Low Radiation Dose Research Articles

Magnetic resonance imaging ultrasonography fusion-guided transforaminal epidural steroid injection: a retrospective cohort.

This study aimed to evaluate the applicability and technical feasibility of magnetic resonance imaging (MRI) and ultrasonography (US) fusion-guided transforaminal epidural steroid injection (TFESI) in patients with lumbar disc herniation (LDH) leading to radiculopathy, who are unresponsive to conservative treatment. This retrospective study included 21 patients aged 18-65 years who underwent MRI-US fusion-guided TFESI for LDH-induced radiculopathy. Patient data, including demographic characteristics, body mass index (BMI), fluoroscopy duration, radiation dose, and procedure success, were analyzed. Success was defined by the contrast-spread pattern during the procedure. Statistical analyses were performed to identify factors predicting procedural success. The MRI-US fusion-guided TFESI procedure was successful in 81% of patients. Successful outcomes were significantly associated with younger age (≤ 56 years, p < 0.001), lower BMI (≤ 28kg/m², p < 0.001), shorter fluoroscopy duration (> 4.9s, p < 0.001), and lower radiation dose (> 3.7 mGy, p < 0.001). A positive correlation was observed between age and radiation dose (p = 0.030), as well as between BMI and radiation dose (p = 0.049). MRI-US fusion-guided TFESI is a feasible and safe technique with a high success rate and low radiation exposure in patients with LDH-induced radiculopathy. Younger age, lower BMI, shorter fluoroscopy duration, and lower radiation dose are significant predictors of procedural success. This technique may enhance spatial orientation during the procedure, potentially improving outcomes particularly in younger patients with lower BMI.

Cytogenetic impact of gamma radiation and its effects on growth, yield and drought tolerance of maize (Zea mays L.).

Maize is the third most important grain crop worldwide after wheat and rice; it is a vital global crop, serving as a key source of food, animal feed, and industrial products, making it essential for food security and economic stability in many countries. Drought stress adversely affects water uptake and can stunt growth, reducing the overall productivity of maize. So, this study was carried out to investigate the cytogenetic effects of gamma radiation and drought stress on maize SC131 genotype, focusing on chromosomal aberrations in seedling root meristems induced by varying doses of gamma irradiation (50, 100, 150, 200, and 250 Gray) and drought stress imposed by 10% polyethylene glycol (PEG). The present study also aims to evaluate the impact of these treatments on growth parameters under a controlled pot experiment. Additionally, molecular polymorphism induced by both gamma irradiation and drought stress was analyzed using Real-Time quantitative PCR techniques for DREB2, ERF, and EF transcription factors. Also, under a field condition experiment, maize plants were subjected to the same gamma irradiation doses and drought stress by reducing the number of irrigations, with subsequent evaluations of yield attributes to assess the overall impact of treatments on plant performance. The study also investigates the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) banding patterns of proteins in grains yielded under the influence of gamma radiation and drought treatments. Findings of the current investigation indicate that the low dose of gamma radiation (50 Gray) not only induces cytogenetic changes but also enhances drought tolerance and improves yield characteristics, suggesting that targeted gamma irradiation could serve as a viable strategy to bolster maize resilience in challenging environmental conditions.

Gantry-free cone-beam CT arthrography for diagnosis of scapholunate ligament injuries: accelerating the preoperative work-up in acute wrist trauma.

Combining fluoroscopy and high-resolution cone-beam CT (CBCT) in a multipurpose scanner without a conventional gantry holds the potential for time-saving in musculoskeletal interventions. This study investigated the performance of gantry-free CBCT arthrography in patients with suspected scapholunate ligament (SLL) tears. Fifty-five patients (29 men, 46.0 ± 15.3 years) who underwent preoperative gantry-free CBCT arthrography between June 2021 and March 2024 were analyzed retrospectively. Three radiologists assessed CBCT arthrograms for tears of the palmar and dorsal SLL segments. Surgical reports served as the reference standard for calculating indicators of diagnostic accuracy. Interreader agreement was tested by computing Krippendorff α. Radiation dose and examination time were recorded. Tears of the palmar and dorsal SLL segment were recorded in 25 (45%) and 6 patients (11%), respectively. CBCT arthrography facilitated good sensitivity (range for all readers: 84-92%) and excellent specificity (93-97%) in the assessment of the palmar SLL. For the dorsal SLL, sensitivity (83-100%) and specificity (96-98%) were even higher. Substantial agreement was determined for both the palmar (α = 0.83, 95% CI: 0.74-0.90) and dorsal SLL (0.84, 0.70-0.95). The mean volume CT dose index for CBCT arthrography was 3.2 ± 1.4 mGy. Not requiring patient repositioning, the median time between fluoroscopy-guided contrast injection and CBCT was 3:05 min (2:31-3:50 min). Gantry-free CBCT arthrography allows for excellent accuracy in the preoperative diagnosis of SLL tears with low radiation dose. The ability to alternate between fluoroscopy and CBCT without repositioning facilitates a "one-stop-shop" approach with short examination time. Question Performing fluoroscopy-guided arthrography and high-resolution cone-beam CT without patient repositioning appears advantageous for the preoperative work-up of distal radius fractures with concomitant scapholunate ligament injuries. Findings Gantry-free cone-beam CT arthrography allowed for short examination times and high diagnostic accuracy for either segment of the scapholunate ligament (89-98% versus surgery). Clinical relevance Preoperative assessment of scapholunate instability influences treatment since surgeons can reduce radius fractures and perform osteosynthesis via a dorsal portal to simultaneously stabilize the scapholunate compartment or use an additional dorsal access route for ligament suture and transfixation.

