Ultra-low Dose Research Articles

Dose reduction of rituximab in clinical practice: a retrospective cohort study of rheumatoid arthritis patients in low disease activity on rituximab.

To determine the effects of dose reduction of rituximab (RTX) on rheumatoid arthritis (RA) disease activity in clinical practice. Retrospective cohort study of RA patients using RTX, in stable low disease activity (i.e. Disease Activity Score 28-joint count CRP (DAS28-CRP) ≤3.5 for ≥6 consecutive months) and ≥2 DAS28-CRP measurements. We identified three treatment periods: 1) full dose RTX, 2) RTX dose reduction, and 3) stable RTX dose (and interval) after tapering. Linear mixed-model analysis was used to estimate mean DAS28-CRP during these periods. Rituximab use was assessed as the median percentage of the RTX Daily Defined Dose (%DDD) per period, with 1 x 1000 mg/6 months as reference. 387 patients were included in the cohort with a median of 8 DAS28-CRP measurements (Q1-Q3:4-13) available per patient and median follow-up time of 44 months (Q1-Q3: 23-76). 299 patients tapered RTX and entered period 2 at least once, of whom 226 also entered period 3. Mean DAS28-CRP were 2.37 (95% CI: 2.29, 2.44) for period 1, 2.33 (95% CI: 2.25, 2.40) for period 2, and 2.27 (95% CI: 2.18, 2.35) for period 3, the latter significantly lower compared to period 1 (p=0.025). %DDD for the three time periods were 96%, 57% and 49%, respectively. Dose reduction of RTX in clinical practice is effective for many RA patients and leads to relevant dose reduction. Together with other previously proven benefits of ultra-low dose RTX, wider implementation of ultra-low dose RTX in RA patients should be considered.

Activation of peroxymonopulfate by graphene-supported single-atom FeN5 with an ultra-low dose at low temperature: Nonradical mechanism and antibacterial activity

The catalytic activity of single-atom catalysts (SACs) is closely related to the coordination environment of metal center. Here, a new peroxymonosulfate (PMS) activation strategy based on graphitic carbon nitride-supported Fe SACs (FeCN) containing a five-coordinated structure (FeN5) exhibited remarkable catalytic performance towards doxorubicin hydrochloride (DOX) with an ultra-low-dose catalyst (10 mg·L−1) at a low temperature (4 °C). Singlet oxygen (1O2) and high-valent iron-oxo species (HV-Fe)-dominated nonradical processes are responsible for the degradation and rapid inactivation of Escherichia coli (E. coil) and S. aureus. Density functional theory (DFT) calculations demonstrated that the terminal O of PMS adsorbed onto Fe-N5 sites facilitated the subsequent homolysis of the OO bond to genarate 1O2 and HV-Fe. This work not only develops an efficient catalyst by fine-tuning the local coordination environment but also provides an insight into the mechanism of the nonradical-species-mediated PMS process as well as potential application at the device level.

Efficient wastewater disinfection using a novel microwave discharge electrodeless ultraviolet system with ozone at an ultra-low dose

Microwave discharge electrodeless lamp (MDEL) is a novel ultraviolet (UV) light source. Synergistic disinfection using UV light emitted by MDEL (MWUV) coupled with ozone (O3) at an ultra-low dose was investigated. Escherichia coli and Bacillus subtilis were deactivated more effectively by MWUV/O3 than by either MWUV or O3 alone. MWUV/O3 treatment using an O3 concentration of 0.4 mg/L gave an E. coli inactivation rate of 5.52 log. The photoreactivation degree and rate of E. coli were lower after inactivation by MWUV/O3 treatment than after MWUV treatment alone. The maximum photoreactivation rates after the MWUV/O3 and MWUV treatments were 2.90% and 16.08%, respectively. MWUV/O3 disinfection also inhibited dark resurrection of E. coli and gave a maximum dark resurrection rate of 0.0036%. Electron paramagnetic resonance spectroscopy indicated that more hydroxyl radicals were generated during MWUV/O3 treatment. Scanning electron microscopy and laser confocal scanning microscopy observations indicated that O3 played a key role in breaking down the cell structure. MWUV/O3 treatment gave a good disinfection effect on fecal coliform bacteria in actual domestic wastewater. The results indicated that inactivation of bacteria can be more effectively achieved by MWUV treatment with O3.

