasible in clinical routine. The aims of this study were to develop and validate a tool for assessment of fetal dose from CT of pregnant patients and to develop a user-friendly web interface for fast fetal dose calculations. METHODS In the first study part, 750 Monte Carlo (MC) simulations were performed on phantoms representing pregnant patients at various gestational stages. The MC code simulating vendor-independent dose distributions was validated against CT dose index (CTDI) measurements performed on CT scanners of 2 vendors. The volume CTDI-normalized fetal dose values from MC simulations were used for developing the computational algorithm enabling fetal dose assessments from CT of various body regions at different exposure settings. In the institutional review board-approved second part, the algorithm was validated against patient-specific MC simulations performed on CT data of 29 pregnant patients (gestational ages 8-35 weeks) who underwent CT. Furthermore, the tool was compared with a commercially available software. A user-friendly web-based interface for fetal dose calculations was created. RESULTS Weighted CTDI values obtained from MC simulations were in excellent agreement with measurements performed on the 2 CT systems (average error, 4%). The median fetal dose from abdominal CT in pregnant patients was 2.7 mGy, showing moderate correlation with maternal perimeter (r = 0.69). The algorithm provided accurate estimates of fetal doses (average error, 11%), being more accurate than the commercially available tool. The web-based interface (www.fetaldose.org) enabling vendor-independent calculations of fetal doses from CT requires the input of gestational age, volume CTDI, tube voltage, and scan region. CONCLUSIONS A tool for fetal dose assessments from CT of pregnant patients was developed and validated being freely available on a user-friendly web interface.
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Euler A, Taslimi T, Eberhard M, Kobe A, Reeve K, Zimmermann A, Krauss A, Gutjahr R, Schmidt B, Alkadhi H. Computed Tomography Angiography of the Aorta-Optimization of Automatic Tube Voltage Selection Settings to Reduce Radiation Dose or Contrast Medium in a Prospective Randomized Trial. Invest Radiol 2021; 56:283-291. [PMID: 33226202 DOI: 10.1097/rli.0000000000000740] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of this study was to compare the image quality of low-kV protocols with optimized automatic tube voltage selection (ATVS) settings to reduce either radiation dose or contrast medium (CM) with that of a reference protocol for computed tomography angiography (CTA) of the thoracoabdominal aorta. MATERIALS AND METHODS In this institutional review board-approved, single-center, prospective randomized controlled trial, 126 patients receiving CTA of the aorta were allocated to one of three computed tomography protocols: (A) reference protocol at 120 kVp and standard weight-adapted CM dose; (B) protocol at 90 kVp, reduced radiation and standard CM dose; and (C) protocol at 90 kVp, standard radiation and reduced CM dose. All three protocols were performed on a third-generation dual-source computed tomography scanner using the semimode of the ATVS system. The image-task-dependent optimization settings of the ATVS (slider level) were adjusted to level 11 (high-contrast task) for protocols A and B and level 3 (low-contrast task) for protocol C. Radiation dose parameters were assessed. The contrast-to-noise ratios (CNRs) of protocols B and C were tested for noninferiority compared with A. Subjective image quality was assessed using a 5-point Likert scale. RESULTS Size-specific dose estimate was 34.3% lower for protocol B compared with A (P < 0.0001). Contrast medium was 20.2% lower for protocol C compared with A (P < 0.0001). Mean CNR in B and C was noninferior to protocol A (CNR of 30.2 ± 7, 33.4 ± 6.7, and 30.5 ± 8.9 for protocols A, B, and C, respectively). There was no significant difference in overall subjective image quality among protocols (4.09 ± 0.21, 4.03 ± 0.19, and 4.08 ± 0.17 for protocols A, B, and C, respectively; P = 0.4). CONCLUSIONS The slider settings of an ATVS system can be adjusted to optimize either radiation dose or CM at noninferior image quality in low-kV CTA of the aorta. This optimization could be used to extend future ATVS algorithms to take clinical risk factors like kidney function of individual patients into account.