CT-based migration analysis of a tibial component compared to radiostereometric analysis : one-year results of a prospective single-group implant safety study.

Radiostereometric analysis (RSA) is considered the gold standard for in vivo migration analysis, but CT-based alternatives show comparable results in the shoulder and hip. We have previously validated a CT-based migration analysis method (CTMA) in a knee phantom compared to RSA. In this study, we validated the method in patients undergoing total knee arthroplasty (TKA). Our primary outcome measure was the difference in maximum total point motion (MTPM) between the differing methods. A total of 31 patients were prospectively studied having undergone an uncemented medial pivot knee TKA. Migrations were measured up to 12 months with marker-based and model-based RSA, and CT-RSA. Mean precision data for MTPM were 0.27 mm (SD 0.09) for marker-based RSA, 0.37 mm (SD 0.26) for model-based RSA, and 0.25 mm (SD 0.11) for CTMA. CTMA was as precise as both RSA methods (p = 0.845 and p = 0.156). At three months, MTPM showed a mean of 0.66 mm (95% CI 0.52 to 0.81) for marker-based RSA, 0.79 (95% CI 0.64 to 0.94) for model-based RSA, and 0.59 (95% CI 0.47 to 0.72) for CTMA. There was no difference between CTMA and marker-based RSA (p = 0.400), but CTMA showed lower migration than model-based RSA (p = 0.019). At 12 months, MTPM was 1.03 (95% CI 0.79 to 1.26) for marker-based RSA, 1.02 (95% CI 0.79 to 1.25) for model-based RSA, and 0.71 (95% CI 0.48 to 0.94) for CTMA. MTPM for CTMA was lower than both RSA methods (p < 0.001). Differences between migration increased between the methods from three to 12 months. Mean effective radiation doses per examination were 0.016 mSv (RSA) and 0.069 mSv (CT). Imaging time for performing RSA radiographs was 17 minutes 26 seconds (SD 7 mins 9 sec) and 4 minutes 24 seconds (SD 2 mins 3 sec) for CT. No difference in precision was found between CTMA and marker- or model-based RSA, but CTMA shows lower migration values of the tibial component at 12 months. CTMA can be used with low effective radiation doses, and CT image acquisition is faster to perform than RSA methods and may be suitable for use in ordinary clinical settings.

Abstract 29: Non-gated Dual-source Photon-counting CT Angiography Can Detect Cardioembolic Sources Of Acute Ischemic Stroke At The Primary Investigation: A Retrospective Consecutive Cohort Study

Introduction: Early identification of the etiology of ischemic stroke is crucial for secondary prevention. Recent publications on dedicated ECG-gated cardiac CT showcase the potential to detect sources of cardiac embolism. Photon-counting CT (PCCT) uses semiconductors to convert X-ray photons into electrical signals directly. This allows for improved image quality and lower radiation dose compared to conventional CT. Exploiting PCCT technology with a high-pitch dual-source image acquisition may render an exceptionally high temporal resolution. We hypothesized that non-ECG-gated high-pitch dual-source PCCT angiography from the diaphragm to the brain might provide added clinical value in detecting cardiac stroke sources during initial stroke imaging while maintaining optimal brain and neck image quality. Methods: Consecutive patients with a clinical suspicion of acute stroke imaged with a PCCT system between October 4 th , 2023 and April 13 th , 2024 at a Swedish comprehensive stroke center were included. Diaphragm to brain coverage was obtained in an acquisition time of 1.3 seconds; on average, yielding a dose-length product of 360 mGy*cm for the study participants (2.34 mSv). Image quality was graded using a 4-point Likert scale. Images were assessed for cardiac stroke sources. Where available, reference standard echocardiography results were collected. Results: Of 249 consecutive stroke investigations, 193 included cardiothoracic imaging, which constituted the study population. 126 scans (65.3%) were cases with imaging confirmed ischemic stroke. The median age was 74 (IQR, 61-81) years, 99 were male (51.3%). In total, 39.4% underwent follow-up echocardiography. Image quality of the heart was excellent in 19 scans (9.8%) good in 97 (50.3%), moderate in 72 (37.3%), and poor in 5 scans (2.6%). Fourteen (7.3%) certain or probable interatrial septal defects were found in the study population. In the imaging-confirmed ischemic stroke subgroup, six certain or probable cardiac thrombi were found (4.8%). Additionally, a possible cardiac thrombus was found in 31 instances (24.6%). Three aortic valve vegetations were found (2.4%), all confirmed by echocardiography. Conclusions: Non-ECG-gated high-pitch dual-source PCCT angiography typically provides images of high quality, at virtually no time expense while maintaining a reasonably low radiation exposure. Non-gated PCCT angiography is a promising technique to be used as a primary screening method for cardioembolic stroke.

