Radiation Dose Reduction Research Articles

Dosimetric Comparison Between Proton and Photon Radiation Therapies for Pediatric Neuroblastoma

PurposeThe aim of this study is to determine the most beneficial radiation treatment technique for pediatric patients with thoracic and abdominal neuroblastoma (NBL), through a dosimetric comparison between photon Volumetric Modulated Arc Therapy and proton Intensity-Modulated Proton Therapy treatment plans. Materials and MethodsA retrospective analysis was conducted on a multicentre case series of 19 patients with thoracic and/or abdominal NBL who underwent radiation therapy, following the recommendations of the European protocol for high-risk NBL (HR-NBL2/SIOPEN). The prescribed dose was 21.6 Gy in 12 fractions (1.8 Gy/fraction) delivered over the preoperative disease volume. The dose volume histograms were analyzed for each patient, and a Wilcoxon signed-rank test with a significance level of 0.01 was employed to assess statistical differences between the dosimetric parameters investigated. Two homogeneity indices (HI and newHI) were compared to evaluate the uniformity in dose, delivered to the adjacent vertebrae (VBs_Adj). ResultsBoth radiation techniques conform to the protocol regarding CTV/PTV coverage for every location. Proton therapy resulted in statistically significant dose sparing for the heart and lungs in supradiaphragmatic locations and for the contralateral kidney, liver, spleen, and bowel in subdiaphragmatic locations. For both techniques, sparing the non-adjacent vertebrae (VBs_NAdj) results more challenging, although promising results were obtained. Furthermore, the dose delivered to the VBs_Adj was not statistically different, in terms of homogeneity, for the 2 radiation techniques that both met the protocol’s requirements. ConclusionThis dosimetric analysis highlights the potential of protons to reduce radiation dose to healthy tissue. These findings apply to all the investigated patients, regardless of primary tumor location, making proton therapy a valuable option for the treatment of neuroblastoma. However, a multidisciplinary assessment of each case is essential to ensure the selection of the most effective and suitable treatment modality.

Low-dose versus standard-dose normal temporal bone CT in children: a comparison study

ObjectiveTo compare the image quality of normal anatomical structures and radiation dose on low-dose (LDCT) and standard-dose (SDCT) temporal bone CT in children.MethodsThe study included 45 LDCT (80 kV and 130 mAs) and 45 SDCT (120 kV and 170 mAs) scans in children, 1–15 years of age. LDCT and SDCT scans were analyzed on H60s and H70h reconstruction kernels, respectively. Two readers assessed the image quality for 25 anatomical structures, using a 5-point scale. A score of 3 and above was considered “sufficient” and 2 and below was considered “insufficient” image quality. Image noise, contrast, age and size-specific effective doses were calculated.ResultsDespite an increase in image noise on LDCT, image quality remained sufficient for most structures owing to increased image contrast. The median effective dose on LDCT, calculated with age-specific conversion factor, decreased by 72.9% and that calculated with size-specific conversion factor decreased by 81.8% compared to the dose on SDCT.ConclusionLDCT provides comparable image quality for evaluation of temporal bone with significant reduction in radiation dose in children.

Novel Detector Configurations in Cone-Beam CT Systems: A Simulation Study

Cone-beam computed tomography (CBCT) has emerged in recent years as an adequate alternative to mammography and tomosynthesis due to the several advantages over traditional mammography, including its ability to provide 3D images, its reduced radiation dose, and its ability to image dense breasts more effectively and conduct more effective breast compressions, etc. Furthermore, CBCT is capable of providing images with high sensitivity and specificity, allowing a more accurate evaluation, even of dense breasts, where mammography and tomosynthesis may lead to a false diagnosis. Clinical and experimental CBCT systems rely on cesium iodine (CsI:Tl) scintillators for X-ray energy conversion. This study comprises an investigation among different novel CBCT detector technologies, consisting either of scintillators (BGO, LSO:Ce, LYSO:Ce, LuAG:Ce, CaF2:Eu, LaBr3:Ce) or semiconductors (Silicon, CZT) in order to define the optimum detector design for a future experimental setup, dedicated to breast imaging. For this purpose, a micro-CBCT system was adapted, using GATE v9.2.1, consisting of the aforementioned various detection schemes. Two phantom configurations were selected: (a) an aluminum capillary positioned at the center of the field of view in order to calculate the system’s spatial resolution and (b) a breast phantom consisting of spheres of different materials, such that their characteristics are close to the breast composition. Breast phantom contrast-to-noise ratios (CNRs) were extracted from the phantom’s tomographic images. The images were reconstructed with filtered back projection (FBP) and ordered subsets expectation-maximization (OSEM) algorithms. The semiconductors acted satisfactorily in low-density matter, while LYSO:Ce, LaBr3:Ce, and LuAG:Ce presented adequate CNRs for all the different spheres’ densities. The energy converters that are presented in this study were evaluated for their performance against the standard CsI:Tl crystal.

