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Purpose/Aim: In this work, we examined the possible effects of ionizing radiation (IR) on biomechanical properties of the membrane-cytoskeleton of human erythrocytes, after X-ray irradiation. Materials and Methods: Whole human blood from three healthy middle-aged volunteers was drawn by venipuncture and stored in tubes containing anticoagulant. Six blood samples were collected for each volunteer. Five of them were irradiated in the range of 0.1 Gy-2.0 Gy doses and one was used as control. The morphology and the elastic modulus of the erythrocytes were examined using atomic force microscopy and just few drops of whole blood. Results: No morphological changes appeared according to the shape and the morphology of the erythrocytes. The elastic modulus of the irradiated samples was reduced with the increase of radiation dose. The findings indicate that X-ray irradiation affects the biomechanical properties of erythrocyte cytoskeleton. The mean value of Young's modulus of all the irradiated blood samples was significant difference from the control at a level,P < 0.01. Conclusions: The elastic modulus of the erythrocytes could be an indicator of the adverse effect in the human blood generated by IR exposure through a radiotherapy treatment.

Background Volumetric modulated arc therapy (VMAT) requires an accurate patient‐specific quality assurance (PSQA) program. In clinical practice, this is usually performed using the γ‐index and the two‐dimensional gamma passing rate (2D %GP). A three‐dimensional (3D) index incorporating the patient anatomy could be more useful for the 3D dose distribution verification. Purpose The current study demonstrates a thorough investigation of VMAT PSQA treatment plans by examining the correlation between 3D Gamma passing rate (%GP) and 2D %GP. The aim was to establish the tolerance limits (TL) and action limits (AL) that could be adopted in clinical practice. Materials and methods PSQA was performed for 67 head and neck (H&N) and 69 prostate treatment plans, using an appropriate phantom and the γ‐index method. The 3%/2  mm acceptance criterion was used. Treatment plans’ 2D% GP and 3D %GP values were collected and correlated with individual 3D %GP values of planning target volume (PTV) and organs at risk (OARs). Institutional TL and AL of both 2D %GP and 3D %GP were established using 30 prostate and 30 H&N treatment plans, as per recommendations proposed by AAPM TG‐218. Results A moderate correlation was observed between 2D %GP and 3D %GP of the treatment plans. Τhe correlations demonstrated a stronger association for the 3D %GP than for the 2D %GP with respect to the 3D %GP of the individual structures considered. The TL for the 3D %GP (both plan and individual) and the plans’ 2D %GP were generally more stringent, while the AL showed a wider range compared to the corresponding limits suggested by the TG‐218 protocol for plan 2D %GP. Conclusions Institution‐specific 3D %GP as well as TL and AL for treatment plan, PTV and OARs could be incorporated in the PSQA procedure in synergy with the 2D evaluation, as they can provide a more‐in‐depth‐view of the treatment quality.

Purpose This study aimed to assess the accuracy and dosimetric impact of the Acuros XB (AXB) algorithm compared to the Anisotropic Analytical Algorithm (AAA) in two situations. First, simple phantom geometries were set and analyzed; moreover, volumetric modulated arc therapy (VMAT) clinical plans for Head & Neck and lung cases were calculated and compared. Methods First, a phantom study was performed to compare the algorithms with radiochromic EBT3 film doses using one PMMA slab phantom and two others containing foam or air gap. Subsequently, a clinical study was conducted, including 20 Head & Neck and 15 lung cases irradiated with the VMAT technique. The treatment plans calculated by AXB and AAA were evaluated in terms of planning target volume (PTV) coverage (V95%), dose received by relevant organs at risk (OARs), and the impact of using AXB with a grid size of 1 mm. Finally, patient‐specific quality assurance (PSQA) was performed and compared for 17 treatment plans. Results Phantom dose calculations showed a better agreement of AXB with the film measurements. In the clinical study, AXB plans exhibited lower Conformity Index and PTV V95%, higher maximum PTV dose, and lower mean and minimum PTV doses for all anatomical sites. The most notable differences were detected in regions of intense heterogeneity. AXB predicted lower doses for the OARs, while the calculation time with a grid size of 1 mm was remarkably higher. Regarding PSQA, although AAA was found to exhibit slightly higher gamma passing rates, the difference did not affect the AXB treatment plan quality. Conclusions AXB demonstrated higher accuracy than AAA in dose calculations of both phantom and clinical conditions, specifically in interface regions, making it suitable for sites with large heterogeneities. Hence, such dosimetric differences between the two algorithms should always be considered in clinical practice.