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Affiliation(s)
- André Euler
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Tilo Taslimi
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Matthias Eberhard
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Adrian Kobe
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Kelly Reeve
- Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
| | - Alexander Zimmermann
- Department of Vascular Surgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | | | | | - Hatem Alkadhi
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11052047] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The aim of this study is to investigate the impact of CT acquisition parameter setting on organ dose and its influence on image quality metrics in pediatric phantom during CT examination. The study was performed on 64-slice multidetector CT scanner (MDCT) Siemens Definition AS (Siemens Sector Healthcare, Forchheim, Germany) using various CT CAP protocols (P1–P9). Tube potential for P1, P2, and P3 protocols were fixed at 100 kVp while P4, P5, and P6 were fixed at 80 kVp with used of various reference noise values. P7, P8, and P9 were the modification of P1 with changes on slice collimation, pitch factor, and tube current modulation (TCM), respectively. TLD-100 chips were inserted into the phantom slab number 7, 9, 10, 12, 13, and 14 to represent thyroid, lung, liver, stomach, gonads, and skin, respectively. The image quality metrics, signal to noise ratio (SNR) and contrast to noise ratio (CNR) values were obtained from the CT console. As a result, this study indicates a potential reduction in the absorbed dose up to 20% to 50% along with reducing tube voltage, tube current, and increasing the slice collimation. There is no significant difference (p > 0.05) observed between the protocols and image metrics.
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Muhammad N, Sabarudin A, Ismail N, Karim M. A systematic review and meta-analysis of radiation dose exposure from computed tomography examination of thorax-abdomen-pelvic regions among paediatric population. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Barca P, Paolicchi F, Aringhieri G, Palmas F, Marfisi D, Fantacci ME, Caramella D, Giannelli M. A comprehensive assessment of physical image quality of five different scanners for head CT imaging as clinically used at a single hospital centre-A phantom study. PLoS One 2021; 16:e0245374. [PMID: 33444367 PMCID: PMC7808662 DOI: 10.1371/journal.pone.0245374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
Nowadays, given the technological advance in CT imaging and increasing heterogeneity in characteristics of CT scanners, a number of CT scanners with different manufacturers/technologies are often installed in a hospital centre and used by various departments. In this phantom study, a comprehensive assessment of image quality of 5 scanners (from 3 manufacturers and with different models) for head CT imaging, as clinically used at a single hospital centre, was hence carried out. Helical and/or sequential acquisitions of the Catphan-504 phantom were performed, using the scanning protocols (CTDIvol range: 54.7–57.5 mGy) employed by the staff of various Radiology/Neuroradiology departments of our institution for routine head examinations. CT image quality for each scanner/acquisition protocol was assessed through noise level, noise power spectrum (NPS), contrast-to-noise ratio (CNR), modulation transfer function (MTF), low contrast detectability (LCD) and non-uniformity index analyses. Noise values ranged from 3.5 HU to 5.7 HU across scanners/acquisition protocols. NPS curves differed in terms of peak position (range: 0.21–0.30 mm-1). A substantial variation of CNR values with scanner/acquisition protocol was observed for different contrast inserts. The coefficient of variation (standard deviation divided by mean value) of CNR values across scanners/acquisition protocols was 18.3%, 31.4%, 34.2%, 30.4% and 30% for teflon, delrin, LDPE, polystyrene and acrylic insert, respectively. An appreciable difference in MTF curves across scanners/acquisition protocols was revealed, with a coefficient of variation of f50%/f10% of MTF curves across scanners/acquisition protocols of 10.1%/7.4%. A relevant difference in LCD performance of different scanners/acquisition protocols was found. The range of contrast threshold for a typical object size of 3 mm was 3.7–5.8 HU. Moreover, appreciable differences in terms of NUI values (range: 4.1%-8.3%) were found. The analysis of several quality indices showed a non-negligible variability in head CT imaging capabilities across different scanners/acquisition protocols. This highlights the importance of a physical in-depth characterization of image quality for each CT scanner as clinically used, in order to optimize CT imaging procedures.