Anti-epileptic and Neuroprotective Effects of Ultra-low Dose NADPH Oxidase Inhibitor Dextromethorphan on Kainic Acid-induced Chronic Temporal Lobe Epilepsy in Rats.

Neuroinflammation mediated by microglia and oxidative stress play pivotal roles in the development of chronic temporal lobe epilepsy (TLE). We postulated that kainic acid (KA)-Induced status epilepticus triggers microglia-dependent inflammation, leading to neuronal damage, a lowered seizure threshold, and the emergence of spontaneous recurrent seizures (SRS). Extensive evidence from our laboratory suggests that dextromethorphan (DM), even in ultra-low doses, has anti-inflammatory and neuroprotective effects in many animal models of neurodegenerative disease. Our results showed that administration of DM (10 ng/kg per day; subcutaneously via osmotic minipump for 4 weeks) significantly mitigated the residual effects of KA, including the frequency of SRS and seizure susceptibility. In addition, DM-treated rats showed improved cognitive function and reduced hippocampal neuronal loss. We found suppressed microglial activation-mediated neuroinflammation and decreased expression of hippocampal gp91phox and p47phox proteins in KA-induced chronic TLE rats. Notably, even after discontinuation of DM treatment, ultra-low doses of DM continued to confer long-term anti-seizure and neuroprotective effects, which were attributed to the inhibition of microglial NADPH oxidase 2 as revealed by mechanistic studies.

Randomized control trial to compare effects of ultra-low dose (Ethinylestradiol 20 μg or 15 μg) with low dose (Ethinylestradiol 30 μg) hormonal pills on lipid discordance in non-obese PCOS women.

Regular users of hormonal contraceptive pills show marked heterogeneity in metabolic effects with variations in compositions. This might be due to choice of outcome variables for comparison. Total cholesterol-high-density lipoprotein ratio (TC/HDL) discordance with low-density lipoprotein (LDL-C) has now become an established marker of future risk for atherosclerotic cardiovascular disease and stable to variations in user. The present study was a randomized controlled trial to compare prevalence of TC/HDL and LDL discordance among non-obese women with polycystic ovarian syndrome (PCOS) treated with hormonal pills. Women were randomized into three arms, two arms received ultra-low dose pills (Ethinylestradiol [EE] 20 μg with drosperinone 3 mg or EE 15 μg with gestodene 60 μg) and one arm received low dose pill (EE 30 μg with desogestrel 150 μg). The role of baseline participant features and pill composition on discordance was determined. Discordance was observed in more than a quarter of the participants before intervention. After 1 year of treatment, less than a fifth of the participants were discordant. Ultralow-dose pill users had lower discordance, LDL, and TC than low-dose pill users after 1 year of treatment. The random forest, a non-linear classifier, showed the highest accuracy in predicting discordance. The baseline Parameters with the maximal impact on the occurrence of discordance were triglyceride, homeostatic model assessment for insulin resistance, body mass index, and high density lipoprotein. Non-obese PCOS women on ultra-low dose pill have a lower risk of acquiring future atherosclerotic cardiovascular disease.

Crown ether-based porous organic polymer encapsulated Ag2[Fe(CN)5NO] composite towards ultra-low dose efficient sterilization and wound healing application

The exploration of safe and efficient antibiotic-free antimicrobial agents, harboring the capacities of concurrent antibacterial and wound healing, are highly desired to combat the drug-resistance bacteria. In this report, a nanord-like crown ether-based porous organic polymer (CEP-POP) with intrinsic antibacterial activity containing porphyrin unites, was facilely prepared, which was implemented as a carrier to deposit silver nitroprusside nanoparticles (abbreviated as AgNNPs), denoted as CEP-POP-AgNNP. CEP-POP-AgNNP could effectively address the issues of Ag-based bactericide, which not only significantly enhance the stability of Ag-based bactericide, but also greatly reduce the toxicity to normal tissues. Bacteriostatic study demonstrated CEP-POP-AgNNP could function as a broad-spectrum antibacterial agent with superb synergistic bactericidal activity, whose bactericide rate reached 97.7 ± 0.5 % and 90.7 ± 0.5 %, towards E. coli and S. aureus, respectively, at an extremely low inhibitory concentration (5 μg mL−1), far exceeding the as-reported POP-based antimicrobials. Meanwhile, in vivo experiment on mice validated CEP-POP-AgNNP could further enhance the wound healing in synergy with the antibacterial effect. Hence, this novel but simple Ag immobilization strategy paves a new avenue for the rational design of antibiotic-free antimicrobial agents.

