Additional Radiation Research Articles

Mandibular chondroblastic type osteosarcoma primarily diagnosed as chondrosarcoma as a result of radiation therapy: a case report

Radiation therapy is a recognized etiological factor for osteomyelitis, osteoradionecrosis and multiple sarcomas such as chondrosarcoma and osteosarcoma. Here we present a case of mandibular chondroblastic type osteosarcoma induced by radiotherapy which was primarily misdiagnosed as chondrosarcoma. A female presented with main complaint of pain at the extraction site following multiple teeth extraction and sequestrectomy on the right lower jaw. Medical history revealed stage IV squamous cell carcinoma of the base of the tongue which was treated by surgical excision, chemotherapy and radiotherapy ten years ago. Four recurring sequestrectomies were performed, but only histological material from the fourth sequestrectomy revealed grade 2 chondrosarcoma. This was followed by resection of the tumour and floor of the mouth, mandibular, lip and facial skin reconstruction and operation material through histology was again confirmed to be grade 2 chondrosarcomas. In a year’s time, pathological nodule in thyroid gland was found on CT, surgery was performed. Operation material now revealed high grade chondroblastic type osteosarcoma and additional radiotherapy and chemotherapy was prescribed. This case illustrated chondrosarcoma and chondroblastic type osteosarcoma as a rare malignant incidence, with diagnostical difficulties and treatment. Differential diagnosis should be considered if no positive changes are observed after the designated therapy as well as importance of immuno histological evaluation. One treated malignancy does not exclude development of another unrelated malignancy.

Radiation Dose Savings Associated with Personalized CT Scan Range in 18F-NaF Bone PET/CT.

A disadvantage of 18F-NaF PET/CT compared with other types of bone scintigraphy is the additional radiation dose from the standard whole-body CT scan for lesion localization and characterization (L/C). This study investigated whether the L/C CT region can be personalized to reduce CT radiation dose, according to uptake in the PET images. Methods: Attenuation-corrected 18F-NaF PET images were reviewed for the clinically required L/C CT range by 1 medical observer and 1 technologist observer in 25 patients with breast cancer scanned before neoadjuvant chemotherapy. For each patient, effective doses were estimated for whole-body L/C CT, personalized L/C CT, and whole-body CT for attenuation correction only. Dose savings for the personalized method incorporating both whole-body CT for attenuation correction and personalized L/C CT were expressed relative to standard whole-body L/C CT. The clinical impact of the personalized method was determined by evaluating whether lesions clinically requiring coverage had been missed from the L/C CT region. Results: Potential dose savings of 43%-54% were estimated for the personalized CT method, according to the observers. From the 25 patients reviewed, the medical observer did not miss any clinically significant lesions from the L/C CT region, whereas the technologist observer missed 2 clinically significant lesions of 61 suggestive lesions identified by medical observer follow-up. Conclusion: Mean CT dose could be reduced by around half in this patient group with personalized CT. Future work should further evaluate whether this method can be implemented in clinical practice without compromising clinical image evaluation.

Navigating the Uncommon: Inguinal Metastasis in Dermatofibrosarcoma Protuberans

Abstract Dermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive soft tissue sarcoma with a low rate of metastasis, affecting around four per million annually. Representing about 1% of sarcomas, often manifests on the trunk or proximal extremities. Most cases are low-grade, but some have a high-grade fibrosarcomatous component, which is linked to a higher risk of recurrence and metastasis. Here, we present a 55-year-old male with DFSP, initially presenting as a non-healing ulcer on his foot. Despite surgical excision, radiotherapy, and chemotherapy with imatinib, the patient developed a recurrent ulcer and calcaneum involvement, leading to below-knee amputation. One year later, inguinal lymph node metastasis was detected. After inguinal lymph node dissection and additional radiotherapy, the patient showed no further active lesions. This case highlights the rarity of lymph node metastasis in DFSP and the ongoing need for research into optimal management strategies.