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Affiliation(s)
- Patrizio Barca
- Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”, Pisa, Italy
| | - Fabio Paolicchi
- Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy
| | - Giacomo Aringhieri
- Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy
| | | | - Daniela Marfisi
- Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”, Pisa, Italy
| | | | - Davide Caramella
- Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy
| | - Marco Giannelli
- Unit of Medical Physics, Pisa University Hospital “Azienda Ospedaliero-Universitaria Pisana”, Pisa, Italy
- * E-mail:
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Abstract
Radiation dose in computed tomography (CT) has become a hot topic due to an upward trend in the number of CT procedures worldwide and the relatively high doses associated with these procedures. The main aim of this review article is to provide an overview of the most frequently used metrics for CT radiation dose characterization, discuss their strengths and limitations, and present patient dose assessment methods. Computed tomography dosimetry is still based on a CT dose index (CTDI) measured using 100-mm-long pencil ionization chambers and standard dosimetry phantoms (CTDI100). This dose index is easily measured but has important limitations. Computed tomography dose index underestimates the dose generated by modern CT scanners with wide beam collimation. Manufacturers should report corrected CTDI values in the consoles of CT systems. The size-specific dose estimate has been proposed to provide an estimate of the average dose at the center of the scan volume along the z-axis of a CT scan. Size-specific dose estimate is based on CTDI and conversion factors and, therefore, its calculation incorporates uncertainties associated with the measurement of CTDI. Moreover, the calculation of size-specific dose estimate is straightforward only when the tube current modulation is not activated and when the patient body diameter does not change considerably along the z-axis of the scan. Effective dose can be used to provide typical patient dose values from CT examinations, compare dose between modalities, and communicate radiogenic risks. In practice, effective dose has been used incorrectly, for example, to characterize a CT procedure as a low-dose examination. Organ or tissue doses, not effective doses, are required for assessing the probability of cancer induction in exposed individuals. Monte Carlo simulation is a powerful technique to estimate organ and tissue dose from CT. However, vendors should make available to the research community the required information to model the imaging process of their CT scanners. Personalized dosimetry based on Monte Carlo simulation and patient models allows accurate organ dose estimation. However, it is not user friendly and fast enough to be applied routinely. Future research efforts should involve the development of advanced artificial intelligence algorithms to overcome drawbacks associated with the current equipment-specific and patient-specific dosimetry.
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Affiliation(s)
- John Damilakis
- Received for publication June 30, 2020; and accepted for publication, after revision, August 18, 2020. From the Department of Medical Physics, School of Medicine, University of Crete, Crete, Greece
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Zhao Y, Li D, Liu Z, Geng X, Zhang T, Xu Y. Comparison of image quality and radiation dose using different pre-ASiR-V and post-ASiR-V levels in coronary computed tomography angiography. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2021; 29:125-134. [PMID: 33164983 DOI: 10.3233/xst-200754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