HSA shrinkage optimizes the photostability of embedded dyes fundamentally to amplify their efficiency as photothermal materials

Focused on the performance promotion of organic small molecular dyes based photothermal agents via non-chemical modification, we found that heat-assisted binding of human serum albumin (HSA) to the dye causes shrinkage of the protein and encapsulate the dye to form nanoparticles. This revolutionizes the photostability of small molecule dyes which further improves their photothermal conversion efficiency and tumor ablation performance as photothermal agents significantly. In this work, the obtained photothermal agent named HSA-P2-T could accumulate in tumor and induce 22 °C enhancement of the tumor in xenograft models upon ultra-low dose (0.1 W/cm2) laser irradiation, which, as far as we know, is the lowest laser dose used in vivo photothermal therapy. Utilizing HSA-P2-T, we realized tumor ablation upon twice intravenous injections of the nanoparticles and four photothermal treatments.

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

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

Prophylactic ultra-low dose rituximab to maintain remission in relapsing adult minimal change disease.

Prophylactic ultra-low dose rituximab to maintain remission in relapsing adult minimal change disease.

A supramolecular polymer-collagen microparticle slurry for bone regeneration with minimal growth factor

Recombinant bone morphogenetic protein-2 (BMP-2) is a potent osteoinductive growth factor that can promote bone regeneration for challenging skeletal repair and even for ectopic bone formation in spinal fusion procedures. However, serious clinical side effects related to supraphysiological dosing highlight the need for advances in novel biomaterials that can significantly reduce the amount of this biologic. Novel biomaterials could not only reduce clinical side effects but also expand the indications for use of BMP-2, while at the same time lowering the cost of such procedures. To achieve this objective, we have developed a slurry containing a known supramolecular polymer that potentiates BMP-2 signaling and porous collagen microparticles. This slurry exhibits a paste-like consistency that stiffens into an elastic gel upon implantation making it ideal for minimally invasive procedures. We carried out in vivo evaluation of the novel biomaterial in the rabbit posterolateral spine fusion model, and discovered efficacy at unprecedented ultra-low BMP-2 doses (5 μg/implant). This dose reduces the growth factor requirement by more than 100-fold relative to current clinical products. This observation is significant given that spinal fusion involves ectopic bone formation and the rabbit model is known to be predictive of human efficacy. We expect the novel biomaterial can expand BMP-2 indications for difficult cases requiring large volumes of bone formation or involving patients with underlying conditions that compromise bone regeneration.

A comparative study on the use of ultra-low dose computed tomography scans with conventional computed tomography scans for the evaluation of proximal tibia intra-articular fractures

PurposeA rise in the need of preoperative CT assessment of proximal tibial intra-articular fractures has given rise to an increased load of radiation exposure. This comparative study aims at assessing the efficacy of low dose CT scan by collating images of tibial plateau fractures produced by low dose CT scan with that of conventional dose CT scan. Furthermore, the study aims at computing the comprehensive reduction in the effective dosage of radiation when low dose CT scan is employed for assessing these fractures. MethodsThe study comprise of 23 cases of proximal tibial intra-articular fractures (confirmed by initial radiographs). Low-dose CT scan of the injured limb was preceded by conventional dose CT scan for generating images that were assessed and reported independently by five (single blinded) radiologists (using Schatzker's CT based classification). Quantification of fracture was done to compare them statistically. ResultsA sensitivity of 93.94 % and positive predictive value of 93.92 % was observed on comparing images from low dose and conventional dose CT scan. An effective reduction of 89.81 % in overall dosage of radiation exposure was observed. ConclusionNear equal quality images were generated by low dose CT scan as compared to conventional dose CT scan, thereby demonstrating its non-inferiority with an effective reduction of 89.81 % in overall dosage of radiation exposure.