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

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

Photon-Counting Detector Computed Tomography (PCD-CT): A New Era for Cardiovascular Imaging? Current Status and Future Outlooks.

Photon-counting detector computed tomography (PCD-CT) represents a revolutionary new generation of computed tomography (CT) for the imaging of patients with cardiovascular diseases. Since its commercial market introduction in 2021, numerous studies have identified advantages of this new technology in the field of cardiovascular imaging, including improved image quality due to an enhanced contrast-to-noise ratio, superior spatial resolution, reduced artifacts, and a reduced radiation dose. The aim of this narrative review was to discuss the current scientific literature, and to find answers to the question of whether PCD-CT has yet led to a true step-change and significant progress in cardiovascular imaging.

Inter-reader agreement of pancreatic adenocarcinoma resectability assessment with photon counting versus energy integrating detector CT.

To compare the inter-reader agreement of pancreatic adenocarcinoma resectability assessment at pancreatic protocol photon-counting CT (PCCT) with conventional energy-integrating detector CT (EID-CT). A retrospective single institution database search identified all contrast-enhanced pancreatic mass protocol abdominal CT performed at an outpatient facility with both a PCCT and EID-CT from 4/11/2022 to 10/30/2022. Patients without pancreatic adenocarcinoma were excluded. Four fellowship-trained abdominal radiologists, blinded to CT type, independently assessed vascular tumor involvement (uninvolved, abuts ≤ 180°, encases > 180°; celiac, superior mesenteric artery (SMA), common hepatic artery (CHA), superior mesenteric vein (SMV), main portal vein), the presence/absence of metastases, overall tumor resectability (resectable, borderline resectable, locally advanced, metastatic), and diagnostic confidence. Fleiss's kappa was used to calculate inter-reader agreement. CTDIvol was recorded. Radiation dose metrics were compared with a two-sample t-test. A p < .05 indicated statistical significance. 145 patients (71 men, mean[SD] age: 66[9] years) were included. There was substantial inter-reader agreement, for celiac artery, SMA, and SMV involvement at PCCT (kappa = 0.61-0.69) versus moderate agreement at EID-CT (kappa = 0.56-0.59). CHA had substantial inter-reader agreement at both PCCT (kappa = 0.67) and EIDCT (kappa = 0.70). For metastasis identification, radiologists had substantial inter-reader agreement at PCCT (kappa = 0.78) versus moderate agreement at EID-CT (kappa = 0.56). CTDIvol for PCCT and EID-CT were 16.9[7.4]mGy and 29.8[26.6]mGy, respectively (p < .001). There was substantial inter-reader agreement for involvement of 4/5 major peripancreatic vessels (celiac artery, SMA, CHA, and SMV) at PCCT compared with 2/5 for EID-CT. PCCT also afforded substantial inter-reader agreement for metastasis detection versus moderate agreement at EID-CT with statistically significant radiation dose reduction.

Radiation dose reduction of 50% in dynamic myocardial CT perfusion with skipped beat acquisition: a retrospective study.