Deep learning-based CT-free attenuation correction for cardiac SPECT: a new approach

BackgroundComputed tomography attenuation correction (CTAC) is commonly used in cardiac SPECT imaging to reduce soft-tissue attenuation artifacts. However, CTAC is prone to inaccuracies due to CT artifacts and SPECT-CT mismatch, along with additional radiation exposure to patients. Thus, these limitations have led to increasing interest in CT-free AC, with deep learning (DL) offering promising solutions. We proposed a new DL-based CT-free AC methods for cardiac SPECT.MethodsWe developed a feature alignment attenuation correction network (FA-ACNet) based on the 3D U-Net framework to generate predicted DL-based AC SPECT (Deep AC). The network was trained on 167 cardiac SPECT/CT studies using 5-fold cross validation and tested in an independent testing set (n = 35), with CTAC serving as the reference. During training, multi-scale features from non-attenuation-corrected (NAC) SPECT and CT were processed separately and then aligned with the encoded features from NAC SPECT using adversarial learning and distance metric learning techniques. The performance of FA-ACNet was evaluated using mean square error (MSE), structural similarity index (SSIM) and peak signal-to-noise ratio (PSNR). Additionally, semi-quantitative evaluation of Deep AC images was performed and compared to CTAC using Bland-Altman plots.ResultsFA-ACNet achieved an MSE of 16.94 ± 2.03 × 10− 6, SSIM of 0.9955 ± 0.0006 and PSNR of 43.73 ± 0.50 after 5-fold cross validation. Compared to U-Net, MSE and PSNR improved by aligning multi-scale features from NAC SPECT and CT with those from NAC SPECT. In the testing set, FA-ACNet achieved an MSE of 11.98 × 10− 6, SSIM of 0.9976 and PSNR of 45.54. The 95% limits of agreement (LoAs) between the Deep AC and CTAC images for the summed stress/rest scores (SSS/SRS) were [− 2.3, 2.8] and [-1.9,2.1] in the training set and testing set respectively. Changes in perfusion categories were observed in 4.19% and 5.9% of studies assessed for global perfusion scores in the training set and testing set.ConclusionWe propose a novel DL-based CT-free AC approach for cardiac SPECT, which can generate AC images without the need for a CT scan. By leveraging multi-scale features from both NAC SPECT and CT, the performance of CT-free AC is significantly enhanced, offering a promising alternative for future DL-based AC strategies.

Neoadjuvant immunotherapy for locally advanced/metastatic mismatch repair deficient colorectal cancer: A two-year institutional experience.

179 Background: MMRd is a tumour agnostic biomarker predictive of response to immune checkpoint inhibitors (ICIs). Given the poor response to 5-FU based chemotherapy, ICIs are now being explored in early MSI-H CRC. The outcomes on this strategy are limited. Methods: We retrospectively evaluated early outcomes for patients receiving neoadjuvant ICIs for unresectable locally advanced/oligometastatic MMRd colorectal cancer (CRC), where intention of treatment was downstaging to permit curative resection. Following discussion at regional MDT, suitable patients were administered a PD-1 inhibitor 6-weekly until disease progression or improvement rendering suitability for surgical resection (to max of 2 years). Results: From October 2022-September 2024, ten patients with MMRd CRC were commenced on neoadjuvant ICIs. These comprised six right, one left sided colonic and three rectal tumours. Median age at diagnosis was 59 (IQR54–68). Four patients had family history of CRC. One patient had clinical stage II, seven stage III and two patients oligometastatic stage IV disease. All were patients with initially unresectable disease, with potential for curative resection pending response to ICI. Histologically, two tumours were poorly differentiated, two mucinous phenotype and six moderately differentiated adenocarcinomas. BRAF mutation was identified in three patients. None had KRAS mutation. Three rectal cancers received radiotherapy in addition to immunotherapy. Five required a defunctioning stoma either prior to or on ICI. Median follow-up was 12.5 months (IQR7-17). Objective response rate by RECIST 1.1 was 100%, with significant downstaging in 9 of 10 patients. The remaining patient is early in treatment course with no reimaging. To date, complete clinical response (cCR) has been observed in three patients (33%). All 10 patients are alive. Grade 3-4 treatment-related adverse events occurred in two patients (20%) who developed treatment-related strictures (one also had tumour perforation). This was successfully managed with defunctioning ileostomy and antibiotics, with subsequent cCR. Conclusions: We report impressive early outcomes of immunotherapy for locally advanced/metastatic MMRd CRC, with excellent downstaging and high predicted cCR. This highlights the importance of screening all CRC for MSI-H/MMRd. In the setting of initially unresectable CRC, an ICI-first approach can render patients eligible for surgery, however deep responses can result in local effects including strictures and/or perforation.

Chemoimmunotherapy plus radiotherapy in advanced esophageal squamous-cell carcinoma.