Potential for reduction of radiation dose in the assessment of the lead orientation in directional deep brain stimulation electrodes.

Directional deep brain stimulation (dDBS) relies on electrodes steering the stimulation field in a specific direction. Post implantation, however, the intended and real orientation of the lead frequently deviates e.g. due to torque of the electrode. The orientation is assessed by postoperative imaging such as C-arm cone-beam CT (CBCT) using 3D rotational fluoroscopy and multi-slice CT (MSCT). The objective is to determine the effect of different X-ray systems such as CBCT and MSCT, and scan acquisition parameters on effective radiation doses. We retrospectively investigated the dose area product (DAP) and dose length product (DLP) of patients who underwent both CBCT and MSCT after dDBS surgery. These metrics were then converted into the effective dose by established conversion coefficients. For CBCT, the feasible dose optimization by collimation was virtually assessed. Univariate analysis was performed to determine differences. Among 88 patients median effective dose was 0.20±0.07mSv in CBCT and 2.11±0.33mSv in MSCT (p<0.001). The field of view (FOV) in CBCT can be collimated in craniocaudal orientation by 33.6% and mediolaterally by 60.8%. This optimized collimation implies an effective dose reduction of 76% (p<0.001). Comparison of the effective dose of MSCT vs. CBCT revealed a significant dose reduction by 90.3% (p<0.001), whereas optimal collimation by 97.7% (p<0.001). For assessment of dDBS orientation, CBCT had significantly lower radiation doses compared to MSCT. Optimized collimation in CBCT allows for a further substantial dose reduction. Moreover, the proposed approach is applicable on other neuroimaging procedures such as 3D visualization of treated intracranial aneurysm.

Optimisation of low and ultra-low dose scanning protocols for ultra-extended field of view PET in a real-world clinical setting

True total-body and extended axial field-of-view (AFOV) PET/CT with 1m or more of body coverage are now commercially available and dramatically increase system sensitivity over conventional AFOV PET/CT. The Siemens Biograph Vision Quadra (Quadra), with an AFOV of 106cm, potentially allows use of significantly lower administered radiopharmaceuticals as well as reduced scan times. The aim of this study was to optimise acquisition protocols for routine clinical imaging with FDG on the Quadra the prioritisation of reduced activity given physical infrastructure constraints in our facility. Low-dose (1 MBq/kg) and ultra-low dose (0.5 MBq/g) cohorts, each of 20 patients were scanned in a single bed position for 10 and 15 min respectively with list-mode data acquisition. These data were then reconstructed simulating progressively shorter acquisition times down to 30 s and 1 min, respectively and then reviewed by 2 experienced PET readers who selected the shortest optimal and minimal acquisition durations based on personal preferences. Quantitative analysis was also performed of image noise to assess how this correlated with qualitative preferences. At the consensus minimum acquisition durations at both dosing levels, the coefficient of variance in the liver as a measure of image noise was 10% or less and there was minimal reduction in this measure between the optimal and longest acquisition durations. These data support the reduction in both administered activity and scan acquisition times for routine clinical FDG PET/CT on the Quadra providing efficient workflows and low radiation doses to staff and patients, while achieving high quality images.