Dynamic myocardial computed tomography perfusion (CTP) is a novel imaging technique that increases the applicability of CT for cardiac imaging; however, the scanning requires a substantial radiation dose. To investigate the feasibility of dose reduction in dynamic CTP by comparing all-heartbeat acquisitions to periodic skipping of heartbeats. We retrieved imaging data of 38 dynamic CTP patients and created new datasets with every fourth, third or second beat (Skip1:4, Skip1:3, Skip1:2, respectively) removed. Seven observers evaluated the resulting images and perfusion maps for perfusion deficits. The mean blood flow (MBF) in each of the 16 myocardial segments was compared per skipped-beat level, normalized by the respective MBF for the full dose, and averaged across patients. The number of segments/cases whose MBF was <1.0 mL/g/min were counted. Out of 608 segments in 38 cases, the total additional number of false-negative (FN) segments over those present in the full-dose acquisitions and the number of additional false-positive cases were shown as acquisition (segment [%], case): Skip1:4: 7 (1.2%, 1); Skip1:3: 12 (2%, 3), and Skip1:2: 5 (0.8%, 2). The variability in quantitative MBF analysis in the repeated analysis for the reference condition resulted in 8 (1.3%) additional FN segments. The normalized results show a comparable MBF across all segments and patients, with relative mean MBFs as 1.02 ± 0.16, 1.03 ± 0.25, and 1.06 ± 0.30 for the Skip1:4, Skip1:3, and Skip1:2 protocols, respectively. Skipping every second beat acquisition during dynamic myocardial CTP appears feasible and may result in a radiation dose reduction of 50%. Diagnostic performance does not decrease after removing 50% of time points in dynamic sequence.

Rectal Spacer Reduces Gastrointestinal Side Effects of Radiation Post Radical Prostatectomy

Objectives: Our objective was to assess the rate of complications and gastrointestinal adverse effects of rectal spacer insertion for salvage post prostatectomy radiation therapy. Methods: A retrospective observational study was performed. Between September 2018 and March 2022, 64 post-radical prostatectomy patients who were planned for salvage radiation therapy received a rectal spacer. The selected patients were those who had nerve-sparing prostatectomy with intrafascial or interfascial dissections (where Denonvillier’s fascia is retained). Radiation dose to the rectal wall and gastrointestinal symptoms were assessed. Symptoms were graded using the National Cancer Center Institute Common Terminology Criteria for Adverse Events v4.0 grading scheme. A total of 39 patients had pre-spacer planning computer tomography (CT) scans, and the rectal dose before and after the spacer insertion was calculated. Comparisons were made using the Student’s t-test, with a p-value &lt; 0.05 representing statistical significance. Finally, clinicians were surveyed to rate the ease of the procedure using a 5-point Likert scale of 1 to 5 (1: very difficult, 2: difficult, 3: moderate, 4: easy, 5: very easy). Results: A total of 64 patients successfully underwent rectal spacer insertion. The mean age was 64.4 years (standard deviation: 5.7 years). After a median of 14 months’ (range 6 to 35) follow up, acute grade 1 and above gastrointestinal (GI) toxicities were seen in 28% of patients (grade 2 in 1.5%), and late grade 1 and above GI toxicities were seen in 12% of patients (grade 2 in 1.5%). Amongst the 39 patients with pre-spacer planning CT images, the volume of the rectum receiving 60%, 70%, 80%, 90%, and 100% of the prescribed radiation dose was reduced by 25.9%, 34.2%, 35.4%, 43.7%, and 61.7%, respectively. All dose reductions were statistically significant. The procedure was rated as “easy” or “very easy” to perform in 56% of cases. Conclusions: The insertion of a rectal spacer in selected patients undergoing PPRT is feasible and safe and significantly improves rectal wall radiation dosimetry in salvage post prostatectomy radiation therapy. It was accomplished in &gt;95% of patients, increasing vesico-rectal separation from ‘immediate vicinity’ to 11 mm without any post-operative complications in experienced hands. In addition, it achieved significant reduction in rectal radiation doses, leading to low rates of acute and late grade 2 toxicity.

Wasserstein-GAN-based noise reduction for preserving anatomical structures in low-dose CT

The purpose of low-dose computed tomography (LDCT) is to reduce patient's radiation dose. However, LDCT imaging often suffers from low image quality due to computed tomography (CT) noise patterns. While conventional methods such as iterative reconstruction and image processing have been studied to address this issue, their clinical application remains limited due to the degradation of critical anatomical structures. Recently, deep-learning-based noise reduction approaches have shown promising results in improving the image quality of LDCT. Particularly, generative adversarial network (GAN)-based noise reduction methods have produced outstanding results, approaching the quality of normal-dose CT (NDCT) images. In this study, we propose a hybrid framework based on Wasserstein-GAN with the non-subsampled contourlet transform for enhanced noise reduction in LDCT. The aim is to meticulously address CT noise patterns and generate CT images similar to NDCT. We implemented the proposed algorithm and conducted an experiment using clinical abdominal CT datasets to demonstrate its feasibility. According to our results, the proposed method effectively reduced noise components in LDCT images while preserving the anatomical structures of NDCT. This was confirmed through both qualitative and quantitative evaluations. The implications of our findings for clinical practice are significant, as the proposed method can improve the accuracy of LDCT and reduce radiation dose to patients, ultimately enhancing patient safety.