437 Background: Chemotherapy plus Immune checkpoint inhibitors (ICIs) have improved survival outcomes of patients with advanced or metastatic esophageal squamous-cell carcinoma in both first- and second-line settings. However, the benefit of additional radiotherapy for the residual esophageal lesion after chemo-immunotherapy remains unclear. Methods: We conducted a one-arm, three-center, open label study involving patients who were treatment naïve, radiological and histological confirmed advanced or metastatic squamous-cell esophageal carcinoma. Enrolled patients were expected the survival time was three months or longer; and ECOG performance status score was 0 or 1. In induction phase, patients received four cycles of TP regimen chemotherapy (docetaxel, 75/mg 2 , iv on day 1 and cisplatin, 75mg/m 2 , iv on day 1) combined with PD-1 inhibitor (sintilimab, 200mg intravenous infusion on day 1) every 21 days. Patients who finished four cycles of chemo-immunotherapy with stable disease (SD) or partial response (PR) were initiated 50Gy/25f irradiation for residual tumors. 3-4weeks after radiotherapy, maintenance sintilimab therapy was administered every 21 days for another 31 cycles or until disease progression or intolerable toxicity. Results: Total of 39 patients were enrolled in this study, 30 of them could be evaluated in efficiency and toxicities. All of them were male and were squamous-cell carcinoma in histology. 12/30 (40.0%) patients were in stage III, and 18/30 (60.0%) were in stage IV. 29/30 (96.7%) patients completed four cycles chemo-immunotherapy, the complete response (CR) rate was 6.7% (2/30), the partial response (PR) rate was 53.3% (16/30) and disease control rate (DCR) was 86.7% (26/30). The median depth of response (DpR) was 34.5% for chemoimmunotherapy and was 64.0% after radiotherapy. The progression-free survival (PFS) was 16.4 months and the overall survival (OS) was not reached. The most common grade 3 or worse adverse event was neutropenia and occurred in 3 (10.0%) patients. Conclusions: Four cycles sintilimab plus cisplatin and docetaxel followed by radiotherapy for residual tumors and maintained sintilimab had high response rate, prolonged PFS and tolerable toxicities as first line treatment in patients with advanced or metastatic esophageal squamous-cell carcinoma. Longer OS is promising and more patients enrolled in this study is needed in future. Clinical trial information: NCT06138028 . Clinicopathological features and patient factors. Factors No. of patients (n=30) (%) Gender Male 30 (100.0) Female 0 (0) Age (year) < 65 27 (43.3) ≥ 65 17 (56.7) PD-L1 (CPS) < 5 9 (30.0) ≥ 5 21 (70.0) Clinical Stage III 12 (40.0) IV 18 (60.0) Metastatic Pattern Regional lymph node 12 (40.0) Cervical & Supraclavicular 4 (13.3) Abdomen 5 (16.7) Lung 6 (20.0)

Dose measurements with the Pille-ISS thermoluminescent dosimeter system during extravehicular activities (2004-2022).

One of the most problematic goals for radiation safety during spaceflight is an assessment of additional doses received by astronauts during extravehicular activity (EVA). The Pille-ISS thermoluminescent dosimeter developed by the predecessor of the Hungarian Research Network (HUN-REN) Centre for Energy Research (Budapest, Hungary) is designed for the routine dose measurements not only inside the spacecraft compartments, but also for personal dosimetric control for EVA. During almost two decades of the International Space Station (ISS) operation, the unique set of 131 EVA doses were recorded in different conditions, such as: solar activity, ISS trajectory along the South Atlantic Anomaly (SAA), and shielding conditions provided by two kinds of spacesuits: the Extravehicular Mobility Unit (EMU) and Orlan. The EVA dose rates during the normal scenario (without SAA crossing during EVA) are: 26 μGy/h on average, with maximum value of 118 μGy/h for the EMU spacesuit; and 103 μGy/h on average, with maximum value of 255 μGy/h for the Orlan spacesuit. However, the corresponding EVA dose can increase by about 33% on average regardless the spacesuit type, depending on time spent in SAA. The worst case mean EVA dose is equivalent to ∼ 7 days inside the ISS with 2.423 mGy. In general, the possible additional radiation risk due to the EVA is small in comparison with typical half-year mission onboard the ISS. The long-term experience of EVA dose assessments with Pille-ISS dosimeter shows that in some cases the skin dose can be underestimated due to the excessive shielding of the standard Pille-ISS dosimeter. To solve this problem, the modified Pille-ISS dosimeters with significantly reduced shielding are developed and involved onboard the ISS for the dose measurements starting from 2023.