Assessing fetal radiation dose from iodine-125 seeds in pregnant breast cancer patients: an updated model

Objective.The treatment of breast cancer during pregnancy requires careful consideration of consequences for both maternal and fetal health. In non-pregnant patients, the use of radioactive iodine-125 (125I)-seeds is standard practice for localising non-palpable breast tumors before breast-conserving surgery. However, the use of125I-seeds in pregnant patients has been avoided due to concerns about fetal radiation exposure.Approach.In this study a mathematical model was developed to estimate the fetal absorbed dose based on several factors: the radioactivity of the125I-seed, the duration of implantation, and the distance between the125I-seed and fetus as a function of maternal anatomy, gestational age, and fetal development. Three scenarios, representing a range of maternal and fetal anatomy, were evaluated, including a worst-case scenario from a radiation safety perspective.Main results.The results show that the fetal absorbed dose varies across the three scenarios, with ranges of 0.0-0.4 mGy, 0.0-1.0 mGy, and 0.0-1.6 mGy, depending on when the125I-seed was implanted and when it was removed. These dose ranges are similar to conventional diagnostic x-ray scans. The maximum calculated absorbed dose (1.6 mGy) is unlikely to be reached in practice and is well below the 100 mGy threshold associated with possible fetal malformations. The associated theoretical cancer risk increase (0.016%) is minimal.Significance.The use of125I-seeds as localisation method of breast tumors in pregnant patients results in low fetal radiation doses and should not be avoided due to dose concerns.

Central Nervous System Response Against Ionizing Radiation Exposure: Cellular, Biochemical, and Molecular Perspectives.

Gamma radiation is known to induce several detrimental effects on the nervous system. The hippocampus region, specifically the dentate gyrus (DG) and subventricular zone (SVZ), have been identified as a radiation-sensitive neurogenic niche. Radiation alters the endogenous redox status of neural stem cells (NSCs) and other proliferative cells, especially in the hippocampus region, leading to oxidative stress, neuroinflammation, and cell death. Planned (i.e., radiotherapy of brain tumor patients) or unplanned radiation exposure (i.e., accidental radiation exposure) can induce nonspecific damage to neuronal tissues, resulting in chronic or acute radiation syndrome. Although anatomical alterations in the neuronal tissues have been reported at higher doses of gamma radiation, biochemical and molecular perturbations may be evident even at much lower radiation doses. They may manifest in the form of neuronal deficits and cognitive impairment. In the present review, several molecular events and signaling pathways, such as oxidative stress, neuroinflammation, apoptosis, cognition, neuroplasticity, and neurotoxicity induced in neuronal cells upon ionizing radiation exposure, are reviewed. Furthermore, brain-specific radioprotectors and mitigators that protect normal neuronal cells and tissues against ionizing radiation during radiotherapy of cancer patients or nuclear emergencies are also discussed.

Intraindividual Comparison of Image Quality Between Low-Dose and Ultra-Low-Dose Abdominal CT With Deep Learning Reconstruction and Standard-Dose Abdominal CT Using Dual-Split Scan.

The aim of this study was to intraindividually compare the conspicuity of focal liver lesions (FLLs) between low- and ultra-low-dose computed tomography (CT) with deep learning reconstruction (DLR) and standard-dose CT with model-based iterative reconstruction (MBIR) from a single CT using dual-split scan in patients with suspected liver metastasis via a noninferiority design. This prospective study enrolled participants who met the eligibility criteria at 2 tertiary hospitals in South Korea from June 2022 to January 2023. The criteria included (a) being aged between 20 and 85 years and (b) having suspected or known liver metastases. Dual-source CT scans were conducted, with the standard radiation dose divided in a 2:1 ratio between tubes A and B (67% and 33%, respectively). The voltage settings of 100/120 kVp were selected based on the participant's body mass index (<30 vs ≥30 kg/m2). For image reconstruction, MBIR was utilized for standard-dose (100%) images, whereas DLR was employed for both low-dose (67%) and ultra-low-dose (33%) images. Three radiologists independently evaluated FLL conspicuity, the probability of metastasis, and subjective image quality using a 5-point Likert scale, in addition to quantitative signal-to-noise and contrast-to-noise ratios. The noninferiority margins were set at -0.5 for conspicuity and -0.1 for detection. One hundred thirty-three participants (male = 58, mean body mass index = 23.0 ± 3.4 kg/m2) were included in the analysis. The low- and ultra-low- dose had a lower radiation dose than the standard-dose (median CT dose index volume: 3.75, 1.87 vs 5.62 mGy, respectively, in the arterial phase; 3.89, 1.95 vs 5.84 in the portal venous phase, P < 0.001 for all). Median FLL conspicuity was lower in the low- and ultra-low-dose scans compared with the standard-dose (3.0 [interquartile range, IQR: 2.0, 4.0], 3.0 [IQR: 1.0, 4.0] vs 3.0 [IQR: 2.0, 4.0] in the arterial phase; 4.0 [IQR: 1.0, 5.0], 3.0 [IQR: 1.0, 4.0] vs 4.0 [IQR: 2.0, 5.0] in the portal venous phases), yet within the noninferiority margin (P < 0.001 for all). FLL detection was also lower but remained within the margin (lesion detection rate: 0.772 [95% confidence interval, CI: 0.727, 0.812], 0.754 [0.708, 0.795], respectively) compared with the standard-dose (0.810 [95% CI: 0.770, 0.844]). Sensitivity for liver metastasis differed between the standard- (80.6% [95% CI: 76.0, 84.5]), low-, and ultra-low-doses (75.7% [95% CI: 70.2, 80.5], 73.7 [95% CI: 68.3, 78.5], respectively, P < 0.001 for both), whereas specificity was similar (P > 0.05). Low- and ultra-low-dose CT with DLR showed noninferior FLL conspicuity and detection compared with standard-dose CT with MBIR. Caution is needed due to a potential decrease in sensitivity for metastasis (clinicaltrials.gov/ NCT05324046).

