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Purpose: Hippocampal-avoidance whole-brain radiotherapy (HA-WBRT) planning can present challenges. This study examines the influence of head tilt angles on the dosimetric characteristics of target and organs at risk (OARs), aiming to identify the optimal tilt angle that yields optimal dosimetric outcomes using tomotherapy (TOMO). Methods: Eight patients diagnosed with brain metastases underwent CT scans at five tilt angles: [0°, 10°), [10°, 20°), [20°, 30°), [30°, 40°), and [40°, 45°]. Treatment plans were generated using TOMO and volumetric modulated arc therapy (VMAT). Dosimetric parameters including conformity index (CI), homogeneity index (HI), D2cc, D98%, and Dmean of PTV, as well as Dmax, and Dmean of OARs were analyzed. Furthermore, a comparison was made between the dosimetric parameters of TOMO and VMAT plans. Finally, delivery efficiency of TOMO plans were assessed. Results: For the PTV, [40°, 45°] tilt angle demonstrated significantly better conformity, homogeneity, lower D2cc, and lower Dmean for the PTV. Regarding the OARs, the [40°, 45°] head tilt angle demonstrated significantly lower Dmax and Dmean in hippocampus, eyes, optic chiasm, and optic nerves. The [40°, 45°] tilt angle also showed significantly lower Dmax for brainstem and cochleas, as well as a lower Dmean for lens. In the [40°,45°] tilt angle for HA-WBRT, TOMO showed superior performance over VMAT for the PTV. TOMO achieved lower Dmax for brainstem, cochleas, optic nerves, and optic chiasm, as well as a lower Dmean for hippocampus. Furthermore, a significant correlation was found between delivery time and the PTV projection length in the sagittal plane. Conclusion: The TOMO plan utilizing a tilt angle range of [40°, 45°] demonstrated superior PTV conformity and uniformity, along with enhanced OARs sparing. Furthermore, it exhibited a dosimetric advantage over VMAT for PTV and most OARs at the same angle range. [ABSTRACT FROM AUTHOR]

Background: Circular RNAs (circRNAs) are implicated in retinal pathophysiology; however, their expression profiles and functions in photoreceptor apoptosis are largely unknown. We explored circRNA‐expression profiles and circUvrag (host gene: Uvrag, ultraviolet radiation resistance associated gene) function in light‐induced photoreceptor apoptosis. Methods: Sprague–Dawley rats and 661 W photoreceptor cells were exposed to blue light to establish light‐induced photoreceptor degeneration. Differentially expressed circRNAs were identified using microarrays. Potential functions of dysregulated circRNAs were analysed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. CircUvrag expression and localization were evaluated using quantitative RT‐PCR and fluorescence in situ hybridization, respectively. CircUvrag overexpression and knockdown were induced using a plasmid and a small interfering RNA, respectively, and retinal function and structure were assessed using scotopic electroretinography, haematoxylin–eosin staining, and TUNEL staining. Microglial migration was assessed using IBA1 immunostaining. The apoptosis ratio of photoreceptor cells in vitro was detected using flow cytometry. Results: We identified 764 differentially expressed circRNAs, which were potentially related with the development of retinal structures, including neurons, dendrites, and synapses, and might participate in nervous‐system pathophysiology. Light exposure enriched circUvrag in the cytoplasm of photoreceptors in the outer nuclear layer (ONL). CircUvrag knockdown decreased photoreceptor apoptosis and microglial migration to the ONL after light exposure, preserving ONL thickness and a‐wave amplitude. In vitro, circUvrag knockdown inhibited photoreceptor apoptosis, although circUvrag overexpression slightly promoted photoreceptor apoptosis. Conclusions: CircUvrag knockdown attenuated light‐induced photoreceptor apoptosis, and might be a potential target in retinal degeneration. [ABSTRACT FROM AUTHOR]

Introduction: This retrospective study investigated the clinical characteristics of multiple subretinal fluid blebs (MSFBs) after successful surgery for rhegmatogenous retinal detachment (RRD) and explored the association between MSFB with best-corrected visual acuity (BCVA) and metamorphopsia. Methods: The study comprised 206 patients after successful surgery for RRD, with 58 and 148 eyes undergoing, respectively, scleral buckling (SB), and pars plana vitrectomy (PPV). The clinical characteristics of MSFBs were analyzed by optical coherence tomography (OCT). The choroidal vessels in some cases were evaluated with OCT angiography. M-charts were used to determine the metamorphopsia. Results: MSFBs occurred in 17 (29.3%) and 8 (5.4%) eyes given SB and PPV, respectively. MSFBs appeared 5.6 ± 5.5 weeks after surgery and required 34.9 ± 13.8 weeks to disappear. Disrupted external limiting membrane and ellipsoid zone could still be seen in 83.3% and 66.7% of the patients 12 months after surgery; these rates were significantly higher than those of patients without MSFBs (p = 0.047, 0.022, respectively). Twelve months post-surgery, BCVA and metamorphopsia scores of the patients with MSFBs were statistically comparable to those of the controls. Conclusions: MSFBs occur more commonly after SB than PPV. MSFBs may delay the recovery of the outer retina structure but do not affect postoperative BCVA and metamorphopsia. [ABSTRACT FROM AUTHOR]