en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;"><span style="font-size:10pt"><span style="text-justify:newspaper"><span style="text-kashida-space:50%"><span style="line-height:119%"><span style="font-family:Calibri"><span style="color:black"><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Background:</span></span></span></span></span></span> <span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">This study evaluates the distance and angular dependence of polycrystalline semiconductor-based dosimeters (PSDs) using lead (II) iodide (PbI₂) (PbI₂ PSD) and lead (II) oxide (PbO) (PbO PSD) for Ir-192 brachytherapy source. Experimental measurements were compared with Monte Carlo (MC) simulations to verify the dosimeters&#39; performance and accuracy. </span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-GB">Materials and Methods: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">PSDs were fabricated using PbI₂ and PbO as photoconductive materials, with a thin-film deposition process ensuring uniformity. Distance dependence was assessed by measuring dosimeter responses at source-to-surface distances ranging from 1 cm to 8 cm at 0.25 cm intervals, while angular dependence was evaluated at angles from 0&deg; to 60&deg; in 15&deg; increments. MC simulations using the Geant4 Application for Tomographic Emission (GATE) v9.1 were conducted under identical conditions to validate the experimental measurements. </span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-GB">Results: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">The experimental and simulated data demonstrated a strong agreement with the inverse-square law, with determination coefficient (R&sup2;) exceeding 0.98 for PbI₂ and PbO PSDs. The distance at which the signal intensity dropped by 50% (D₅₀) for measurements and simulations was 1.493 cm and 1.487 cm for PbI₂ PSD, respectively, and 1.488 cm and 1.481 cm for PbO PSD. Angular dependence analysis showed a decrease in response with increasing angle, with PbO PSD exhibiting slightly larger discrepancies (maximum difference of 5.48%) compared to PbI₂ PSD (maximum difference of 4.56%) between measurements and simulations. </span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-GB">Conclusion: </span></span></span></span></span></span><span lang="en-GB" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:black"><span style="language:en-GB">PbI₂ and PbO PSDs demonstrated predictable distance and angular dependence, closely aligning with MC simulations. However, angular correction factors may be necessary to improve dosimetric accuracy in clinical applications.</span></span></span></span></span></span></span></span></span></span></div> Dosimeters, semiconductors, brachytherapy, iridium-192 radioisotope, Monte Carlo simulation, quality assurance. 317 322 http://ijrr.com/browse.php?a_code=A-10-1-1496&slc_lang=en&sid=1 M.J. Han 7900319475328460033381 7900319475328460033381 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea S.W. Kang 7900319475328460033382 7900319475328460033382 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea K.Y. Eom 7900319475328460033383 7900319475328460033383 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea I.A. Kim 7900319475328460033384 7900319475328460033384 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea J.S. Kim 7900319475328460033385 7900319475328460033385 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea B. Lee 7900319475328460033386 7900319475328460033386 No Department of Radiation Oncology, Inha University Hospital, Incheon 22332, Republic of Korea W. Cho 7900319475328460033387 7900319475328460033387 No Department of Radiation Oncology, Seoul National University Boramae Medical Center, Seoul 07061, Republic of Korea J.B. Chung 7900319475328460033388 7900319475328460033388 No Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea