Excitation of the Ganymede Ultraviolet Aurora

We analyze the ultraviolet aurorae observed on Ganymede by means of the Hubble Space Telescope and compare them to similar phenomena on Earth. We find that the tenuous nature of Ganymede's atmosphere precludes excitation of the aurora by high-energy electrons and requires a local acceleration mechanism. We propose the following as plausible mechanisms for generating both the continuous background emission and the intense auroral bright spots

Experimental Evidence for Defect Tolerance in Pb-Halide Perovskites

The term defect tolerance (DT) is used often to rationalize the exceptional optoelectronic properties of Halide Perovskites, HaPs, and their devices. Even though DT lacked direct experimental evidence, it became fact in the field. DT in semiconductors implies tolerance to structural defects without the electrical and optical effects (e.g., traps), associated with such defects. We present first direct experimental evidence for DT in Pb HaPs by comparing the structural quality of 2D, 2D_3D, and 3D Pb HaP crystals with their optoelectronic characteristics using high sensitivity methods. Importantly, we get information from the material bulk, because we sample at least a few 100 nm, up to several micrometer, from the sample surface, which allows assessing intrinsic bulk (and not only surface) properties of HaPs. The results point to DT in 3D, to a lesser extent in 2D_3D, but not in 2D Pb HaPs. We ascribe such dimension dependent DT to the higher number of (near)neighboring species, available to compensate for structural defect effects in the 3D than in the 2D HaP crystals. Overall, our data provide an experimental basis to rationalize DT in Pb HaPs. These experiments and findings can guide the search for, and design of other materials with DT

Volumetric and Voxel-Wise Analysis of Dominant Intraprostatic Lesions on Multiparametric MRI

Introduction: Multiparametric MR imaging (mpMRI) has shown promising results in the diagnosis and localization of prostate cancer. Furthermore, mpMRI may play an important role in identifying the dominant intraprostatic lesion (DIL) for radiotherapy boost. We sought to investigate the level of correlation between dominant tumor foci contoured on various mpMRI sequences. Methods: mpMRI data from 90 patients with MR-guided biopsy-proven prostate cancer were obtained from the SPIE-AAPM-NCI Prostate MR Classification Challenge. Each case consisted of T2-weighted (T2W), apparent diffusion coefficient (ADC), and K(trans) images computed from dynamic contrast-enhanced sequences. All image sets were rigidly co-registered, and the dominant tumor foci were identified and contoured for each MRI sequence. Hausdorff distance (HD), mean distance to agreement (MDA), and Dice and Jaccard coefficients were calculated between the contours for each pair of MRI sequences (i.e., T2 vs. ADC, T2 vs. K(trans), and ADC vs. K(trans)). The voxel wise spearman correlation was also obtained between these image pairs. Results: The DILs were located in the anterior fibromuscular stroma, central zone, peripheral zone, and transition zone in 35.2, 5.6, 32.4, and 25.4% of patients, respectively. Gleason grade groups 1-5 represented 29.6, 40.8, 15.5, and 14.1% of the study population, respectively (with group grades 4 and 5 analyzed together). The mean contour volumes for the T2W images, and the ADC and K(trans) maps were 2.14 +/- 2.1, 2.22 +/- 2.2, and 1.84 +/- 1.5 mL, respectively. K(trans) values were indistinguishable between cancerous regions and the rest of prostatic regions for 19 patients. The Dice coefficient and Jaccard index were 0.74 +/- 0.13, 0.60 +/- 0.15 for T2W-ADC and 0.61 +/- 0.16, 0.46 +/- 0.16 for T2W-K(trans). The voxel-based Spearman correlations were 0.20 +/- 0.20 for T2W-ADC and 0.13 +/- 0.25 for T2W-K(trans). Conclusions: The DIL contoured on T2W images had a high level of agreement with those contoured on ADC maps, but there was little to no quantitative correlation of these results with tumor location and Gleason grade group. Technical hurdles are yet to be solved for precision radiotherapy to target the DILs based on physiological imaging. A Boolean sum volume (BSV) incorporating all available MR sequences may be reasonable in delineating the DIL boost volume

A Deep Dive into Understanding Tumor Foci Classification using Multiparametric MRI Based on Convolutional Neural Network