Radiation exposure in concurrent abdominoplevic and chest CT Scans: an analysis of overlap and clinical impact

This study investigated the additional radiation exposure, influencing factors, and clinical significance of overlappingZ-axis coverage in abdominopelvic CT scans performed consecutively after same-day chest CT scans. Data from 761 patients were analyzed, with measuring the total and overlappingZ-axis coverage of the portal venous phase in abdominopelvic CT scans. The average overlapping portion was 33.8 ± 12.1 mm, accounting for approximately 7.0% of the total scan length, contributing a dose-length product of 33.4 mGy*cm and an effective radiation dose of 0.5 mSv. Male sex and the total scan length were identified as significant factors influencing overlap (p= 0.002 and < 0.001, respectively). Despite overlapping scans frequently imaging the lower lungs, only 8.4% of abdominopelvic CT reports specifically mentioned lower lung abnormalities, indicating limited clinical utility. These findings underscore the importance of optimizing CT protocols to minimize the total length of the body covered in abdominopelvic scans, thereby reducing unnecessary radiation exposure during concurrent chest and abdominopelvic CT scans.

Constraints on Primordial Black Holes from Neff: Scalar-induced Gravitational Waves as an Extra Radiation Component

Abstract In 2023 June, multiple pulsar timing array collaborations provided evidence for the existence of a stochastic gravitational-wave background. Scalar-induced gravitational waves (SIGWs), as one of the most likely sources of stochastic gravitational waves, have received widespread attention. When primordial curvature perturbations on small scales are sufficiently large, primordial black holes (PBHs) inevitably form, concurrently producing SIGWs with significant observable effects. These SIGWs can serve as an additional radiation component, influencing the relativistic degrees of freedom N eff. Taking into account primordial non-Gaussianity, we study the energy density spectrum of SIGWs up to the third order and use the current observational data of N eff to constrain small-scale primordial curvature perturbations and the abundance of PBHs.

Efficacy of Neoadjuvant Radiotherapy After Chemotherapy and the Optimal Interval from Radiotherapy to Surgery for Borderline Resectable and Resectable Pancreatic Cancer.

Benefits of neoadjuvant treatment for pancreatic cancer with major vessel invasion has been demonstrated through randomized controlled trials; however, the optimal neoadjuvant treatment strategy remains controversial, especially for radiotherapy. Therefore, we aimed to evaluate the efficacy and safety of neoadjuvant radiotherapy followed by chemotherapy and the optimal time interval to undergo surgery after radiotherapy in (borderline) resectable pancreatic cancer. Between 2013 and 2022, patients with (borderline) resectable pancreatic cancer with vessel contact who received 5-fluorouracil with leucovorin, oxaliplatin, and irinotecan or gemcitabine and nanoparticle albumin-bound paclitaxel as initial treatment following surgery were included. Patients who received radiotherapy after chemotherapy and those who did not were matched using 1:1 nearest-neighbor propensity scores. Propensity scores were measured using the tumor size at initial image, duration of neoadjuvant chemotherapy, and responsiveness to neoadjuvant chemotherapy. Of 212 patients, 166 patients were retrieved for the matched cohort. Patients who received radiotherapy had significantly better postoperative survival, local control, and R0 resection rates than those who did not. Furthermore, patients who underwent surgery within 4 weeks after completing radiotherapy had lower intraoperative blood loss and a clinically relevant postoperative pancreatic fistula rate than those who underwent surgery after more than 4 weeks. In patients with (borderline) resectable pancreatic cancer with vessel contact who were scheduled for curative-intent surgery after neoadjuvant chemotherapy, additional radiotherapy was associated with better postoperative survival and local control. Furthermore, our findings suggested that scheduling surgery within 4 weeks following radiation therapy might enhance the perioperative outcomes.