Influence of deep learning image reconstruction algorithm for reducing radiation dose and image noise compared to iterative reconstruction and filtered back projection for head and chest computed tomography examinations: a systematic review.

The most recent advances in Computed Tomography (CT) image reconstruction technology are Deep learning image reconstruction (DLIR) algorithms. Due to drawbacks in Iterative reconstruction (IR) techniques such as negative image texture and nonlinear spatial resolutions, DLIRs are gradually replacing them. However, the potential use of DLIR in Head and Chest CT has to be examined further. Hence, the purpose of the study is to review the influence of DLIR on Radiation dose (RD), Image noise (IN), and outcomes of the studies compared with IR and FBP in Head and Chest CT examinations. We performed a detailed search in PubMed, Scopus, Web of Science, Cochrane Library, and Embase to find the articles reported using DLIR for Head and Chest CT examinations between 2017 to 2023. Data were retrieved from the short-listed studies using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Out of 196 articles searched, 15 articles were included. A total of 1292 sample size was included. 14 articles were rated as high and 1 article as moderate quality. All studies compared DLIR to IR techniques. 5 studies compared DLIR with IR and FBP. The review showed that DLIR improved IQ, and reduced RD and IN for CT Head and Chest examinations. DLIR algorithm have demonstrated a noted enhancement in IQ with reduced IN for CT Head and Chest examinations at lower dose compared with IR and FBP. DLIR showed potential for enhancing patient care by reducing radiation risks and increasing diagnostic accuracy.

Papel de enfermería en el cateterismo cardiaco derecho. Ventajas del acceso venoso periférico

IntroductionPulmonary hypertension (PH) is a serious disease that requires early diagnosis to achieve a better patient prognosis. Right heart catheterization (RHC) has become the main diagnostic test for this disease, measuring the pressures from the right heart chambers invasively, using a catheter placed through venous access. Nursing performance has an important role in RHC through peripheral venous access due to its well-done skills for canalization and knowledge about the management and care of these accesses. RHC performed through peripheral venous access provide advantages over those performed through central venous access. ObjectiveTo analyze the benefits from RHC through peripheral venous access compared to those performed through central venous access, as well as highlighting the role of nursing during this type of procedures. MethodA retrospective, descriptive, and observational study was performed for patients who underwent RHC in our center between January 2019 to January 2023. We analyzed clinical characteristics, access, fluoroscopy parameters, periprocedural complications, and hospital admissions. ResultA total of 115 patients were included. The average age was 65±12 years, with 58.1% of females. Risk stratification of PH was the reason for conducting RHC in 82.9%. The anterocubital veins became the main approach (72.2%), performed by hemodynamics nurses, while the central venous ones composed the rest (27.8%), which were done by cardiology specialized doctors. We observed a significant reduction in radiation dose in RHC via anterocubital route compared to central venous access (4.4Gycm2 vs 12.5Gycm2 [IQR: 4.5]; P<.001), and it does also in fluoroscopy times (2.3minutes vs 4.6minutes [IQR: 2.6]; P<.001). No complications were recorded, independently of the approach. Patients who underwent a scheduled catheterization were discharged more frequently on the same day of the procedure whether a peripheral approach was performed (77.2%, 44 of 57 patients), in comparison with the central one (28.6%) (P=.001). ConclusionsThe RHC is an essential tool for the diagnosis of PH, achieving nursing such an important role for those performed by peripheral venous access. Peripheral venous access provides benefits and advantages like the reduction of radiation exposure and scan times, reduced hospital stay. All this could bring greater comfort, safety and better quality of care to the patient.