OBJECTIVE To determine the optimal pre-adaptive and post-adaptive level statistical iterative reconstruction V (ASiR-V) for improving image quality and reducing radiation dose in coronary computed tomography angiography (CCTA). METHODS The study was divided into two parts. In part I, 150 patients for CCTA were prospectively enrolled and randomly divided into 5 groups (A, B, C, D, and E) with progressive scanning from 40% to 80% pre-ASiR-V with 10% intervals and reconstructing with 70% post-ASiR-V. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was assessed using a 5-point scale. The CT dose index volume (CTDIvol) and dose-length product (DLP) of each patient were recorded and the effective radiation dose (ED) was calculated after statistical analysis by optimizing for the best pre-ASiR-V value with the lowest radiation dose while maintaining overall image quality. In part II, the images were reconstructed with the recommended optimal pre-ASiR-V values in part I (D group) and 40%-90% of post-ASiR-V. The reconstruction group (D group) was divided into 6 subgroups (interval 10%, D0:40% post-ASiR-V, D1:50% post - ASiR-V, D2:60% post-ASiR-V, D3:70% post-ASiR-V, D4:80% post-ASiR-V, and D5:90% post-ASiR-V).The SNR and CNR of D0-D5 subgroups were calculated and analyzed using one-way analysis of variance, and the consistency of the subjective scores used the k test. RESULTS There was no significant difference in the SNRs, CNRs, and image quality scores among A, B, C, and D groups (P > 0.05). The SNR, CNR, and image quality scores of the E group were lower than those of the A, B, C, and D groups (P < 0.05). The mean EDs in the B, C, and D groups were reduced by 7.01%, 13.37%, and 18.87%, respectively, when compared with that of the A group. The SNR and CNR of the D4-D5 subgroups were higher than the D0-D3 subgroups, and the image quality scores of the D4 subgroups were higher than the other subgroups (P < 0.05). CONCLUSION The wide-detector combined with 70% pre-ASiR-V and 80% post-ASiR-V significantly reduces the radiation dose of CCTA while maintaining overall image quality as compared with the manufacture's recommendation of 40% pre-ASiR-V.
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Affiliation(s)
- Yongxia Zhao
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Dongxue Li
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Zhichao Liu
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Xue Geng
- Department of Radiology, Baoding No. 2 Hospital, Baoding, China
| | - Tianle Zhang
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
| | - Yize Xu
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, China
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Papadakis AE, Damilakis J. Technical Note: Evaluating automatic tube current modulation in CT using the standard CTDI dosimetry phantom. Med Phys 2020; 48:659-666. [PMID: 33098127 DOI: 10.1002/mp.14551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Accepted: 10/15/2020] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To assess the utility of the standard body CTDI phantom in characterizing the operation scheme of tube current modulation (TCM) systems in CT. METHODS The body CDTI phantom was used to characterize two TCM systems: TCM1 and TCM2 , implemented in scanners from different vendors. The phantom was aligned at the gantry isocenter in two configurations. In configuration A, the facet planes of the phantom were parallel to the patient table, while in configuration B they were vertical to the patient table and parallel to the patient's long axis. Acquisitions were performed using the routine abdominal examination protocol. mA(z) profiles were recorded from images' DICOM header. The water equivalent diameter (dw ) and oval ratio (OR) were calculated as a function of z-axis location. Image noise was defined as the standard deviation (SD) of the mean Hounsfield unit value measured in a region of interest at the center of the phantom's image. Regression analysis was performed to modulated mA and SD vs dw and OR. The spatial concordance between the change in phantom size and change in mA (SCmA ) was calculated as the percent difference in the slope of mA(z) change between the 1st and 2nd half of the phantom. The corresponding spatial concordance between the change in phantom size and change in image noise (SCnoise ) was calculated. RESULTS Modulated mA(z) along the z-axis did not substantially differentiate between configurations A and B. Correlation between ln(mA) and OR was found to be higher compared to correlation between ln(mA) and dw . SCmA was 48% for TCM1 and 33% for TCM2 . The corresponding SCnoise was 29% for TCM1 and 16% for TCM2 . CONCLUSION Apart from routine CT dosimetry evaluations, the standard CTDI phantom positioned in configuration A or B may additionally be used by medical physicists to evaluate the performance of TCM operational characteristics.