Highlights on gastroesophageal tumors: the comeback of FLOT

Summary This article aims to summarize the highlights of the two largest global congresses of 2024 with respect to gastroesophageal tumors. The triplet chemotherapy combination known as FLOT (5-fluorouracil, leucovorin, oxaliplatin, docetaxel), used as perioperative chemotherapy, was demonstrated to improve overall and disease-free survival in resectable gastroesophageal cancer patients some time ago. Despite being standard for this patient population, many questions for different scenarios remain open: Is FLOT also efficacious in patients with esophageal or gastroesophageal junction adenocarcinoma when compared to neoadjuvant chemoradiotherapy? Is FLOT a feasible chemotherapy option for oligometastatic patients, thereby contributing to the overall survival as “neoadjuvant” treatment before palliative resection? Can the efficacy of FLOT be strengthened by applying additional radiation treatment to patients with gastroesophageal adenocarcinoma? Is FLOT really necessary in the adjuvant setting for all patients, or can the adjuvant treatment be guided based on pathological response rates? These questions were answered to some extent in the ESOPEC and RENAISSANCE trials at the American Society of Clinical Oncology (ASCO) meeting and the TOPGEAR and SPACE-FLOT trials at European Society for Medical Oncology (ESMO) meeting. Many other FLOT-related studies for resectable as well as metastatic gastroesophageal cancer patients are yet to come.

Measurement of lumbar vertebral body attenuation at PET-CT is a reliable method of diagnosing osteoporosis.

This study investigates the potential of positron emission tomography-computed tomography (PET-CT) as a reliable tool for the diagnosis of osteoporosis, using attenuation values as a marker for bone mineral density (BMD) assessment. We retrospectively identified 305 patients who underwent both PET-CT and dual-energy X-ray absorptiometry (DEXA) within a six-month interval at a tertiary healthcare centre. Attenuation values were measured from the first lumbar vertebra (L1) on noncontrast CT images acquired during PET-CT scans. These values were then compared with corresponding DEXA T-scores to determine their diagnostic performance. Statistical analyses, including one-way Analysis of Variance (ANOVA), Pearson correlation, and receiver operating characteristic (ROC) curve analysiswere employed to assess the correlation between PET-CT attenuation values and DEXA-defined osteoporosis. The mean Hounsfield units (HU) differed significantly between groups classified by DEXA as osteoporosis, osteopenia, or normal BMD (P < 0.001). A strong correlation was found between HU and DEXA T-scores (Pearson coefficient=0.65). Using logistic regression, we identified HU thresholds of 120 for 90% sensitivity and 98 for 90% specificity. The optimal balanced threshold was 109 HU, achieving both 80% sensitivity and specificity. The ROC curve for the model showed an area under the curve (AUC) of 0.88, indicating high diagnostic accuracy. PET-CT can effectively screen for osteoporosis, offering a noninvasive, opportunistic diagnostic tool that requires no additional radiation exposure or resources. This study establishes 109 HU as the optimal threshold for diagnosing osteoporosis on PET-CT, providing a significant opportunity for early intervention and improved patient care.

Radiation Therapy Improves Survival in Patients with Distant Metastatic Head and Neck Squamous Cell Carcinoma: A Retrospective Study.

The role of radiation therapy in patients with distant metastatic squamous cell carcinoma of the head and neck (mHNSCC) is unclear. In this study, we compare the differences in survival among mHNSCC patients treated with chemotherapy plus radiotherapy (RT) vs. chemotherapy alone. This study included patients with distant mHNSCC recruited from 2 cohorts: The Surveillance, Epidemiology, and End Results (SEER [N=885]) database and a Chinese single-institution registry in Sun Yat-sen University Cancer Center (SYSUCC [N=60]). The SEER cohort included 600 patients received RT plus chemotherapy and 285 patients received chemotherapy alone; in the SYSUCC cohort, 40 patients received RT plus chemotherapy and 20 patients received chemotherapy alone were recruited. The period of data collection for the SEER study was from January 2010 to December 2015, and that for SYSUCC was from January 2010 to December 2020. The study's primary outcome was overall survival (OS), with disease-specific survival (DSS) as a secondary outcome. Of the 885 patients in the SEER cohort, the addition of RT to chemotherapy increased one-year OS from 46.6% to 56.0% compared with chemotherapy alone (P =0.009) and from 10.4% to 25.1% for three-year OS (P <0.001). Patients who received RT in addition to chemotherapy were also more likely to have better three-year DSS than those who received chemotherapy alone (28.9% vs. 14.0%, P<0.001). Similarly, in the SYSUCC cohort, patients who received chemotherapy plus RT had better three-year OS than chemotherapy alone (62.8% vs. 21.0%, P=0.003). The addition of RT to chemotherapy increased median OS among patients with mHNSCC from 10 months to 13 months in the SEER cohort and from 14 months to 29 months in the SYSUCC cohort. Radiotherapy in addition to chemotherapy significantly improved OS and DSS in patients with mHNSCC.

The rotation method for correcting renal depth in the determination of glomerular filtration rate using Tc-99m diethylenetriamine pentaacetic acid (DTPA)-based renal dynamic imaging in patients with hydronephrosis.

