2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility
| Format: | General Document |
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| building | INTELEK Repository |
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| collectionurl | https://intelek.unisza.edu.my/intelek/pages/search.php?search=!collection8803 |
| copyright | Copyright©PWB2026 |
| country | Malaysia |
| date | 2025-09-07 |
| format | General Document |
| id | 17476 |
| institution | UniSZA |
| originalfilename | 17476_ba8c34809e5af93.pdf |
| person | Adila Hanim Aminordin Sabri |
| recordtype | oai_dc |
| resourceurl | https://intelek.unisza.edu.my/intelek/pages/view.php?ref=17476 |
| sourcemedia | Server storage Scanned document |
| spelling | 17476 https://intelek.unisza.edu.my/intelek/pages/view.php?ref=17476 https://intelek.unisza.edu.my/intelek/pages/search.php?search=!collection8803 General Document Malaysia Library Staff (Top Management) Library Staff (Management) Library Staff (Support) Terengganu Faculty of Health Sciences English application/pdf 1.5 Microsoft® Word 2016 224 Public Access Server storage Scanned document Universiti Sultan Zainal Abidin Universiti Sultan Zainal Abidin Dissertations, Academic Copyright©PWB2026 Thesis 2025-09-07 Adila Hanim Aminordin Sabri 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility Radiation Therapy Brachytherapy Ir-192 source Co-60 source Photon dosimetry Scattered Radiation Radiation Shielding Dose Optimization Monte Carlo Simulation PHITS code hermoluminescent Dosimeter (TLD) Clinical Dosimetry Occupational Dosimetry Radiation — Dosage Radiation — Safety Measures Shielding (Radiation) Medical Physics Radiation therapy requires particle accelerators or high dose rate (HDR) gamma sources such as Ir-192 and Co-60 for treating tumors using ionizing radiation. Photon dosimetry is indispensable in designing radiation shielding for irradiation facilities. Proper control of radiation doses is essential to prevent hazards caused by exposure. Clinical dosimetry (patient monitoring) and occupational dosimetry (staff monitoring) are key to dose optimization. Photon attenuation must be considered to protect those outside treatment areas, as concrete walls near gamma sources contribute to scattered radiation. Low-energy scattered radiation can be absorbed by non-targeted body parts, posing a risk to patients. Thus, this study aims to optimize scattered radiation from Ir-192 sources in a brachytherapy room. In a brachytherapy room irradiated with an Ir-192 source, spatial distributions of photon dose rates were measured and calculated for dose distribution both inside and outside the room; at the control panel area, waiting area in front of the lead door, and at the corridor. Measurements of dose distribution were taken using a thermoluminescent dosimeter (LiF TLD-100) placed on the surfaces of the concrete walls and barriers of the irradiation room. Calculations were conducted using the Particle and Heavy Ion Transport Code System (PHITS), considering the detailed model of the Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia brachytherapy room, and the radiation source used in measurements. The direct measured (75.504 mSv/h) and calculated (75.327 mSv/h) photon doses from an Ir-192 source with an activity of 10.3 Curie demonstrated strong agreement, confirming that the validation criteria were satisfied. Photon fluxes were significantly attenuated in the outside area, particularly in front of the entrance door and control console, ensuring the safety of the workers. However, an edge effect was observed on the left side of the sliding lead door. To reduce this edge effect at the entrance door, adding a 3-mm thick lead layer on the surface of the concrete wall on the left doorstop is recommended. The walls and floor closest to the gamma source contributed significantly to the scattered radiation at the patient location, accounting for approximately 7.4% of unnecessary additional dose. Measures were needed to reduce the reflected dose component to the patient, particularly as patients may undergo repeated radiation procedures. The addition of a 2-mm inner lead layer proved adequate to shield almost 92% of the reflected photons from the Ir-192 source to the patient location. If Co-60 is replaced with Ir-192, the dose at the control console and in front of the entrance maze increases by a factor of approximately 60 with existing wall and lead door thickness. In justification of medical exposure, any unnecessary exposure to the patient must be avoided. The existing wall thickness of our brachytherapy room was sufficient to reduce the dose rate at the control console and in front of the entrance door by up to 95% of the initial dose. The edge effect at the entrance can be effectively addressed by adding a thin lead layer to the surface of the concrete wall on the left side of the doorstop. uuid:4b46fc78-a708-4f24-ae4a-678866121263 17476_ba8c34809e5af93.pdf |
| spellingShingle | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| state | Terengganu |
| subject | Dissertations, Academic Radiation — Dosage Radiation — Safety Measures Shielding (Radiation) Medical Physics |
| summary | Radiation therapy requires particle accelerators or high dose rate (HDR) gamma sources such as Ir-192 and Co-60 for treating tumors using ionizing radiation. Photon dosimetry is indispensable in designing radiation shielding for irradiation facilities. Proper control of radiation doses is essential to prevent hazards caused by exposure. Clinical dosimetry (patient monitoring) and occupational dosimetry (staff monitoring) are key to dose optimization. Photon attenuation must be considered to protect those outside treatment areas, as concrete walls near gamma sources contribute to scattered radiation. Low-energy scattered radiation can be absorbed by non-targeted body parts, posing a risk to patients. Thus, this study aims to optimize scattered radiation from Ir-192 sources in a brachytherapy room. In a brachytherapy room irradiated with an Ir-192 source, spatial distributions of photon dose rates were measured and calculated for dose distribution both inside and outside the room; at the control panel area, waiting area in front of the lead door, and at the corridor. Measurements of dose distribution were taken using a thermoluminescent dosimeter (LiF TLD-100) placed on the surfaces of the concrete walls and barriers of the irradiation room. Calculations were conducted using the Particle and Heavy Ion Transport Code System (PHITS), considering the detailed model of the Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia brachytherapy room, and the radiation source used in measurements. The direct measured (75.504 mSv/h) and calculated (75.327 mSv/h) photon doses from an Ir-192 source with an activity of 10.3 Curie demonstrated strong agreement, confirming that the validation criteria were satisfied. Photon fluxes were significantly attenuated in the outside area, particularly in front of the entrance door and control console, ensuring the safety of the workers. However, an edge effect was observed on the left side of the sliding lead door. To reduce this edge effect at the entrance door, adding a 3-mm thick lead layer on the surface of the concrete wall on the left doorstop is recommended. The walls and floor closest to the gamma source contributed significantly to the scattered radiation at the patient location, accounting for approximately 7.4% of unnecessary additional dose. Measures were needed to reduce the reflected dose component to the patient, particularly as patients may undergo repeated radiation procedures. The addition of a 2-mm inner lead layer proved adequate to shield almost 92% of the reflected photons from the Ir-192 source to the patient location. If Co-60 is replaced with Ir-192, the dose at the control console and in front of the entrance maze increases by a factor of approximately 60 with existing wall and lead door thickness. In justification of medical exposure, any unnecessary exposure to the patient must be avoided. The existing wall thickness of our brachytherapy room was sufficient to reduce the dose rate at the control console and in front of the entrance door by up to 95% of the initial dose. The edge effect at the entrance can be effectively addressed by adding a thin lead layer to the surface of the concrete wall on the left side of the doorstop. |
| title | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| title_full | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| title_fullStr | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| title_full_unstemmed | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| title_short | 2026_Monte Carlo-Based Optimization Of Shielding Design for Scattered Photon Dose Reduction in Ir-192 And Co-60 Brachytherapy Facility |
| title_sort | 2026_monte carlo-based optimization of shielding design for scattered photon dose reduction in ir-192 and co-60 brachytherapy facility |