Deep learning models have had a great success in disease classifications using large data pools of skin cancer images or lung X-rays. However, data scarcity has been the roadblock of applying deep learning models directly on prostate multiparametric MRI (mpMRI). Although model interpretation has been heavily studied for natural images for the past few years, there has been a lack of interpretation of deep learning models trained on medical images. This work designs a customized workflow for the small and imbalanced data set of prostate mpMRI where features were extracted from a deep learning model and then analyzed by a traditional machine learning classifier. In addition, this work contributes to revealing how deep learning models interpret mpMRI for prostate cancer patients stratification

(P44) Is Prophylactic Cranial Irradiation Necessary in Stage I-IIA Small Cell Lung Cancer Patients? A Single Institution Experience

Background: The advent of screening chest computed tomography (CT) for high-risk patients has increased the patient population presenting with early-stage small cell lung cancer (SCLC). While surgical resection continues to be standard of care, stereotactic body radiation therapy (SBRT) is an option for non-surgical candidates. Although the effectiveness of PCI in patients with limited stage SCLC has been well established, decreasing the brain metastasis incidence from approximately 70% to 30%, the role of PCI in early-stage SCLC (T1-T2) has not been fully elucidated. This study reports our experience omitting PCI in early-stage SCLC. Objectives: This study reports our experience omitting PCI in early stage SCLC. Methods: Fourteen patients with early-stage SCLC, nine patients with clinical stage I (T1) and five patients with stage IA (T2) SCLC, ranging in age from 54-81 years old, treated with surgical resection or SBRT from July 2015 to May 2021 at our institution, were retrospectively reviewed. Positron emission tomography (PET) was used in the staging of 93% of patients. All patients had initial negative brain MRI and opted not to receive PCI. 71% of the patients had brain scan surveillance for follow-up. Risk factors including age, gender, and tumor size, were analyzed for overall survival (OS), loco-regional recurrence (LRR), and distant metastasis (DM) using the Log-rank test. Results: With a median follow-up of 13 months (range 2-63), none of our patients developed metastases to the brain. Adjuvant chemotherapy, with a mean of 4 cycles (2-6) was administered to 13 out of 14 patients (92%). The 2-year OS, LRR and DM estimates were 47% [95% CI (0.14, 0.75)], 57% [95% CI (0.19, 0.82)], and 51% [95% CI (0.17, 0.77)], respectively. The OS and the frequency of LRR were not found to be correlated with age, gender, or tumor size. DM was significantly higher in males vs females (P=0.016). Conclusions: Our experience in patients with Stage I-IIA SCLC treated with surgery or SBRT did not demonstrate any development of brain metastases. As PCI carries long term risks of neurotoxicity, close surveillance with regular brain imaging may be a reasonable alternative. Adjuvant systemic therapy remains an important component of treatment

Detectors for the Gamma-Ray Resonant Absorption (GRA) Method of Explosives Detection in Cargo: A Comparative Study

Gamma-Ray Resonant Absorption (GRA) is an automatic-decision radiographic screening technique that combines high radiation penetration with very good sensitivity and specificity to nitrogenous explosives. The method is particularly well-suited to inspection of large, massive objects (since the incident gamma-ray probe is at 9.17 MeV) such as aviation and marine containers, heavy vehicles and railroad cars. Two kinds of gamma-ray detectors have been employed to date in GRA systems: 1) Resonant-response nitrogen-rich liquid scintillators and 2) BGO detectors. This paper analyses and compares the response of these detector-types to the resonant radiation, in terms of single-pixel figures of merit. The latter are sensitive not only to detector response, but also to accelerator-beam quality, via the properties of the nuclear reaction that produces the resonant gamma-rays. Generally, resonant detectors give rise to much higher nitrogen-contrast sensitivity in the radiographic image than their non-resonant detector counterparts and furthermore, do not require proton beams of high energy-resolution. By comparison, the non-resonant detectors have higher gamma-detection efficiency, but their contrast sensitivity is very sensitive to the quality of the accelerator beam. Implications of these detector/accelerator characteristics for eventual GRA field systems are discussed.Comment: 11 page

The Influence of Dosimetric Parameters on Quality of Life for Early Stage Non-small Cell Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy

Background: Lung stereotactic body radiotherapy (SBRT) has become a standard treatment option for early stage non-small cell lung cancer (NSCLC) patients who are medically inoperable. The influence of radiation dose/volume parameters on quality of life is not known. Our hypothesis is that clinically meaningful declines in quality of life over time will be associated with increased radiation lung dose/volume parameters. Objectives: To investigate clinical toxicity and quality of life (QOL) outcomes of stage I NSCLC patients after SBRT as a function of radiation dose/volume parameters. Methods: In this IRB-approved study, 55 stage I NSCLC patients who received SBRT (12 Gy x 4) and completed QOL forms were analyzed. Clinical symptoms and QOL were measured at baseline and at 3, 6, 12, 18, 24, and 36 months post-SBRT. Clinical toxicity was graded using the common terminology criteria for adverse effects (CTCAE v4.0). Quality of life was followed using the validated Functional Assessment of Cancer Therapy-Trial Outcome Index (FACT-TOI) instrument. Dosimetric parameters, including the mean lung radiation dose (MLD), and the volume of normal lung receiving \u3e 5, 10, 13 or 20 Gy (V5, V10, V13, and V20) were measured from the radiation treatment plan. Student\u27s t-test and Pearson correlation analyses were used to examine the relationships between radiation lung metrics and clinically meaningful changes in QOL and/or clinical toxicities. Kaplan-Meier method was used to estimate rates of local control (LC), disease free survival (DFS), and overall survival (OS). Results: With a median follow-up of 24 months, the 3 year LC, DFS, and OS were 93%, 65% and 84%, respectively, with 5.5% grade 3 toxicity and no grade 4 or 5 toxicities. Clinically meaningful declines in patient reported QOL (FACT-TOI, lung cancer subscale, physical well-being, and/or functional well-being) post-treatment significantly correlated with increased dosimetric parameters, such as V10, V13, and V20. Conclusions: While lung SBRT is associated with excellent LC and minimal clinical toxicity for early stage NSCLC, clinically meaningful declines in QOL significantly correlated with increasing lung dose/volume parameters. This suggests that further improvements in the techniques of lung SBRT have the potential to further enhance patients\u27 QOL following this treatment

The Influence of Dosimetric Parameters on Quality of Life for Early Stage Non-small Cell Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy

Background: Lung stereotactic body radiotherapy (SBRT) has become a standard treatment option for early stage non-small cell lung cancer (NSCLC) patients who are medically inoperable. The influence of radiation dose/volume parameters on quality of life is not known. Our hypothesis is that clinically meaningful declines in quality of life over time will be associated with increased radiation lung dose/volume parameters. Objectives: To investigate clinical toxicity and quality of life (QOL) outcomes of stage I NSCLC patients after SBRT as a function of radiation dose/volume parameters. Methods: In this IRB-approved study, 55 stage I NSCLC patients who received SBRT (12 Gy x 4) and completed QOL forms were analyzed. Clinical symptoms and QOL were measured at baseline and at 3, 6, 12, 18, 24, and 36 months post-SBRT. Clinical toxicity was graded using the common terminology criteria for adverse effects (CTCAE v4.0). Quality of life was followed using the validated Functional Assessment of Cancer Therapy-Trial Outcome Index (FACT-TOI) instrument. Dosimetric parameters, including the mean lung radiation dose (MLD), and the volume of normal lung receiving \u3e 5, 10, 13 or 20 Gy (V5, V10, V13, and V20) were measured from the radiation treatment plan. Student\u27s t-test and Pearson correlation analyses were used to examine the relationships between radiation lung metrics and clinically meaningful changes in QOL and/or clinical toxicities. Kaplan-Meier method was used to estimate rates of local control (LC), disease free survival (DFS), and overall survival (OS). Results: With a median follow-up of 24 months, the 3 year LC, DFS, and OS were 93%, 65% and 84%, respectively, with 5.5% grade 3 toxicity and no grade 4 or 5 toxicities. Clinically meaningful declines in patient reported QOL (FACT-TOI, lung cancer subscale, physical well-being, and/or functional well-being) post-treatment significantly correlated with increased dosimetric parameters, such as V10, V13, and V20. Conclusions: While lung SBRT is associated with excellent LC and minimal clinical toxicity for early stage NSCLC, clinically meaningful declines in QOL significantly correlated with increasing lung dose/volume parameters. This suggests that further improvements in the techniques of lung SBRT have the potential to further enhance patients\u27 QOL following this treatment