Kidney depth significantly affects the accuracy of glomerular filtration rate (GFR) measurement, and hydronephrosis-induced morphological changes further challenge its estimation through traditional formulas. This study evaluated the rotation method's efficacy in correcting kidney depth and depth difference during Tc-99m diethylenetriamine pentaacetic acid (DTPA) renal dynamic imaging for GFR assessment. This study analyzed 66 individuals treated at First Hospital of Shanxi Medical University with unilateral hydronephrosis between January 2022 and June 2023. Abdominal computed tomography (CT) scans were used to classify hydronephrosis severity into mild (20 cases), moderate (23 cases), and severe hydronephrosis groups (23 cases). Depth and depth differences of the kidneys were measured using CT, the rotation method, the Tonnesen formula, and the Li-Qian formula to evaluate their impact on total and single-kidney GFR. (I) Regarding renal depth and GFR, compared to CT, the Tonnesen formula underestimated both the depth and GFR for normal and hydronephrotic kidneys (NKs and HKs). The mean depth of normal kidneys (NKs) measured by the Tonnesen formula was 6.14 cm, approximately 19% lower than the 7.59 cm measured by CT. Similarly, the GFR of NKs estimated by the Tonnesen formula was 37.13 mL/min/1.73 m2, approximately 21% lower than the 47.24 mL/min/1.73 m2 measured by CT (P<0.05). The Li-Qian formula underestimated the renal depth and GFR for HKs. The mean depth of HKs measured by the Li-Qian formula was 7.62 cm, approximately 9% lower than the 8.41 cm measured by CT. Similarly, the GFR estimated by the Li-Qian formula was 25.50 mL/min/1.73 m2, about 19% lower than the 31.51 mL/min/1.73 m2 measured by CT (P<0.05). There were no statistically significant differences in the GFR or renal depth measurements between the rotation method and CT for both NKs and HKs (P>0.05). In HKs, the depth and GFR measured by the rotation method were 8.17 cm and 30.41 mL/min/1.73 m2, respectively, closely matching the CT measurements of 8.41 cm and 31.51 mL/min/1.73 m2. (II) A comparison of the renal depth and GFR in the mild, moderate, and severe hydronephrosis groups was conducted. Compared with CT, the Tonnesen formula undervalued renal depth and GFR across all severity levels (P<0.05); meanwhile, the Li-Qian formula underestimated the renal depth and GFR of the moderate and severe hydronephrosis groups (P<0.05). The rotation method demonstrated no variance across the three groups compared to CT (P>0.05). (III) In terms of depth difference, the Tonnesen and the Li-Qian formulae produced a significantly lower value than did CT (P<0.05). Statistical analyses showed no difference between the rotation and CT methods (P>0.05). In patients with hydronephrosis, the renal depth and depth difference measured by the rotation method are similar to those measured by CT, which can accurately correct the renal depth and depth difference without increasing the patient's additional radiation, enhancing the precision of total and separate renal GFR.

Detection of alteration in carotid artery volumetry using standard-of-care computed tomography surveillance scans following unilateral radiation therapy for early-stage tonsillar squamous cell carcinoma survivors: a cross-sectional internally-matched carotid isodose analysis.

This study leveraged standard-of-care CT scans of patients receiving unilateral radiotherapy (RT) for early tonsillar cancer to detect volumetric changes in the carotid arteries, and determine whether there is a dose-response relationship. Disease-free cancer survivors (>3 months since therapy and age>18years) treated with intensity modulated RT for early (T1-2, N0-2b) tonsillar cancer with pre- and post-therapy contrast-enhanced CT scans available were included. Patients treated with definitive surgery, bilateral RT, or additional RT before the post-RT CT scan were excluded. Isodose lines from treatment plans were projected onto both scans, facilitating the delineation of carotid artery subvolumes in 5Gy increments (i.e. received 50-55Gy, 55-60Gy, etc.). The percent-change in sub-volumes across each dose range was examined. Among 46 patients, 72% received RT alone, 24% induction chemotherapy followed by RT, and 4% concurrent chemoradiation. The median interval from RT completion to the latest, post-RT CT scan was 43months (IQR 32-57). A decrease in the volume of the irradiated carotid artery was observed in 78% of patients, while there was a statistically significant difference in mean %-change (±SD) between the total irradiated and spared carotid volumes (-7.0±9.0 vs.+3.5±7.2, respectively, p<0.0001). Chemotherapy use, in addition to RT, was associated with a significant mean %-decrease in carotid artery volume compared to RT alone. No significant dose-response trend was observed in the carotid artery volume change within 5Gy ranges. Our data show that standard-of-care oncologic surveillance CT scans can effectively detect reductions in carotid volume following RT for oropharyngeal cancer. Changes were equivalent between studied dose ranges, denoting no further dose-response effect beyond 50Gy.

