Marcel Opitz

Photon-counting CT (PCCT) and spectral shaping enable new approaches in pediatric imaging, but the effects of clinically implemented tin-filtered pediatric chest protocols on radiation dose and image noise across image quality levels (IQLs) remain insufficiently characterized. This study compared a clinical Sn100 kVp ultra-high resolution (UHR) protocol with a non-tin-filtered 90 kVp standard-resolution protocol using anthropomorphic pediatric phantoms. Three pediatric phantoms (1, 5, and 10 years) were scanned on a commercial PCCT system across IQLs 1–300 using the clinical Sn100 kVp UHR and non-tin-filtered 90 kVp standard-resolution protocols. Radiation dose and ROI-based image noise in lung parenchyma and bone were recorded. The Sn100 kVp UHR protocol showed lower lung-parenchymal noise across all phantom sizes and IQLs and generally lower bone noise. In the ultra-low-dose range (IQL 1–10), lung-parenchymal noise reductions ranged from 31% to 52% and bone-noise reductions reached 58%. Across most IQLs, the Sn100 kVp UHR protocol was associated with higher radiation dose. At high IQLs, dose plateaus occurred at approximately IQL 150 and 100 in the 5- and 10-year-old phantoms, followed by dose crossovers at approximately IQL 220 and 150, respectively. At very low IQLs, the Sn100 kVp UHR protocol showed a dose advantage up to IQL 5, 4, and 3 in the 1-, 5-, and 10-year-old phantoms, respectively. The Sn100 kVp UHR protocol was associated with lower image noise but was not universally dose-saving compared with the non-tin-filtered 90 kVp standard-resolution protocol. In addition, the observed dose behavior was influenced not only by spectral shaping but also by detector readout mode and protocol-specific technical constraints. These findings may support future pediatric chest PCCT protocol optimization.

Background: The demand for minimally invasive diagnostic techniques for peripheral pulmonary lesions (PPL) is rising. Augmented fluoroscopy (AF) provides real-time guidance by overlaying CT-derived virtual targets onto fluoroscopic images, yet its diagnostic value remains poorly defined. Methods: We retrospectively analyzed 226 PPLs targeting procedures performed with navigational bronchoscopy supplemented by AF and R-EBUS between December 2019 and March 2024. TIVL was assessed across 5 standard planes (posteroanterior, 30 degrees toward, 30 degrees away, 30 degrees clockwise, and 30 degrees counterclockwise). Diagnostic yield was defined according to the ATS/ACCP strict criteria. Multivariable logistic regression identified predictors of diagnostic success. Results: Of the 226 analyzed PPLs, 101 (44.7%) showed no R-EBUS signal. In lesions without an R-EBUS signal, diagnostic yield increased from 0% with ≤1 plane to 42% with ≥4 planes. In multivariable analysis, TIVL in 3 planes was associated with a >5-fold higher likelihood of diagnostic success (OR: 5.57; P P =0.01). Lesions within 16 mm of the point of entry demonstrated stepwise yield improvements up to 89% with ≥4 confirmed planes, while more distant lesions showed no significant benefit. In the ≥3-TIVL-plane subgroup, BMI showed a negative trend toward lower diagnostic yield (OR: 0.92; P =0.059). Conclusion: The number of fluoroscopic planes with confirmed TIVL is a significant determinant of diagnostic yield in AF-guided navigational bronchoscopy, particularly in lesions lacking R-EBUS signals. Multiplane TIVL assessment may enhance diagnostic performance in centers without cone-beam CT or digital tomosynthesis availability.