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Affiliation(s)
- Antonios E Papadakis
- Medical Physics Department, University Hospital of Heraklion, Stavrakia, Crete, 71110, Greece
| | - John Damilakis
- Medical Physics Department, University of Crete, Stavrakia, Crete, 71110, Greece
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Zhao Y, Geng X, Li D, Zhang T, Xu Y. Application of full-field organ dose modulation on cervical- thoraco-abdominopelvic contrast-enhanced computed tomography. Jpn J Radiol 2020; 39:254-260. [PMID: 33113053 DOI: 10.1007/s11604-020-01056-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/09/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND AND OBJECTIVE To study the radiation dose and image quality on the use of full-field organ dose modulation (ODM) on cervical-thoracic-abdominal-pelvic contrast-enhanced computed tomography (CT) scanning on female chemotherapy patients. METHODS Eighty female chemotherapy patients undergoing cervical-thoracic-abdominal-pelvic contrast-enhanced CT were prospectively enrolled and randomly divided into two groups: group A and group B, each with 40 patients. Full-field ODM technique was used on group A and regular scanning patterns were used on group B. We calculated and recorded the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective scores, mean tube currents of the anterior, left, posterior, and right aspects of the thyroid, breast, and ovary layers of all the images. The CT dose index volume (CTDIvol) and dose-length product (DLP) of each patient were recorded and the effective radiation dose (ED) was calculated. The above data were statistically analyzed. RESULTS There were no statistically significant differences in the SNR, CNR, and image quality scores of the thyroid, breast, and ovary layers of groups A and B during the arterial and venous phases (P > 0.05). The tube current on the anterior, left, posterior, and right aspects of the thyroid, breast, and ovary layers during the arterial and venous phases (thyroid: 324.46 ± 53.2 and 327.97 ± 61.34; breast: 243.13 ± 50.04 and 248.32 ± 60.33; ovary: 332.28 ± 71.50 and 339.78 ± 76.69; respectively) of group A were (statistically) significantly lower than those of group B (thyroid: 407.60 ± 96.81 and 402.73 ± 90.15; breast: 313.00 ± 106.68 and 315.20 ± 106.73; ovary: 457.78 ± 106.56 and 459.63 ± 106.27; respectively) (P < 0.05). The respective mean CTDIvol and DLP in group A were 22% and 24% lower than those of group B. The mean EDs of the neck, chest, and abdominal-pelvic region in group A were 19.3%, 21.4%, and 26.4% lower than those of group B, respectively (P < 0.05). CONCLUSION The use of ODM can reduce radiation dose of female chemotherapy patients undergoing cervical-thoracic-abdominal-pelvic contrast-enhanced CT, especially radiation-sensitive organs, while maintaining overall image quality.
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Affiliation(s)
- Yongxia Zhao
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, 071000, People's Republic of China.
| | - Xue Geng
- Department of Radiology, Baoding No.2 hospital, Baoding, 071000, People's Republic of China
| | - Dongxue Li
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, 071000, People's Republic of China
| | - Tianle Zhang
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, 071000, People's Republic of China
| | - Yize Xu
- Department of Radiology, The Affiliated Hospital of Hebei University, Baoding, 071000, People's Republic of China
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Tailoring Contrast Media Protocols to Varying Tube Voltages in Vascular and Parenchymal CT Imaging: The 10-to-10 Rule. Invest Radiol 2020; 55:673-676. [PMID: 32898358 DOI: 10.1097/rli.0000000000000682] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The latest technical developments in CT have created the possibility for individualized scan protocols at variable kV settings. Lowering tube voltages closer to the K-edge of iodine increases attenuation. However, the latter is also influenced by patient characteristics such as total body weight. To maintain a robust contrast enhancement throughout the patient population in both vascular and parenchymal CT scans, one must adapt the contrast media administration protocols to both the selected kV setting and patient body habitus. This article proposes a simple rule of thumb for how to adapt the contrast media protocol to any kV setting: the 10-to-10 rule.