Development of a low-dose strategy for propagation-based imaging helical computed tomography (PBI-HCT): high image quality and reduced radiation dose

Background. Propagation-based imaging computed tomography (PBI-CT) has been recently emerging for visualizing low-density materials due to its excellent image contrast and high resolution. Based on this, PBI-CT with a helical acquisition mode (PBI-HCT) offers superior imaging quality (e.g., fewer ring artifacts) and dose uniformity, making it ideal for biomedical imaging applications. However, the excessive radiation dose associated with high-resolution PBI-HCT may potentially harm objects or hosts being imaged, especially in live animal imaging, raising a great need to reduce radiation dose.Methods. In this study, we strategically integrated Sparse2Noise (a deep learning approach) with PBI-HCT imaging to reduce radiation dose without compromising image quality. Sparse2Noise uses paired low-dose noisy images with different photon fluxes and projection numbers for high-quality reconstruction via a convolutional neural network (CNN). Then, we examined the imaging quality and radiation dose of PBI-HCT imaging using Sparse2Noise, as compared to when Sparse2Noise was used in low-dose PBI-CT imaging (circular scanning mode). Furthermore, we conducted a comparison study on the use of Sparse2Noise versus two other state-of-the-art low-dose imaging algorithms (i.e., Noise2Noise and Noise2Inverse) for imaging low-density materials using PBI-HCT at equivalent dose levels.Results. Sparse2Noise allowed for a 90% dose reduction in PBI-HCT imaging while maintaining high image quality. As compared to PBI-CT imaging, the use of Sparse2Noise in PBI-HCT imaging shows more effective by reducing additional radiation dose (30%-36%). Furthermore, helical scanning mode also enhances the performance of existing low-dose algorithms (Noise2Noise and Noise2Inverse); nevertheless, Sparse2Noise shows significantly higher signal-to-noise ratio (SNR) value compared to Noise2Noise and Noise2Inverse at the same radiation dose level.Conclusions and significance. Our proposed low-dose imaging strategy Sparse2Noise can be effectively applied to PBI-HCT imaging technique and requires lower dose for acceptable quality imaging. This would represent a significant advance imaging for low-density materials imaging and for future live animals imaging applications.

Effect of Supplemental UV-B Radiation and Water Limitation on Plant Growth, Yield and Berry Composition of the Greek Grapevine Cultivar “Romeiko” Under Mediterranean Field Conditions

This work aims to evaluate the performance of the grapevine (Vitis vinifera L.) cultivar Romeiko under the influence of limited water availability and additional UV-B radiation exposure, applied alone or in combination. Three-year-old grapevines were exposed to two water regimes (well watered and water stressed) and two levels of UV-B radiation (ambient UV-B and ambient plus 15% UV-B). Predawn leaf water potential (&amp;Psi;PD) and leaf relative water content (RWC) were significantly higher in well watered plants and on the other hand, no significant effect of UV-B on leaf tissue hydration was revealed. Both abiotic stressors significantly affected shoot growth rate (SGR), leaf fresh weight (FW) and leaf dry eight (DW), with the effect of water shortage on vegetative growth being more pronounced. Deficit irrigation had negative effects on yield both because of the reduced berry fresh weight and the lesser number of berries per cluster, while the yield response (quantity and quality attributes) of cv. Romeiko was similar between the two UV-B radiation regimes. In summary, limited water supply had a high potential for restricting vegetative growth and yield, whereas the effects of enhanced UV-B radiation were less evident on allometric parameters and nonexistent on fruit yield and quality characteristics. In addition, the combination of supplemental UV-B and deficit irrigation did not cause any pronounced effects compared to the single application of limited water supply.

Onsite ammonia synthesis from water vapor and nitrogen in the air.

