Homi Bhabha National Institute

One fourth of the patients receiving SBRT to prostate and pelvis develop mild to moderate acute enteritis. In this study, we aim to study bowel dosimetry for different methods of bowel delineation in patients with and without acute bowel toxicity after whole-pelvic SBRT (WP-SBRT).

In this prospective study, patients with high-risk prostate cancer treated with WP-SBRT were identified. Patients with acute bowel toxicity (CTCAE v5.0) were included as cases while those without were controls. All the patients had previously received 35-36.25 Gy in 5 fractions to the prostate and 25 Gy in 5 fractions to the pelvis. The bowel was contoured on the planning CT scan using seven different methods, namely- bowel bag (BB), small bowel loop (SB), large bowel loop (LB), combined bowel loop (BL) and bowel loops with margins (BL + 0.5 cm, BL + 1 cm and BL + 1.5 cm). The original clinically used plan was applied to all the contouring methods and dose-volume parameters studied.

A total of 102 patients treated with WP-SBRT were screened and only those with properly documented acute toxicity were included for further analysis. While none of the patients had grade 3 bowel toxicity, 23 (22.5 %) patients had grade 1-2 acute enteritis, and 23 patients without were selected as cases and controls respectively. On visual assessment, the composite dose volume histogram (DVH) were similar for cases and controls for all the delineation methods studied. Objectively, the volume of the bowel structures receiving 7 Gy, 14 Gy, and 25 Gy did not show any statistically significant difference between cases and controls. One in five patients treated with WP-SBRT using bowel bag dose constraints of V₇ < 1500 cc, V₁₄ < 500 cc and V₂₅ < 50 cc had acute enteritis.

There was no significant difference in planned bowel doses for different bowel delineation methods in patients with prostate cancer treated with WP-SBRT with or without acute bowel toxicity.

The seminal Haldane model brings up a paradigm beyond the quantum Hall effect to look for a plethora of topological phases in the honeycomb and other lattices. Here we dwell into this model considering a full parameter space in the presence of spin–orbit interaction as well as Zeeman field such that the flavour of Kane-Mele model is invoked. Adopting this extended Haldane model as an example, we elucidate, in a transparent manner, a number of topological features in a pedagogical manner. First, we describe various first order topological insulator phases and their characterizations while explaining various anomalous quantum Hall effects and quantum spin Hall effects in the extended Haldane model. Second, we demonstrate the concepts of higher order topological insulator phases along with the topological invariants in the anisotropic limit of the extended Haldane model. At the end, we discuss various open issues involving emergent or extended symmetries that might lead to a broader understanding of various topological phases and the associated criteria behind their emergence.

Alk. hydrolysis of organic radioactive liquid waste, specifically, spent PUREX solvent, is an established process that yields three distinct phases: n-dodecane (top), water-soluble organic phosphate (di-Bu phosphate) along with butanol (middle, a product of alk. hydrolysis), and unreacted alkali (bottom).Managing the middle layer (ML) poses significant challenges due to its high phosphate content (300-350 g/L), substantial radioactivity (gross α 515-1,500 Bq/mL, gross β-γ 1,453-2,500 Bq/mL), and complex compositionVarious methodologies have been tested to destroy organic components or sep. radionuclides from the ML, including dilution and dispersion, microfiltration, direct cementation, chem. precipitation, and pyrolysis.Among these methods, pyrolysis has successfully demonstrated complete mineralization, converting sodium di-Bu phosphate to Na3PO4 and effectively separating and isolating the radioactive content from the ML using an indigenously designed pyrolyzer.In this work, comprehensive studies on the thermal, spectroscopic, and radiometric properties of the ML, as well as the immobilization of residues, were conducted by employing a thermogravimetry analyzer (TG-DSC) coupled with an evolved gas analyzer, Fourier-transform IR spectroscopy, high-purity germanium (HP-Ge) gamma (γ) spectrometry, and the International Atomic Energy Agency (IAEA) 28-day chem. durability test.The resulting cement waste form contained 20 wt% undissolved residue from ML pyrolysis and separated radionuclides achieved a leachability index (L) greater than 6.This indicates that the cemented waste form meets the acceptance criteria, ensuring safe and effective long-term disposal.