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Establishment of CTPA Local Diagnostic Reference Levels with Noise Magnitude as a Quality Indicator in a Tertiary Care Hospital. Diagnostics (Basel) 2020; 10:diagnostics10090680. [PMID: 32916913 PMCID: PMC7555305 DOI: 10.3390/diagnostics10090680] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/12/2020] [Accepted: 08/14/2020] [Indexed: 12/16/2022] Open
Abstract
This study aimed to establish the local diagnostic reference levels (LDRLs) of computed tomography pulmonary angiography (CTPA) examinations based on body size with regard to noise magnitude as a quality indicator. The records of 127 patients (55 males and 72 females) who had undergone CTPAs using a 128-slice CT scanner were retrieved. The dose information, scanning acquisition parameters, and patient demographics were recorded in standardized forms. The body size of patients was categorized into three groups based on their anteroposterior body length: P1 (14–19 cm), P2 (19–24 cm), and P3 (24–31 cm), and the radiation dose exposure was statistically compared. The image noise was determined quantitatively by measuring the standard deviation of the region of interest (ROI) at five different arteries—the ascending and descending aorta, pulmonary trunk, and the left and right main pulmonary arteries. We observed that the LDRL values were significantly different between body sizes (p < 0.05), and the median values of the CT dose index volume (CTDIvol) for P1, P2, and P3 were 6.13, 8.3, and 21.40 mGy, respectively. It was noted that the noise reference values were 23.78, 24.26, and 23.97 HU for P1, P2, and P3, respectively, which were not significantly different from each other (p > 0.05). The CTDIvol of 9 mGy and dose length product (DLP) of 329 mGy∙cm in this study were lower than those reported by other studies conducted elsewhere. This study successfully established the LDRLs of a local healthcare institution with the inclusion of the noise magnitude, which is comparable with other established references.
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Muhammad NA, Abdul Karim MK, Abu Hassan H, Ahmad Kamarudin M, Ding Wong JH, Ng KH. Diagnostic Reference Level of Radiation Dose and Image Quality among Paediatric CT Examinations in A Tertiary Hospital in Malaysia. Diagnostics (Basel) 2020; 10:E591. [PMID: 32823818 PMCID: PMC7460376 DOI: 10.3390/diagnostics10080591] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 01/27/2023] Open
Abstract
Pediatrics are more vulnerable to radiation and are prone to dose compared to adults, requiring more attention to computed tomography (CT) optimization. Hence, diagnostic reference levels (DRLs) have been implemented as part of optimization process in order to monitor CT dose and diagnostic quality. The noise index has recently been endorsed to be included as a part of CT optimization in the DRLs report. In this study, we have therefore set local DRLs for pediatric CT examination with a noise index as an indicator of image quality. One thousand one hundred and ninety-two (1192) paediatric patients undergoing CT brain, CT thorax and CT chest-abdomen-pelvis (CAP) examinations were analyzed retrospectively and categorized into four age groups; group 1 (0-1 year), group 2 (1-5 years), group 3 (5-10 years) and group 4 (10-15 years). For each group, data such as the volume-weighted CT dose index (CTDIvol), dose-length product (DLP) and the effective dose (E) were calculated and DRLs for each age group set at 50th percentile were determined. Both CT dose and image noise values between age groups have differed significantly with p-value < 0.05. The highest CTDIvol and DLP values in all age groups with the lowest noise index value reported in the 10-15 age group were found in CT brain examination. In conclusion, there was a significant variation in doses and noise intensity among children of different ages, and the need to change specific parameters to fit the clinical requirement.
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Affiliation(s)
- Nor Azura Muhammad
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.A.M.); (M.A.K.)
| | - Muhammad Khalis Abdul Karim
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.A.M.); (M.A.K.)
- Centre of Diagnostic Nuclear Imaging, Faculty of Medicine, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
| | - Hasyma Abu Hassan
- Department of Imaging, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
| | - Mazliana Ahmad Kamarudin
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; (N.A.M.); (M.A.K.)
| | - Jeannie Hsiu Ding Wong
- Department of Biomedical Imaging, University Malaya Medical Centre, Petaling Jaya 59100, Kuala Lumpur, Malaysia; (J.H.D.W.); (K.H.N.)
| | - Kwan Hoong Ng
- Department of Biomedical Imaging, University Malaya Medical Centre, Petaling Jaya 59100, Kuala Lumpur, Malaysia; (J.H.D.W.); (K.H.N.)