Generation model meets swin transformer for unsupervised low-dose CT reconstruction

Computed tomography (CT) has evolved into an indispensable tool for clinical diagnosis. Reducing radiation dose crucially minimizes adverse effects but may introduce noise and artifacts in reconstructed images, affecting diagnostic processes for physicians. Scholars have tackled deep learning training instability by exploring diffusion models. Given the scarcity of clinical data, we propose the unsupervised image domain score generation model (UISG) for low-dose CT reconstruction. During training, normal-dose CT images are utilized as network inputs to train a score-based generative model that captures the prior distribution of CT images. In the iterative reconstruction, the initial CT image is obtained using a filtered back-projection algorithm. Subsequently, diffusion-based prior, high-frequency convolutional sparse coding prior, and data-consistency steps are employed to obtain the high-quality reconstructed image. Given the global characteristics of noise, the score network of the diffusion model utilizes a swin transformer structure to enhance the model’s ability to capture long-range dependencies. Furthermore, convolutional sparse coding is applied exclusively to the high-frequency components of the image, to prevent over-smoothing or the loss of crucial anatomical details during the denoising process. Quantitative and qualitative results indicate that UISG outperforms competing methods in terms of denoising and generalization performance.

Dual-energy Computed Tomography in Coronary Artery Calcium Scoring

Computed tomographic (CT) coronary artery angiography with calcium scoring is crucial in suspecting coronary artery disease (CAD). The routine protocol for CAD radiological investigation involves a precontrast series for calcium scoring and a postcontrast series for investigating structural changes in coronary arteries. This review intends to investigate the feasibility of virtual noncontrast images to replace the true noncontrast (TNC) images in coronary artery calcium scoring to decrease the radiation dose. The current review included articles found in the PubMed database. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for the further evaluation of the articles for inclusion criteria, 25 articles were finally shortlisted for the final review. It is found that the calcium score of coronary arteries estimated by virtual unenhanced images generated by dual-energy CT (DECT) is comparable with that of TNC images. The virtual unehncanced images has the potential to eliminate the need for the TNC series acquisition, thereby reducing the radiation dose. Especially, photon-counting detector-based DECT has excellent potential in the estimation of calcium scores and the reduction in radiation dose. In addition, contrast dose also can be significantly reduced, which is crucial in patients with renal insufficiency. In conclusion, using DECT for CAD investigations significantly reduces both radiation and contrast doses compared to conventional CT scans. This reduction is particularly crucial for patients who require repeated follow-up scans, as it enhances their safety and minimizes potential risks.

The impact of sedation on the quality of initial skeletal surveys performed for suspected physical abuse in children: a comparative two-centre audit

The impact of sedation on the quality of initial skeletal surveys performed for suspected physical abuse in children is not known. To assess whether sedation influenced the number of, reason for and effective dose of repeat radiographs obtained as part of initial skeletal surveys, and their mean examination times. One hundred consecutive antemortem initial skeletal survey examinations performed for suspected physical abuse in children <2 years were retrieved from two tertiary paediatric hospitals: Centre 1, where sedation is not used for initial skeletal survey imaging; and Centre 2, where sedation is used routinely. In total, 4055 radiographic projections were performed, of which 93 (2.3%) were repeats. Comparing centres, there was a significant difference in the total number of repeats (P=0.001) and the number of repeats in children aged <12 months (P=0.008). Mean examination times were significantly shorter in unsedated children (P=0.005), even after outliers were excluded (P=0.002). There was no significant difference between the number of routine projections (P=0.587), incompletely imaged body parts (P=0.254), rotation/suboptimal positioning (P=0.527), repeats in children aged >12 months (P=0.089), routine projections in children aged <12 months (P=0.642) or >12 months (P=0.979) or the effective doses of repeats (P=0.286). There were fewer repeat projections in sedated children and those aged <12 months but examination times were significantly longer. There was no difference in the effective doses of repeated projections. The routine use of sedation is not supported when performing skeletal survey imaging if the primary considerations are reducing radiation dose and examination time.

Unified Noise-aware Network for Low-count PET Denoising with Varying Count Levels.