Sensitive, rapid detection of NCOA4-m6A towards precisely quantifying radiation dosage on a Cas13a-Microdroplet platform

Precise quantification of low-dose ionizing radiation is of great significance in protecting people from damage caused by clinical radiotherapy or environmental radiation. Traditional techniques for detecting radiation, however, remain extreme challenges to achieve high sensitivity and speed in quantifying radiation dosage. In this work, we report a Cas13a-Microdroplet platform that enables sensitive detection of ultra-low doses of radiation (0.5 Gy vs. 1 Gy traditional) within 1 h. The micro-platform adopts an ideal, specific radiation-sensitive marker, m6A on NCOA4 gene (NCOA4-m6A) that was first reported in our recent work. Microfluidics of the platform generate uniform microdroplets that encapsulate a CRISPR/Cas13a detection system and NCOA4-m6A target from the whole RNA extraction, achieving 10-fold enhancement in sensitivity and significantly reduced limit of detection (LOD). Systematic mouse models and clinical patient samples demonstrated its superior sensitivity and LOD (0.5 Gy) than traditional qPCR, which show wide potentials in radiation tracking and damage protection.

Dual-layer spectral computed tomography aortography using a seventy-five-percent-reduced iodine dose protocol and multiparameter spectral imaging: comparison with conventional computed tomography imaging.

Computed tomography angiography (CTA) is the recommended diagnostic and follow-up imaging modality for acute aortic dissection (AD). However, the high-contrast medium burden associated with repeated CT aortography follow-ups remains a significant concern. This prospective study aimed to assess whether an ultra-low contrast dose (75% cutoff) aortic CTA protocol on dual-layer spectral CT could achieve comparable image quality with the full dose protocol. We also investigated the image quality of the virtual noncontrast (VNC) images derived from the ultra-low dose protocol. This study included 37 consecutive patients who were referred to aortic CTA from May 2022 to August 2022. The enrolled patients underwent full-dose contrast CTA and ultra-low dose (reduced to 25% of conventional) contrast CTA on dual-layer spectral CT in 1 day. Virtual monochromatic images (VMIs) were reconstructed with 40 and 70 keV. The VNC images were reconstructed for both protocols. Objective image quality evaluation, recorded as signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs), was compared between the groups using 1-way analysis of variance and post hoc analysis with Bonferroni correction. Subjective image quality was also compared between the groups. Finally, VNC images derived from the low-dose (VNClow) and full-dose (VNCfull) protocols were compared to the true noncontrast (TNC) images. Neither CNR nor SNR was lower for the 40-keV images reconstructed from the ultra-low dose group compared to the conventional images. Both were significantly higher than those of the 70-keV images. Regarding subjective image quality, vessel enhancement was not significantly different between the 40-keV VMI and full-dose images [ascending aorta (AAO): 4.37±0.46 vs. 4.57±0.48, P=0.096; brachiocephalic arteries: 4.34±0.45 vs. 4.51±0.49, P=0.152; abdominal aortic side branch: 4.42±0.48 vs. 4.51±0.49, P=0.480]. The VNClow images were similar to the TNC images but significantly different from the VNCfull images (P<0.001). Ultra-low contrast aortic CTA with a 75%-reduced iodine dose using dual-layer spectral CT and the derived VNC achieved image quality comparable to that of conventional CTA and TNC images.