- Department of Medical Imaging and Radiological Sciences, College of Health Sciences, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
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Funama Y, Takahashi H, Goto T, Aoki Y, Yoshida R, Kumagai Y, Awai K. Improving Low-contrast Detectability and Noise Texture Pattern for Computed Tomography Using Iterative Reconstruction Accelerated with Machine Learning Method: A Phantom Study. Acad Radiol 2020; 27:929-936. [PMID: 31918961 DOI: 10.1016/j.acra.2019.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/01/2019] [Accepted: 09/11/2019] [Indexed: 11/15/2022]
Abstract
RATIONALE AND OBJECTIVES To evaluate the performance of iterative reconstruction (IR) and filtered back projection (FBP) images in terms of low-contrast detectability at different radiation doses, IR levels, and slice thickness using the mathematical model observer with a focus on low-contrast detectability. MATERIALS AND METHODS The CCT189 MITA CT IQ Low-Contrast Phantom was used and helical scans were performed using a 64-detector CT scanner. Tube voltage was set at 120 kVp and tube current was adjusted from 45 to 600 mA. Images were reconstructed at slice thicknesses of 0.625 and 5.0 mm with FBP and five types of iterative progressive reconstruction with visual modeling (IPV) algorithms. The noise power spectrum (NPS) and normalized NPS were calculated. To evaluate low-contrast detectability, the model observer with the channelized Hotelling observer model was applied using low-contrast modules in the phantom. RESULTS The NPS and normalized NPS for IPV images had similar curves as that for FBP images. At a slice thickness of 0.625 mm and equivalent radiation dose level, the mean improvement of low-contrast detectability for IPV images was 1.19-2.15-fold greater than FBP images with corresponding noise reduction levels. At equivalent noise levels of 5.0-8.0 HU, low-contrast detectability of the IPVstd2 to IPVstr2 images as almost the same or better than that of the FBP images. However, the detectability of the IPVstr4 image was lower than that of the FBP image (p = 0.02). CONCLUSION Low-contrast detectability of the IPV images was improved with a similar normalized NPS as with FBP images. Furthermore, a radiation reduction of >50% was achieved for the IPV images, while maintaining similar low-contrast detectability.
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Affiliation(s)
- Yoshinori Funama
- Department of Medical Radiation Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto 862-0976, Japan.
| | | | - Taiga Goto
- Hitachi Ltd. Healthcare Business Unit, Kashiwa, Chiba, Japan
| | - Yuko Aoki
- Hitachi Ltd. Healthcare Business Unit, Kashiwa, Chiba, Japan
| | - Ryo Yoshida
- Hitachi Ltd. Healthcare Business Unit, Kashiwa, Chiba, Japan
| | - Yukio Kumagai
- Hitachi Ltd. Healthcare Business Unit, Kashiwa, Chiba, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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Evaluation of an organ-based tube current modulation tool in pediatric CT examinations. Eur Radiol 2020; 30:5728-5737. [PMID: 32435930 PMCID: PMC7476969 DOI: 10.1007/s00330-020-06888-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 03/16/2020] [Accepted: 04/10/2020] [Indexed: 11/26/2022]
Abstract
Objectives To investigate the effect of an organ-based tube current modulation (OTCM) technique on organ absorbed dose and assess image quality in pediatric CT examinations. Methods Four physical anthropomorphic phantoms that represent the average individual as neonate, 1-year-old, 5-year-old, and 10-year-old were used. Standard head and thorax acquisitions were performed with automatic tube current modulation (ATCM) and ATCM+OTCM. Dose calculations were performed by means of Monte Carlo simulations. Radiation dose was measured for superficial and centrally located radiosensitive organs. The angular range of the OTCM exposure window was determined for different tube rotation times (t) by means of a solid-state detector. Image noise was measured as the standard deviation of the Hounsfield unit value in regions of interest drawn at selected anatomical sites. Results ATCM+OTCM resulted in a reduction of radiation dose to all radiosensitive organs. In head, eye lens dose was reduced by up to 13% in ATCM+OTCM compared with ATCM. In thorax, the corresponding reduction for breast dose was up to 10%. The angular range of the OTCM exposure window decreased with t. For t = 0.4 s, the angular range was limited to 74° in head and 135° for thorax. Image noise was significantly increased in ATCM+OTCM acquisitions across most examined phantoms (p < 0.05). Conclusions OTCM reduces radiation dose to exposed radiosensitive organs with the eye lens and breast buds exhibiting the highest dose reduction. The OTCM exposure window is narrowed at short t. An increase in noise is inevitable in images located within the OTCM-activated imaged volume. Key Points • In pediatric CT, organ-based tube current modulation reduces radiation dose to all major primarily exposed radiosensitive organs. • Image noise increases within the organ-based tube current modulation enabled imaged volume. • The angular range of the organ-based tube current modulation low exposure window is reduced with tube rotation time.