Background: Moderate hypofractionated radiotherapy (MHRT) has emerged as the preferred treatment modality for localized prostate cancer based on randomized controlled studies regarding efficacy and toxicity using contemporary radiotherapy techniques. In the setting of MHRT, available data on dosimetric parameters and late rectal toxicity are limited. Aim: To present the effects of MHRT on late rectal toxicity while conducting an extensive dosimetric analysis in conjunction with rectoscopy results. Methods: This is a prospective study including patients with intermediate-risk prostate adenocarcinoma. All patients were treated with MHRT 44 Gy in 16 fractions to the seminal vesicles and to the prostate, followed by a sequential boost to the prostate alone of 16.5 Gy in 6 fractions delivered with three-dimensional conformal radiation therapy (3DCRT). Acute and late toxicity were assessed. Endoscopy was performed at baseline, every 3 months post-therapy for the first year, and every 6 months for the year after. The Vienna Rectoscopy Score (VRS) was used to assess rectal mucosal injury related to radiotherapy. Dosimetric analysis for the rectum, rectal wall, and its subsegments (upper, mid, and low 1/3) was performed. Results: Between September 2015 and December 2019, 20 patients enrolled. Grade 1 late gastrointestinal toxicity occurred in 10% of the patients, whereas 5% had a grade ≥2. Twelve months post radiotherapy: 4 (20%) patients had VRS 1; 2 (10%) patients had VRS 2; 1(5%) patient had VRS 3. 24 months post radiotherapy, VRS 1 was observed in 4 patients (20%) and VRS 2 in 3 (15%) patients. The dosimetric analysis demonstrated noticeable variations between the rectum, rectal wall, and rectal wall subsegments. The dosimetric analysis of the rectum, rectal wall, and its mid and low segments with respect to rectoscopy findings showed that the higher dose endpoints V52.17Gy and V56.52Gy are associated with rectal mucosal injury. Conclusions: A thorough delineation of the rectal wall and its subsegments, together with the dosimetric analysis of these structures, may reduce late rectal toxicity. Dosimetric parameters such as V52.17Gy and V56.52Gy were identified to have a significant impact on rectal mucosal injury; additional dose endpoint validation and its relation to late GI toxicity is needed.

Hypofractionated radiotherapy (RT) is the standard adjuvant treatment for breast cancer patients after surgery. The recent results of the FAST-FORWARD trial on ultra-hypofractionated RT, delivered over one week, support a viable alternative regimen for early-stage breast cancer. Whether the addition of a tumor bed boost could further improve patient outcomes is still under investigation. We report the results of a single-center prospective study involving 26 early-stage (T1, 2N0) breast cancer patients treated with whole-breast RT consisting of five daily fractions of 5.2 Gy (FAST-FORWARD regimen) followed by a tumor-bed boost of three daily fractions of 3 Gy. Grade 1 early breast toxicity (skin changes and altered breast consistency) was documented in 20% of patients within the first 3 months after treatment completion. No events of acute pneumonitis were reported. Whole-breast and tumor-bed boost volumes did not affect the occurrence of breast toxicity. Minimal radiation-induced lung injury (grade 1) was noted in 95.8% of patients, while one patient (4.2%) developed grade 2 lung toxicity, which was later downgraded to grade 1 at the 12-month post-RT time point. With a median follow-up of 72 months, none of the patients presented with locoregional recurrence or distant metastases. The present study highlights the safety of a hypofractionated RT boost to the tumor bed after ultra-hypofractionated whole-breast RT. No clear evidence exists to date regarding the superiority of delivering a tumor bed boost after ultra-hypofractionated RT or the specific patient subgroups to which a boost should be prescribed.

We report photometric observations of Comet 103P/Hartley 2 during its 2023 apparition. Our campaign, conducted from August through December 2023, combined data from a global network of citizen astronomers coordinated by Unistellar and the Association Française d'Astronomie. Photometry was derived using an automated pipeline for eVscope observations in partnership with the SETI Institute and aperture photometry via AstroLab Stellar. We find that the comet's peak reduced brightness, measured at \\(G_{\\rm min} = 10.24 \\pm 0.47\\), continues a long-term fading trend since 1991. The decline in activity follows a per-apparition minimum magnitude increase of \\(\\Delta G_{\\rm min} = 0.59 \\pm 0.11\\) mag, corresponding to an approximately \\(42\\%\\) reduction in brightness each return. This trend implies that the comet's active fraction has declined by about an order of magnitude since 1991 and may indicate that Hartley 2 is no longer hyperactive by definition. The fading is consistent with progressive volatile depletion rather than orbital effects. These results offer insight into the evolutionary processes shaping Jupiter-family comets.