Evidence for successful gastric perfusion computed tomography with low-radiation dose.

To investigate how the blood flow analysis changes by varying the radiation dose of gastric perfusion CT (PCT) and to prove that a low-radiation dose of PCT is feasible. 5 Beagle dogs were used in a crossover study with 6 groups of varying radiation doses. Iodixanol was IV administered at 3.0 mL/s, and cine CT was performed for 120 seconds. Blood flow maps were obtained from the acquired images using the maximum slope method. Significant differences in blood flow were observed between 80 kV at 50 mA and 120 kV at 100 mA and between 80 kV at 100 mA and 120 kV at 100 mA. Visual noise from the low tube current technique was absent in all color maps. In gastric PCT, blood flow was calculated to be lower with imaging at a low-radiation dose than at a high-radiation dose. By considering that blood flow values change depending on the radiation dose, it was indicated that a low-radiation dose of gastric PCT is feasible. These preliminary findings may have clinical applications in ischemic or oncologic gastric disease noninvasively, at low-radiation doses, and in a short time in the future. Since the contrast medium dose for PCT is low, the diagnostic value of CT examinations can be further improved by performing both conventional CT examinations and PCT at the same time.

Effect of head size, head material, and radiation dose on the repeatability of CT-RSA measurements of femoral head penetration.

The risk of early revision of total hip arthroplasty (THA) for polyethylene wear is now low, but there remains a need to perform wear measurements in patients for clinical surveillance. The gold standard of wear measurements has been radiostereometric analysis (RSA), which has limited availability. The use of computed tomography (CT) to perform THA wear measurement was described a decade ago and found to have acceptable accuracy and precision, but high radiation dose was a concern. Additionally, the use of larger femoral head sizes and ceramic femoral heads has risen in the past decade. The objectives of the study were to determine the effect of femoral head size, femoral head material, and lowered radiation dose on femoral head penetration measurement repeatability. A cadaveric hip was implanted with a cementless THA implant system. CT scans were acquired at a conventional radiation dose and at a reduced dose and repeated for a 32mm and 36mm cobalt-chromium femoral heads and a 32mm ceramic femoral head. Apparent translation of the femoral head versus the acetabular cup was measured between the repeated scans using a CT-RSA software, where deviations from zero indicated measurement precision. The mean and standard deviation of translations in all planes was <0.200mm. There was no effect for 3D translation of increasing cobalt-chromium head size (p=0.2252). Cobalt-chromium heads had superior repeatability compared to ceramic heads at reduced dose (p=0.022), but not at conventional dose (p=0.1265). Further, superior repeatability was achieved with the reduced dose scan for the cobalt-chromium head (p=0.0058), however there was no difference between doses for the ceramic head (p=0.8148). CT-based wear measurement repeatability is excellent and consistent with prior literature even when implementing a larger femoral head, a ceramic femoral head, or reducing radiation dose to 25% of a conventional clinical scan.

Revolutionizing radiotherapy: gold nanoparticles with polyphenol coating as novel enhancers in breast cancer cells—an in vitro study

Breast cancer is the most common cancer among women, with over 1 million new cases and around 400,000 deaths annually worldwide. This makes it a significant and costly global health challenge. Standard treatments like chemotherapy and radiotherapy, often used after mastectomy, show varying effectiveness based on the cancer subtype. Combining these treatments can improve outcomes, though radiotherapy faces limitations such as radiation resistance and low selectivity for malignant cells. Nanotechnologies, especially metallic nanoparticles (NPs), hold promise for enhancing radiotherapy. Gold nanoparticles (AuNPs) are particularly notable due to their high atomic number, which enhances radiation damage through the photoelectric effect. Studies shown that AuNPs can act as effective radiosensitizers, improving tumor damage during radiotherapy increasing the local radiation dose delivered. Traditional AuNPs synthesis methods involve harmful chemicals and extreme conditions, posing health risks. Green synthesis methods using plant extracts offer a safer and more environmentally friendly alternative. This study investigates the synthesis of AuNPs using Laurus nobilis leaf extract and their potential as radiosensitizers in breast carcinoma cell lines (MCF-7). These cells were exposed to varying doses of X-ray irradiation, and the study assessed cell viability, morphological changes and DNA damage. The results showed that green-synthesized AuNPs significantly enhanced the therapeutic effects of radiotherapy at lower radiation doses, indicating their potential as a valuable addition to breast cancer treatment.