Ultra Low-Dose Radiation for Extranodal Marginal Zone Lymphoma of the Lung

Definitive radiation treatment (RT) for extranodal marginal zone lymphoma (ENMZL) of mucosal associated lymphoid tissue historically involves treatment to 24-30 Gy. There is increasing data supporting the use of ultra-low dose RT as part of a response-adapted approach in the treatment of orbital and gastric ENMZL. With this approach, patients receive initial treatment with 4 Gy, and additional RT is considered for those with persistent or locally progressive disease. However limited data to date assesses the efficacy of 4 Gy in the management of ENMZL of the lung. We performed an IRB-approved retrospective review of 17 patients with ENMZL of the lung treated with 4 Gy between 7/2015 and 12/2022 with response assessed after RT. Clinical/treatment characteristics, response, and toxicity were extracted from medical records. Statistics were performed using Mann-Whitney U and Fisher's Exact Test. Eight patients (47%) were female, 15 (88%) white, and 1 (6%) Hispanic. Median age at RT was 66 (interquartile range (IQR) 59-77). All had disease limited to the lung at diagnosis and 15 had stage IE disease. Four patients (24%) were diagnosed incidentally on screening/surveillance imaging in the absence of symptoms. Sixteen patients received 4 Gy in 2 fractions, while one patient received a single fraction of 4 Gy. Median SUVmax prior to RT was 4.5 (IQR 3.2-7.2). Median planning target volume (PTV) was 74 cc (IQR 47-130cc). Six patients (35%) had respiratory symptoms prior to RT, which improved or resolved in 3 (50%). A larger PTV was associated with improvement in symptoms following RT with a median PTV of 266 cc (IQR 171-402) in those who experienced improvement vs. 64 cc (IQR 42-100) in those who did not (p = 0.032). One patient experienced toxicity following RT with pleuritic chest pain, which resolved with corticosteroids. At a median follow-up of 15 months following RT (IQR 7-43 months), the overall response rate (ORR) was 100% (CR, n = 15; PR, n = 2). Fourteen patients had follow-up PET/CT, of whom 13 had a complete metabolic response (CMR) at a median of 3 months following RT (IQR 3-5 months). Two additional patients had a complete response (CR) on CT while one had a partial response on CT. Achieving a CR was not associated with SUV prior to RT (p = 0.50) or PTV size (p = 0.62). In patients with stage IE disease, the ORR rate was 100% and there have been no distant failures to date. Fifteen of 17 patients were alive at last follow-up; two passed away of unrelated causes (one from Alzheimer's disease and one from recurrent squamous cell carcinoma). Ultra-low dose radiation of 4 Gy is associated with excellent local control in the management of ENMZL of the lung and is very well tolerated. Four Gy was effective for local control and symptom palliation even for larger tumors and is an effective initial therapy as part of a response-adapted approach even in limited stage patients.

Physical characteristics of deep learning-based image processing software in computed tomography: a phantom study.

This study aimed to assess the image characteristics of deep-learning-based image processing software (DLIP; FCT PixelShine, FUJIFILM, Tokyo, Japan) and compare it with filtered back projection (FBP), model-based iterative reconstruction (MBIR), and deep-learning-based reconstruction (DLR). This phantom study assessed the object-specific spatial resolution (task-based transfer function [TTF]), noise characteristics (noise power spectrum [NPS]), and low-contrast detectability (low-contrast object-specific contrast-to-noise ratio [CNRLO]) at three different output doses (standard: 10mGy; low: 3.9mGy; ultralow: 2.0mGy). The processing strength of DLIPFBP with A1, A4, and A9 was compared with those of FBP, MBIR, and DLR. The standard dose with high-contrast TTFs of DLIPFBP exceeded that of FBP. Low-contrast TTFs were comparable to or lower than that of FBP. The NPS peak frequency (fP) of DLIPFBP shifts to low spatial frequencies of up to 8.6% at ultralow doses compared to the standard FBP dose. MBIR shifted the most fP compared to FBP-a marked shift of up to 49%. DLIPFBP showed a CNRLO equal to or greater than that of DLR in standard or low doses. In contrast, the CNRLO of the DLIPFBP was equal to or lower than that of the DLR in ultralow doses. DLIPFBP reduced image noise while maintaining a resolution similar to commercially available MBIR and DLR. The slight spatial frequency shift of fP in DLIPFBP contributed to the noise texture degradation suppression. The NPS suppression in the low spatial frequency range effectively improved the low-contrast detectability.

Usefulness of Ag Additional Filter on Image Quality and Radiation Dose for Low-Dose Chest Computed Tomography.