As PET imaging is accompanied by substantial radiation exposure and cancer risk, reducing radiation dose in PET scans is an important topic. However, low-count PET scans often suffer from high image noise, which can negatively impact image quality and diagnostic performance. Recent advances in deep learning have shown great potential for recovering underlying signal from noisy counterparts. However, neural networks trained on a specific noise level cannot be easily generalized to other noise levels due to different noise amplitude and variances. To obtain optimal denoised results, we may need to train multiple networks using data with different noise levels. But this approach may be infeasible in reality due to limited data availability. Denoising dynamic PET images presents additional challenge due to tracer decay and continuously changing noise levels across dynamic frames. To address these issues, we propose a Unified Noise-aware Network (UNN) that combines multiple sub-networks with varying denoising power to generate optimal denoised results regardless of the input noise levels. Evaluated using large-scale data from two medical centers with different vendors, presented results showed that the UNN can consistently produce promising denoised results regardless of input noise levels, and demonstrate superior performance over networks trained on single noise level data, especially for extremely low-count data.

Hippocampal Avoidance Prophylactic Cranial Irradiation using Helical Tomotherapy in Small Cell Lung Cancer

OBJECTIVE Prophylactic cranial irradiation (PCI) is a standard treatment for small cell lung cancer (SCLC). Reduced radiation doses at the hippocampal region during PCI might protect against neurocognitive decline after radiotherapy (RT). The purpose of this study is to report the outcome of hippocampal avoidance PCI (HA-PCI) in our center. METHODS After the initial treatment of SCLC, patients whose radiographic data confirmed the absence of intracranial metastasis and controlled of the primary disease received HA-PCI. Thai Mental State Examination (TMSE) and bilateral hippocampal volumes were recorded and analyzed using the Wilcoxon Singed Rank test to compare baseline and two time points (3 and 6 months). The two-year overall survival (OS) and brain control rates were estimated using the Kaplan Meier method. RESULTS Between 2018 and 2021, a total of 10 patients were included in the analysis. The median TMSE and bilateral hippocampal volumes showed no statistically significant difference between baseline and 3 and 6 months. Two-year OS and brain control rates were 78.8% and 71.4%, respectively. Three patients developed intracranial relapses after HA-PCI which were located outside the hippocampal region. CONCLUSIONS HA-PCI did not increase intracranial relapse in this study. HA-PCI should be considered as a treatment option which can potentially protect neurocognitive functions.

The application value of a vendor-specific deep learning image reconstruction algorithm in "triple low" head and neck computed tomography angiography.

Head and neck computed tomography angiography (CTA) technology has become the noninvasive imaging method of choice for the diagnosis and long-term follow-up of vascular lesions of the head and neck. However, issues of radiation safety and contrast nephropathy associated with CTA examinations remain concerns. In recent years, deep learning image reconstruction (DLIR) algorithms have been increasingly used in clinical studies, demonstrating their potential for dose optimization. This study aimed to investigate the value of using a DLIR algorithm to reduce radiation and contrast doses in head and neck CTA. A total of 100 patients were prospectively enrolled and randomly divided into two groups. Group A (50 patients) consisted of those who underwent 70-kVp CTA with a low contrast volume and injection rate and who were classified according to the reconstruction algorithm into subgroups A1 [DLIR at high weighting (DLIR-H)], A2 [DLIR at low weighting (DLIR-L)], and A3 [volume-based adaptive statistical iterative reconstruction with 50% weighting (ASIR-V50%)]. Meanwhile, group B (50 patients) consisted of those who underwent standard radiation and contrast doses at 100 kVp with ASIR-V50% reconstruction. The computed tomography (CT) attenuation, background noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality score (SIQS) were statistically compared for several vessels among the four groups. Group A showed significant reductions in contrast dosage, injection rate, and radiation dose of 36.09%, 20.88%, and 47.80%, respectively, compared to group B (all P<0.001). The four groups differed significantly in terms of background noise (all P<0.05) with group A1 having the lowest value. Group A1 also had significantly higher SNR and CNR values compared to group B in all vessels (all P<0.05) except the M1 of the middle cerebral artery for the SNR. Group A1 also had the highest SIQS, followed by the A2, B, and A3 groups. The SIQS showed good agreement between the two reviewers in all groups, with κ values between 0.88 and 1. Compared to the standard-dose protocol using 100 kVp and ASIR-V50%, a protocol of 70 kVp combined with DLIR-H significantly reduces the radiation dose, contrast dose, and injection rate in head and neck CTA while still significantly improving image quality for patients with a standard body size.