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Steuwe A, Thomas C, Kraus B, Bethge OT, Aissa J, Klosterkemper Y, Antoch G, Boos J. Development of size-specific institutional diagnostic reference levels for computed tomography protocols in neck imaging. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:68-82. [PMID: 31604340 DOI: 10.1088/1361-6498/ab4d00] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
PURPOSE To develop size-specific institutional diagnostic reference levels (DRLs) for computed tomography (CT) protocols used in neck CT imaging (cervical spine CT, cervical CT angiography (CTA) and cervical staging CT) and to compare institutional to national DRLs. MATERIALS AND METHODS Cervical CT examinations (spine, n = 609; CTA, n = 505 and staging CT, n = 184) performed between 01/2016 and 06/2017 were included in this retrospective study. For each region and examination, the volumetric CT dose index (CTDIvol) and dose-length product (DLP) were determined and binned into size bins according to patient water-equivalent diameter (dw). Linear regression analysis was performed to calculate size-specific institutional DRLs for CTDIvol and DLP, applying the 75th percentile as the upper limit for institutional DRLs. The mean institutional CTDIvol and DLP were compared to national DRLs (CTDIvol 20 mGy for cervical spine CT (DLP 300 mGycm) and cervical CTA (DLP 600 mGycm), and CTDIvol 15 mGy for cervical staging CT (DLP 330 mGycm)). RESULTS The mean CTDIvol and DLP (±standard deviation) were 15.2 ± 4.1 mGy and 181.5 ± 88.3 mGycm for cervical spine CT; 8.1 ± 4.3 mGy and 280.2 ± 164.3 mGycm for cervical CTA; 8.6 ± 1.9 mGy and 162.8 ± 85.0 mGycm for cervical staging CT. For all CT protocols, there was a linear increase in CTDIvol and DLP with increasing dw. For the CTDIvol, size-specific institutional DRLs increased with dw from 14 to 29 mGy for cervical spine CT, from 5 to 17 mGy for cervical CTA and from 8 to 13 mGy for cervical staging CT. For the DLP, size-specific institutional DRLs increased with dw from 130 to 510 mGycm for cervical spine CT, from 140 to 640 mGycm for cervical CTA and from 140 to 320 mGycm for cervical staging CT. Institutional DRLs were lower than national DRLs by 81% and 67% for cervical spine CT (dw = 17.8 cm), 43% and 51% for cervical CTA (dw = 19.5 cm) and 59% and 53% for cervical staging CT (dw = 18.8 cm) for CTDIvol and DLP, respectively. CONCLUSION Size-specific institutional DRLs were generated for neck CT examinations. The mean institutional CTDIvol and DLP values were well below national DRLs.
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Affiliation(s)
- Andrea Steuwe
- University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, D-40225 Düsseldorf, Germany
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