Multifunctional Cu3BiS3-BP@PEI Radiosensitizer with Enhanced Reactive Oxygen Species Activity for Multimodal Synergistic Therapy.

Development of radiosensitizers with high-energy deposition efficiency, electron transfer, and oxidative stress amplification will help to improve the efficiency of radiotherapy. To overcome the drawbacks of radiotherapy alone, it is also crucial to design a multifunctional radiosensitizer that simultaneously realizes multimodal treatment and tumor microenvironment modulation. Herein, a multifunctional radiosensitizer based on the Cu3BiS3-BP@PEI nanoheterostructure (NHS) for multimodal cancer treatment is designed. Cu3BiS3-BP@PEI NHS is able to deposit a high radiation dose into cancer cells, enhancing the radiotherapy effect. Due to the heterostructure and the synergistic effect of Cu3BiS3 and black phosphorus (BP), significantly boosted 1O2 and •OH generation is obtained under X-ray irradiation, which is promising for extremely efficient radiodynamic therapy. More importantly, the acidic tumor microenvironment (TME) can induce the cycle conversion of Cu2+ to Cu+, oxidizing glutathione (GSH) and catalyzing intracellular overproduction of H2O2 into highly toxic •OH, which thus further enhances reactive oxygen species (ROS) production and reduces GSH-associated radioresistance. Furthermore, Cu3BiS3-BP@PEI NHS has an excellent photothermal effect and can effectively transform light into heat. The outcomes of the in vitro and in vivo research confirm that the as-prepared Cu3BiS3-BP@PEI NHS has a high synergistic therapeutic efficacy at a low radiation dose. This work provides a viable approach to constructing a multifunctional radiosensitizer for deep tumor treatment with TME-triggered multiple synergistic therapies.

Ultra-low dose dual-layer detector spectral CT for pulmonary nodule screening: image quality and diagnostic performance

ObjectivesTo investigate the image quality and diagnostic performance with ultra-low dose dual-layer detector spectral CT (DLSCT) by various reconstruction techniques for evaluation of pulmonary nodules.Materials and methodsBetween April 2023 and December 2023, patients with suspected pulmonary nodules were prospectively enrolled and underwent regular-dose chest CT (RDCT; 120 kVp/automatic tube current) and ultra-low dose CT (ULDCT; 100 kVp/10 mAs) on a DLSCT scanner. ULDCT was reconstructed with hybrid iterative reconstruction (HIR), electron density map (EDM), and virtual monoenergetic images at 40 keV and 70 keV. Quantitative and qualitative image analysis, nodule detectability, and Lung-RADS evaluation were compared using repeated one-way analysis of variance, Friedman test, and weighted kappa coefficient.ResultsA total of 249 participants (mean age ± standard deviation, 50.0 years ± 12.9; 126 male) with 637 lung nodules were included. ULDCT resulted in a significantly lower mean radiation dose than RDCT (0.3 mSv ± 0.0 vs. 3.6 mSv ± 0.8; p < 0.001). Compared with RDCT, ULDCT EDM showed significantly higher signal-noise-ratio (44.0 ± 77.2 vs. 4.6 ± 6.6; p < 0.001) and contrast-noise-ratio (26.7 ± 17.7 vs. 5.0 ± 4.4; p < 0.001) with qualitative scores ranked higher or equal to the average. Using the regular-dose images as a reference, ULDCT EDM images had a satisfactory nodule detection rate (84.6%) and good inter-observer agreements compared with RDCT (κw > 0.60).ConclusionUltra-low dose dual-layer detector CT with 91.2% radiation dose reduction achieves sufficient image quality and diagnostic performance of pulmonary nodules.Critical relevance statementDual-layer detector spectral CT enables substantial radiation dose reduction without impairing image quality for the follow-up of pulmonary nodules or lung cancer screening.Key PointsRadiation dose is a major concern for patients requiring pulmonary nodules CT screening.Ultra-low dose dual-layer detector spectral CT with 91.2% dose reduction demonstrated satisfactory performance.Dual-layer detector spectral CT has the potential for lung cancer screening and management.Graphical

Enhancing Radiation Therapy Response in Prostate Cancer Through Metabolic Modulation by Mito-Lonidamine: A 1H and 31P Magnetic Resonance Spectroscopy Study.