Lifelike PixelPrint phantoms for assessing clinical image quality and dose reduction capabilities of a deep learning CT reconstruction algorithm.

Deep learning CT reconstruction (DLR) has become increasingly popular as a method for improving image quality and reducing radiation exposure. Due to their nonlinear nature, these algorithms result in resolution and noise performance which are object-dependent. Therefore, traditional CT phantoms, which lack realistic tissue morphology, have become inadequate for assessing clinical imaging performance. We propose to utilize 3D-printed PixelPrint phantoms, which exhibit lifelike attenuation profiles, textures, and structures, as a better tool for evaluating DLR performance. In this study, we evaluate a DLR algorithm (Precise Image (PI), Philips Healthcare) using a custom PixelPrint lung phantom and perform head-to-head comparisons between DLR, iterative reconstruction, and filtered back projection (FBP) with scans acquired at a broad range of radiation exposures (CTDIvol: 0.5, 1, 2, 4, 6, 9, 12, 15, 19, and 20 mGy). We compared the performance of each resultant image using noise, peak signal to noise ratio (PSNR), structural similarity index (SSIM), feature-based similarity index (FSIM), information theoretic-based statistic similarity measure (ISSM) and universal image quality index (UIQ). Iterative reconstruction at 9 mGy matches the image quality of FBP at 12 mGy (diagnostic reference level) for all metrics, demonstrating a dose reduction capability of 25%. Meanwhile, DLR matches the image quality of diagnostic reference level FBP images at doses between 4 - 9 mGy, demonstrating dose reduction capabilities between 25% and 67%. This study shows that DLR allows for reduced radiation dose compared to both FBP and iterative reconstruction without compromising image quality. Furthermore, PixelPrint phantoms offer more realistic testing conditions compared to traditional phantoms in the evaluation of novel CT technologies. This, in turn, promotes the translation of new technologies, such as DLR, into clinical practice.

A dense and U-shaped transformer with dual-domain multi-loss function for sparse-view CT reconstruction.

CT image reconstruction from sparse-view projections is an important imaging configuration for low-dose CT, as it can reduce radiation dose. However, the CT images reconstructed from sparse-view projections by traditional analytic algorithms suffer from severe sparse artifacts. Therefore, it is of great value to develop advanced methods to suppress these artifacts. In this work, we aim to use a deep learning (DL)-based method to suppress sparse artifacts. Inspired by the good performance of DenseNet and Transformer architecture in computer vision tasks, we propose a Dense U-shaped Transformer (D-U-Transformer) to suppress sparse artifacts. This architecture exploits the advantages of densely connected convolutions in capturing local context and Transformer in modelling long-range dependencies, and applies channel attention to fusion features. Moreover, we design a dual-domain multi-loss function with learned weights for the optimization of the model to further improve image quality. Experimental results of our proposed D-U-Transformer yield performance improvements on the well-known Mayo Clinic LDCT dataset over several representative DL-based models in terms of artifact suppression and image feature preservation. Extensive internal ablation experiments demonstrate the effectiveness of the components in the proposed model for sparse-view computed tomography (SVCT) reconstruction. The proposed method can effectively suppress sparse artifacts and achieve high-precision SVCT reconstruction, thus promoting clinical CT scanning towards low-dose radiation and high-quality imaging. The findings of this work can be applied to denoising and artifact removal tasks in CT and other medical images.

Synthesis and analysis of composite comprising polybutylene succinate (PBS) and iodine contrast media for enhanced X-ray radiation shielding

ABSTRACT Within the field of radiology, safeguarding against radiation is crucial, particularly in diagnostic procedures like X-rays, as radiation exposure holds the potential to harm cellular DNA. Presently, lead serves as the predominant material for radiation shielding. However, its usage raises environmental concerns owing to its toxic properties. The objective of this study is to investigate a radiation shielding alternative to lead and assess its efficacy in protecting against radiation. We examined the radiation absorption properties of material made from a composite of PBS and iodine contrast media in various proportions. Our findings indicate that the shielding material containing 75% iodine have the greatest ability to reduce radiation dose from X-rays but are still less than lead. Moreover, the PBS composite with iodine contrast media proved to be environmentally friendly, flexible, and exhibited excellent shielding performance in mitigating exposure during diagnostic X-ray procedures.