Image-guided lung biopsies play a key role in diagnosing pulmonary lesions. However, comprehensive safety and efficacy data remain limited. As lung screening expands across Europe, more indeterminate nodules require histologic clarification. This study evaluates technical success, diagnostic yield, and complications based on registry data from the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR). A total of 27559 image-guided lung biopsies from 212 centers (2018–2024) were analyzed. Technical success was defined as verified needle placement and diagnostic yield as adequate histological sampling. Complications were classified by the Society of Interventional Radiology (SIR) criteria. Most biopsies (95.9%) were inpatient. Local anesthesia was used in 97.5% of cases. CT guidance was used in 99.4% of cases. Technical success was 97.7%, and the diagnostic yield was 94.3%. Inpatient procedures showed slightly higher technical success rates (97.8% vs. 96.8%, p = 0.032), while the diagnostic yield was similar (94.3% vs. 92.9%, p = 0.063). Overall complications occurred in 19.4% of cases, major complications in 4.9% of cases and mortality in 0.06%. Coagulation disorders increased risk. Image-guided lung biopsies are effective, with high success and diagnostic yield. However, complication rates were substantial, with nearly 20% overall and 5% major events. Careful patient selection and individualized risk stratification are essential to optimize procedural safety.

The effect of iodine preparation concentration on vascular attenuation during computed tomography angiography (CTA) is a topic of controversy. Iodine-based contrast media (CM) formulations are used in different iodine preparation concentrations and, accordingly, their viscosity varies considerably. This study aimed to investigate the influence of CM formulations with different iodine preparation concentrations on image quality under conditions of a constant iodine dose and constant iodine delivery rate (IDR) in low-dose, low-kVp thoracoabdominal CTA using a standardized animal model. A cohort of six healthy Göttingen minipigs underwent three low-dose CTA scans (90 kV, CTDIvol = 1.7 ± 0.5 mGy) using three CM formulations with different iodine preparation concentrations (300, 370, and 400 mgI/mL). All formulations were injected at a constant IDR of 1.3 gI/s and at a constant total iodine dose of 252 mgI/kg in a randomized sequence. Quantitative image quality was assessed using contrast-to-noise ratio (CNR) and image similarity metrics. Subjective image quality was evaluated by two experienced radiologists using a 5-point Likert scale. No significant differences in CNR were observed between the CM formulations (300 mgI/mL = 15.6 ± 2.8, 370 mgI/mL= 15.0 ± 3.8, 400 mgI/mL = 15.0 ± 4.9). The subjective image quality evaluations revealed no significant differences between the groups, except for a slight tendency towards higher ratings for the 300 mgI/mL formulation for sharpness (300 mgI/mL=5 (4.3–5), 370 mgI/mL = 4 (4–5), 400 mgI/mL = 4 (4–5)) and diagnostic acceptability (300 mgI/mL = 4 (3–4), 370 mgI/mL = 3.5 (3–4), 400 mgI/mL = 3.5 (2.3–4)). Under the investigated conditions of constant iodine delivery rate and constant iodine dose, CM formulations with iodine preparation concentrations ranging from 300 to 400 mgI/mL do not lead to significant differences in objective or subjective image quality in low-dose, low-kVp CTA. These findings represent a proof-of-concept under controlled experimental conditions.

Photon-counting computed tomography (PCCT) offers new possibilities for optimizing image quality while reducing radiation dose. However, the influence of acquisition parameters such as tube voltage and spectral shaping with tin filtration on chest imaging remains insufficiently understood. Adult male and female anthropomorphic phantoms were scanned using a dual-source PCCT system across a broad range of image quality levels (IQL 1–100). Radiation dose and signal-to-noise ratio (SNR) were evaluated for protocols using 120 kVp and 140 kVp without tin filtration, and 100 kVp with tin filtration. The male phantom required a significantly higher tube current and radiation dose than the female, reflecting sex-based attenuation differences. Increasing the tube voltage to 140 kVp raised the radiation dose with minimal SNR improvement. Tin filtration substantially reduced the dose despite a higher mAs, with the radiation dose and tube current plateauing near IQL 80. In the low-dose range (IQL 1–20), tin filtration enabled dose reduction without saturation. Slight SNR trade-offs between bone and mediastinum highlight the need for tissue-specific considerations when optimizing PCCT chest protocols. Sex- and tissue-specific differences with tin filtration and varying tube voltages underscore baseline differences in radiation dose and image quality behavior between representative adult body geometries. These baseline relationships provide a technical foundation for future patient-specific protocol optimization.