Radiation therapy (RT) is the cornerstone treatment for prostate cancer; however, it frequently induces gastrointestinal and genitourinary toxicities that substantially diminish the patients' quality of life. While many individuals experience transient side effects, a subset endures persistent, long-term complications. A promising strategy to mitigate these toxicities involves enhancing tumor radiosensitivity, potentially allowing for lower radiation doses. In this context, mito-lonidamine (Mito-LND), an antineoplastic agent targeting the mitochondrial electron transport chain's complexes I and II, emerges as a potential radiosensitizer. This study investigated Mito-LND's capacity to augment RT efficacy and reduce adverse effects through comprehensive in vitro and in vivo assessments using hormone-sensitive and hormone-refractory prostate cancer models. Employing a Seahorse analysis and 1H/31P magnetic resonance spectroscopy (MRS), we observed that Mito-LND selectively suppressed lactate production, decreased intracellular pH, and reduced bioenergetics and oxygen consumption levels within tumor cells. These findings suggest that Mito-LND remodels the tumor microenvironment by inducing acidification, metabolic de-energization, and enhanced oxygenation, thereby sensitizing tumors to RT. Our results underscore the potential of Mito-LND as a therapeutic adjunct in RT to improve patient outcomes and reduce radiation-associated toxicities in early-stage prostate cancer.

Gafchromic Films as a Complementary In-field Dosimetric Tool to Monitor Low Photon Radiation Doses (≤50 mSv).

This study elucidated the radiation response characteristics of a Gafchromic radiochromic film subjected to low photon doses of ≤50 mSv, which corresponds to the annual whole body effective dose limit for radiation workers in Canada. Radiochromic films are investigated for possible use as a complementary tool for the Canadian Armed Forces that can be worn in addition to their existing personal dosimetry to quickly assess personal radiation dose received from radiological hazards without reliance on electronics. The films were exposed to varying photon energies emanating from x-ray generators and radioisotopes, specifically cesium-137, cobalt-60, and americium-241. The resultant radiation-induced film darkening was quantitatively assessed employing three analytical methodologies: net optical density analysis, UV/Visible spectroscopic analysis, and Fourier Transform Infrared spectroscopic analysis. Ideally, a film dosimeter necessitates a pronounced chromatic alteration and the capability to accurately quantify doses ≤50 mSv where net optical density analysis was identified as the optimal modality for interpreting the film darkening into a dose approximation. This new approach established a lower detection threshold of 7.6 mSv for the films when exposed to cesium-137 radiation. Notably, the film exhibited a linear dose response relationship in terms of net optical density; however, a photon energy-dependent variability was observed within the 0-100 mSv dose range. In conclusion, these Gafchromic radiochromic films present a promising candidate for military dosimetry applications. They offer a real-time, visual dose response that can be discerned by military personnel or analyzed using mobile spectroscopic instrumentation. Moreover, these films demonstrate proficiency in the accurate quantification of photon doses ≤50 mSv. Future investigations will evaluate the film's performance under heterogeneous and indeterminate radiation environments, as well as the impact of environmental conditions on the film's performance.

Comprehensive Non-invasive Versus Invasive Approach to Evaluate Cardiac Allograft Vasculopathy in Heart Transplantation: The CCTA-HTx Study.

Coronary computed tomography angiography (CCTA) is emerging as a valuable tool for noninvasive surveillance of cardiac allograft vasculopathy (CAV) in patients with heart transplant (HTx). We assessed the diagnostic performance of a comprehensive CCTA-based approach compared with the invasive reference, which includes invasive coronary angiography, intravascular ultrasound, and fractional flow reserve, for detecting CAV. This was a multicenter prospective study including 37 patients with HTx who underwent CCTA, invasive coronary angiography, intravascular ultrasound, and fractional flow reserve. The comprehensive CCTA-based approach included quantitative and qualitative plaque analysis and functional assessment by fractional flow reserve derived from coronary computed tomography. CAV was diagnosed based on invasive coronary angiography (International Society for Heart and Lung Transplantation criteria) and intravascular ultrasound. Univariable logistic regression analysis was performed to test CCTA-derived predictors of CAV. The area under the curve and accuracy indicators were calculated to evaluate the performance and best cutoffs of CCTA predictors of CAV. The median interval between CCTA and HTx was 5 years. Among the 37 recipients, 23 (62.2%) were diagnosed with CAV. The integration of diameter stenosis and plaque morphology (including plaque burden at minimum lumen area >42% and percent atheroma volume >23%) at CCTA yielded the highest diagnostic performance (accuracy, 84%; sensitivity, 83%; specificity, 86%). The integration of ∆fractional flow reserve derived from coronary computed tomography trans-vessel gradient led to increased sensitivity, albeit with decreased specificity and overall accuracy. The noninvasive approach was associated with a lower contrast and radiation dose, compared with the invasive approach. A noninvasive strategy based on CCTA is accurate for managing patients with HTx. CCTA might be considered the preferred imaging modality for annual CAV surveillance after the first year post-HTx.