This study aimed to evaluate the effect of a silver (Ag) additional filter on dose characteristics and image quality in low-dose chest computed tomography (CT). A dose evaluation phantom, physical evaluation phantom, and chest phantom were scanned with and without an Ag additional filter. The doses were adjusted so that the displayed the volume CT dose indexes (CTDI vol ) were from 0.3 to 1.6 mGy. For dose characteristics, the spectrum of photon energies and the measured CTDI vol were calculated for each scanning condition. For task-based image quality analysis, task transfer function, noise power spectrum, and system performance were evaluated. Streak artifacts, image noise, and contrast-to-noise ratio were quantified using a chest phantom. With the Ag additional filter, mean energy was 22% higher and the CTDI vol was approximately 30% lower than those without the Ag additional filter. The task transfer function and noise power spectrum with the Ag additional filter were lower than those without the Ag additional filter. The system performance with the Ag additional filter was similar to that without the Ag additional filter. The Ag additional filter reduced streak artifact near the lung apex and image noise in the lung fields. The contrast-to-noise ratio was slightly higher with the Ag additional filter than that without the Ag additional filter. The output dose and spatial resolution with the Ag additional filter were lower than those without the Ag additional filter. However, this filter helped reduce the radiation dose, image noise, and streak artifacts, particularly when scanning at ultralow doses.

Organizational Benefits of Ultra-Low-Dose Chest CT Compared to Chest Radiography in the Emergency Department for the Diagnostic Workup of Community-Acquired Pneumonia: A Real-Life Retrospective Analysis.

Background and Objectives: Chest radiography remains the most frequently used examination in emergency departments (ED) for the diagnosis of community-acquired pneumonia (CAP), despite its poor diagnostic accuracy compared with ultra-low-dose (ULD) chest computed tomography (CT). However, although ULD CT appears to be an attractive alternative to radiography, its organizational impact in ED remains unknown. Our objective was to compare the relevant timepoints in ED management of CT and chest radiography. Materials and Methods: We conducted a retrospective study in two ED of a University Hospital including consecutive patients consulting for a CAP between 1 March 2019 and 29 February 2020 to assess the organizational benefits of ULD chest CT and chest radiography (length of stay (LOS) in the ED, time of clinical decision after imaging). Overlap weights (OW) were used to reduce covariate imbalance between groups. Results: Chest radiography was performed for 1476 patients (mean age: 76 years [63; 86]; 55% men) and ULD chest CT for 133 patients (mean age: 71 [57; 83]; 53% men). In the weighted population with OW, ULD chest CT did not significantly alter the ED LOS compared with chest radiography (11.7 to 12.2; MR 0.96 [0.85; 1.09]), although it did significantly reduce clinical decision time (6.9 and 9.5 h; MR 0.73 [0.59; 0.89]). Conclusion: There is real-life evidence that a strategy with ULD chest CT can be considered to be a relevant approach to replace chest radiography as part of the diagnostic workup for CAP in the ED without increasing ED LOS.

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

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

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

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

Investigating the Small Pixel Effect in Ultra-High Resolution Photon-Counting CT of the Lung.

The aim of this study was to investigate potential benefits of ultra-high resolution (UHR) over standard resolution scan mode in ultra-low dose photon-counting detector CT (PCD-CT) of the lung. Six cadaveric specimens were examined with 5 dose settings using tin prefiltration, each in UHR (120 × 0.2 mm) and standard mode (144 × 0.4 mm), on a first-generation PCD-CT scanner. Image quality was evaluated quantitatively by noise comparisons in the trachea and both main bronchi. In addition, 16 readers (14 radiologists and 2 internal medicine physicians) independently completed a browser-based pairwise forced-choice comparison task for assessment of subjective image quality. The Kendall rank coefficient ( W ) was calculated to assess interrater agreement, and Pearson's correlation coefficient ( r ) was used to analyze the relationship between noise measurements and image quality rankings. Across all dose levels, image noise in UHR mode was lower than in standard mode for scan protocols matched by CTDI vol ( P < 0.001). UHR examinations exhibited noise levels comparable to the next higher dose setting in standard mode ( P ≥ 0.275). Subjective ranking of protocols based on 5760 pairwise tests showed high interrater agreement ( W = 0.99; P ≤ 0.001) with UHR images being preferred by readers in the majority of comparisons. Irrespective of scan mode, a substantial indirect correlation was observed between image noise and subjective image quality ranking ( r = -0.97; P ≤ 0.001). In PCD-CT of the lung, UHR scan mode reduces image noise considerably over standard resolution acquisition. Originating from the smaller detector element size in fan direction, the small pixel effect allows for superior image quality in ultra-low dose examinations with considerable potential for radiation dose reduction.