Background/Objectives: Analysis of the density and spatial distribution of pulmonary infiltrates of patients with high-grade (≥3) pneumonitis after radiochemotherapy and durvalumab consolidation (RT/CTx + IO) was performed in order to define dosimetric hallmarks of the development of infiltrates following this multimodality treatment. Methods: Consecutive patients treated with RT/CTx + IO for stage III NSCLC were retrospectively reviewed with respect to the occurrence of grade ≥ 3 pneumonitis. Lung infiltrates were contoured on follow-up CT scans acquired around the time of maximum pneumonitis expression. The applied dose distribution was overlaid with the follow-up CT using elastic deformation, and infiltrates were binned according to their density in density strata of 50 HU. The dose and density dependence of partial infiltrate volumes per unit lung volume was analyzed using a mixed fixed and random effect model adjusting for patient, density and dose-dependent random effects. Results: Six patients with grade ≥ 3 pneumonitis were identified from 132 patients treated with RT/CT + IO at a comprehensive cancer center. Partial volumes of lung infiltrates captured by follow-up CT with maximum pneumonitis expression ranged from 15.5 to 60.0% (median 39.8%). A significant, systematic dose–response relationship was found for partial lung infiltrate volumes per dose and density bin. A unimodal density distribution of partial lung infiltrate volumes was also found over the infiltrate density range of −1000 to 100 HU. This was determined using a mixed model that adjusted for random effects (p < 0.0001 for both effects, F-test). There was no interaction effect between systematic dose and infiltrate density dependence of the partial infiltrate volumes. The proportion of infiltrate volumes that are attributable to the systematic dose–response relation amounts to a mean of 16.6% of the total infiltrate volume per patient according to this model. Compared to patients with pneumonitis of grade ≤ 2, patients with high-risk pneumonitis had higher partial infiltrate volumes, particularly in the low-dose regions in five grade dose bins up to 20 Gy (AUC = 1.0, p < 0.0001, likelihood-ratio test). Conclusions: Dose-dependent and -independent partial lung infiltrate volumes were found in patients with high-grade pneumonitis after RT/CTx + IO. These results indicate that pneumonitis involves contributions from both radiochemotherapy-induced and immunotherapy-related mechanisms.

Purpose: The standard modality for the diagnosis of ventriculoperitoneal (VP) shunt failure is the radiographic shunt series (RSS). However, ultra-low dose computed tomography (ULD-CT) may replace RSS. The aim of this study was to compare the radiation doses of RSS and ULD-CT in the diagnosis of mechanical shunt failure in human phantoms including pediatric phantoms and to further reduce the total CT dose by reducing the topogram radiation. Methods: Mechanical VP shunt complications were placed on human phantoms representing ages of 1, 5, 10 and 30 years. RSS and ULD-CT were performed on each phantom with different radiation doses of the topogram with varying tube currents (10, 20, 30, 40 and 50 mAs). Effective doses of RSS and ULD-CT were estimated by using conversion factors. Results: ULD-CT demonstrated lower effective doses than RSS in phantoms representing ages 5, 10 and 30 years, while successfully depicting all mechanical shunt complications. However, higher effective doses were assessed for ULD-CT scans of the 1-year phantom than RSS. The effective doses for RSS and ULD-CT (utilizing 10 mAs topograms), respectively, were estimated as follows: 1-year: 0.056 vs. 0.133 mSv; 5-year: 0.186 vs. 0.123 mSv; 10-year: 0.240 vs. 0.107 mSv; 30-year: 0.641 vs. 0.076 mSv. Conclusion: This study demonstrated ULD-CT as an alternative to RSS for the detection of mechanical VP shunt complications, reducing radiation doses in phantoms equivalent to 5 years of age and older while demonstrating the complications equally to RSS. This may be of clinical interest, especially in children due to the reduction of radiation risks.