Characterizing Antimicrobial Effects of Radiation and Antibiotic Interactions on Staphylococcus aureus and Escherichia coli Using MALDI-TOF MS.

Background/Objectives: Antibiotic-resistant bacteria are becoming a major challenge in human and veterinary medicine, as well as in food processing. Methods: In this study, the protein diversity in antibiotic-sensitive and -resistant strains of Staphylococcus aureus and Escherichia coli was investigated by exposing them to varying doses of gamma irradiation, with and without antibiotic presence. Changes in bacterial protein profiles were characterized using MALDI-TOF MS to reveal dose-dependent adaptations and potentiation effects under combined irradiation and antibiotic treatments. Results: The results indicate that MALDI-TOF MS effectively differentiates between sensitive and resistant strains, particularly at lower radiation doses (0, 0.2, and 0.4 kGy), with distinct separation in protein spectra. However, at 0.6 kGy, protein profiles plateaued, suggesting a potential threshold effect in radiation response. In 24-h cultures from irradiated Staphylococcus aureus, significant differences emerged in the resistant strain at 0.6 kGy in the presence of antibiotics, with further generational divergence dependent on initial antibiotic exposure. In the case of the sensitive strain, profiles were notably distinct at the 0.4 and 0.6 kGy doses, revealing dose- and treatment-specific responses. For Escherichia coli, generational differences between resistant and sensitive strains were apparent, though antibiotic effects on protein profiles were limited to the 0.6 kGy dose. Conclusions: The results underscore a potentiation interaction between irradiation and antibiotic exposure, affecting protein diversity and adaptation. Sensitive strains displayed heightened proteomic responses to minor treatment variations, while resistant strains exhibited more stable profiles across conditions. The findings highlight MALDI-TOF MS as a valuable tool in detecting proteomic biomarkers linked to bacterial resistance and stress adaptation.

Optimising (re-)irradiation for locally recurrent head and neck cancer: impact of dose-escalation, salvage surgery, PEG tube and biomarkers on oncological outcomes—a single centre analysis

IntroductionLocoregional recurrence (LR) is common in locally advanced head and neck cancer (HNSCC), posing challenges for treatment. We analysed outcome parameters and toxicities for patients being treated with radiotherapy (RT) for LR-HNSCC and investigated patient and disease related prognostic factors in this prognostically unfavourable group.MethodsThis analysis includes 101 LR-HNSCC patients treated with RT, radio-chemotherapy (RCT) or radio-immunotherapy (RIT) between 2010 and 2018 at a high-volume tertiary centre. Patient characteristics, tumour and treatment details were retrospectively collected. Overall survival (OS), progression-free survival (PFS) and toxicities according to Common Terminology Criteria for Adverse Events (CTCAE) v5.0 were assessed.Results62% of patients were radiotherapy-naïve (initial RT group) while 38% were re-irradiated at site of LR (re-RT group). Median OS for initial RT was 24 months, for re-RT 12 months (p < 0.01). In the RCT subgroup, patients with initial RT had significantly longer OS with 35 months compared to re-RT 12 months (p < 0.05). Patients with UICC grade IV tumours and percutaneous endoscopic gastrostomy (PEG) tube had significantly shorter OS in multivariate analysis: initial RT 13 vs. re-RT 32 months and initial RT 12 vs. re-RT 32 months respectively. Salvage surgery before RT at recurrence was a positive prognostic factor for OS (initial RT 35 vs. re-RT 12 months). Other significant factors for longer OS in univariate analysis included low inflammatory status (Glasgow Prognostic Score 0) and radiation doses ≥ 50 Gy. We detected 37 (15%) ≥ CTCAE Grade 3 events for initial RT and 19 (15%) for re-RT patients.ConclusionIn this analysis, we identified key prognostic factors including PEG tube and inflammation status that could guide treatment decision. Our findings suggest salvage surgery as preferred treatment option with postoperative RT at LR. Adverse events due to re-RT were acceptable. A radiation dose of ≥ 50 Gy should be administered to achieve better outcomes.