An innovative method for onsite ammonia synthesis under ambient conditions has been developed using a catalyst mesh composed of magnetite (Fe3O4) and Nafion polymer. We pass air through the catalyst, which condenses microdroplets from atmospheric water vapor and uses nitrogen from the air, resulting in ammonia concentrations ranging from 25 to 120 μM in 1 hour, depending on local relative humidity. Operated at room temperature and atmospheric pressure, this technique eliminates the need for additional electricity or radiation, thereby substantially reducing carbon dioxide emissions compared to the traditional Haber-Bosch process. In laboratory experiments, we further optimized the reaction conditions and scaled up the process. After 2 hours of spraying, the ammonia concentration increased to 270.2 ± 25.1 μM. In addition, we present a portable device designed for onsite ammonia production which consistently produces an ammonia concentration that is adequate for some agricultural irrigation purposes.

Comparison between non-contrast-enhanced MRA and contrast-enhanced CTA in the assessment of hepatic arterial vasculature of donors before liver transplantation

BackgroundRadiologic evaluation is crucial in minimizing transplant complications and guaranteeing the donor’s safety, as a variety of anatomical variations characterizes hepatic vascularity. Computed tomographic angiography (CTA) is the gold standard in hepatic vascularity evaluation in donors before liver transplantation. Still, the procedure necessitates intravenous contrast medium injection, which entails nephrotoxicity risk and hypersensitivity reactions. These concerns about contrast medium safety encouraged new developments in non-contrast-enhanced magnetic resonance angiography (NC-MRA) techniques for imaging the vascular anatomy of the liver.ResultsThis study was conducted on 40 patients of potential liver donors. Thirty-six cases (90%) showed excellent image quality by CTA versus 14 cases (35%) by NC-MRA; on the other hand, 21 cases (52.5%) showed good image quality by NC-MRA while versus 2 cases (5%) by CTA and NC-MRA documented 5 cases (12.5%) with fair image quality versus two cases documented by CTA. Both modalities provided diagnostic image quality in all cases. Michel’s classification was employed to identify four distinct kinds of hepatic artery anatomy using CTA. Thirty-nine cases out of 40 were successfully identified using NC-MRA. Segment IV hepatic artery origin could not be identified in 6 cases using NC-MRA versus one case using CTA. Artifacts were noted in 20 cases (50%) using NC-MRA versus 2 cases (5%) using CTA.ConclusionCTA is the gold standard for pre-liver transplant donor evaluation. The emerging technology of non-contrast MRA has an added value with fewer patient complications. It may function as an additional donor examination when CTA is unable to provide adequate diagnostic information. Non-contrast MRA yields reliable results and eliminates the necessity for contrast medium and additional radiation exposure.

Use of surface tracking recordings to identify pitfalls during surface-guided radiotherapy.

The precise daily positioning of patients during radiation therapy determines the quality of the entire treatment. To avoid additional radiation exposure from regular cone-beam CT (CBCT) scans, surface-guided radiotherapy systems (SGRT) are increasingly used. The aim of this prospective clinical study was to evaluate the advantages, feasibility, and pitfalls of SGRT using the surface tracking recorder prototype of the camera component of ExacTrac Dynamic (Brainlab AG, Munich, Germany). This system combines both surface-based imaging technology and athermographic camera that records patients via thermal imaging to accurately measure patient geometry. The surfaces of patients with various tumor entities and therefore different regions of interest (ROIs) were recorded with the surface camera during positioning and throughout treatment. Subsequently, these surface camera datasets were analyzed to compare the accuracy of patient positioning with the current treatment standard (X-ray-based IGRT). The camera components were used only as an imaging tool and not to correct any deviations. For evaluation of typical pitfalls, errors > 5 mm for extracranial indications and > 2 mm for cranial indications were analyzed using parameters extracted from the surface recordings and the corresponding CBCT shifts. In total, 162 displacement vector datasets for 130 patients were generated and evaluated. The smallest deviations were found in the head and neck regions (mean deviation 1.9 mm/0.8°). The largest mean translational deviation (4.8 mm) and mean rotational deviation (1.1°) were found in the pelvic area. In all regions, most datasets showed clinically acceptable deviations; however, large outliers were observed in some measurements, particularly longitudinally. These outliers are of special interest because they may indicate mistakes in the use of SGRT, and they were therefore analyzed separately in detail. Several reasons for the outliers were identified, and potential solutions to avoid these pitfalls are presented. This observational study demonstrated the advantages and pitfalls of SGRT by using the surface tracking recorder prototype of the camera component of ExacTrac Dynamic. These pitfalls can be avoided through thorough application of SGRT. This study may serve as apractical guide for clinicians already using or introducing SGRT for patient positioning.