Purpose: The study aimed to measure the radiation-absorbed dose, effective dose, and associated risks of radiation-induced cancers during chest computed tomography (CT) imaging procedures at Square Hospital, Dhaka, Bangladesh. Methods: A total of 23 patients were examined using a 64-slice CT scanner and thermolumi nescence dosimeters. The dose-length product was recorded and converted into an equivalent effective dose using age-dependent conversion coefficients for multi-slice CT as provided by the European Guidelines. Organ doses were further converted into lifetime attributable risks (LARs) for cancer incidence and mortality based on data from the Biological Effects of Ionizing Radiation VII (BEIR VII) report. Results: The effective dose ranged from 3.1 millisieverts (mSv) to approximately 35.3 mSv. The mean LAR for cancer incidence was 20.6 cases per 100,000 males and 69.3 cases per 100,000 females. The LAR for cancer mortality was 21.5 cases per 100,000 males and 62.0 cases per 100,000 females. Female patients were found to face significantly higher risks than male patients. Conclusions The results highlight a noticeable increase in LAR for both cancer incidence and mortality due to chest CT examinations, particularly for female patients. These findings underscore the importance of carefully evaluating the risks associated with CT imaging procedures.

Purpose: To assess the effect of gold nanoparticles (GNPs) on enhancing radiation doses in brachytherapy and evaluate their potential as radiosensitizers. Methods: A Monte Carlo simulation was conducted to determine the radiation dose enhancement factor (DEF) of GNPs in brachytherapy using Iridium-192 (¹⁹²Ir) or Iodine-125 (¹²⁵I). The simulations compared the depth-dose curves of ¹⁹²Ir and ¹²⁵I in both water and tissue phantoms. A spherical tumor model with a radius of 3.5 cm surrounded by normal tissue was used for DEF calculation.The radioactive source was positioned at the center of the tumor and the DEF was calculated for GNP concentrations of 7, 18, and 30 mg/g present only in the tumor tissue. Results: The differences in depth doses between the water and tissue phantoms were more noticeable for ¹⁹²Ir than for ¹²⁵I. For ¹⁹²Ir, the DEF of the GNPs ranged from 1.6 to 2.8, depending on the concentration of GNP. For ¹²⁵I, the DEF was less than 1. Conclusions GNPs were confirmed to enhance the radiation dose in brachytherapy when using 192 Ir.

Purpose: This study aimed to present a novel method for estimating the effective atomic number(Zeff ) using dual-energy computed tomography (DECT) designed to improve accuracy andstreamline clinical workflows by reducing computational complexity. Methods: The proposed model leverages the DECT-derived mass attenuation coefficients without detailed compositional analysis. By incorporating additional parameters into the conventional Rutherford model, such as exponential and trigonometric functions, the model effectively capturescomplex variations in attenuation, enabling precise Zeff estimation. Model fitting was performedusing dual-energy data and evaluated using the percentage difference in error rates. Results: Compared with the Rutherford model, which recorded a maximum error rate of 0.55%, the proposed model demonstrated a significantly lower maximum error rate of 0.15%, highlightingits precision. Zeff estimates for various materials closely matched the reference values, confirmingthe improved accuracy of the model. Conclusions The proposed DECT-based model provides a practical and efficient approach to Zeff estimation, with potential applications in radiation oncology, particularly for accurate stopping power ratio calculations in proton and heavy ion therapies.

Purpose: The study aimed to measure the radiation-absorbed dose, effective dose, and associated risks of radiation-induced cancers during chest computed tomography (CT) imaging procedures at Square Hospital, Dhaka, Bangladesh. Methods: A total of 23 patients were examined using a 64-slice CT scanner and thermolumi nescence dosimeters. The dose-length product was recorded and converted into an equivalent effective dose using age-dependent conversion coefficients for multi-slice CT as provided by the European Guidelines. Organ doses were further converted into lifetime attributable risks (LARs) for cancer incidence and mortality based on data from the Biological Effects of Ionizing Radiation VII (BEIR VII) report. Results: The effective dose ranged from 3.1 millisieverts (mSv) to approximately 35.3 mSv. The mean LAR for cancer incidence was 20.6 cases per 100,000 males and 69.3 cases per 100,000 females. The LAR for cancer mortality was 21.5 cases per 100,000 males and 62.0 cases per 100,000 females. Female patients were found to face significantly higher risks than male patients. Conclusions The results highlight a noticeable increase in LAR for both cancer incidence and mortality due to chest CT examinations, particularly for female patients. These findings underscore the importance of carefully evaluating the risks associated with CT imaging procedures.

Purpose: To assess the effect of gold nanoparticles (GNPs) on enhancing radiation doses in brachytherapy and evaluate their potential as radiosensitizers. Methods: A Monte Carlo simulation was conducted to determine the radiation dose enhancement factor (DEF) of GNPs in brachytherapy using Iridium-192 (¹⁹²Ir) or Iodine-125 (¹²⁵I). The simulations compared the depth-dose curves of ¹⁹²Ir and ¹²⁵I in both water and tissue phantoms. A spherical tumor model with a radius of 3.5 cm surrounded by normal tissue was used for DEF calculation.The radioactive source was positioned at the center of the tumor and the DEF was calculated for GNP concentrations of 7, 18, and 30 mg/g present only in the tumor tissue. Results: The differences in depth doses between the water and tissue phantoms were more noticeable for ¹⁹²Ir than for ¹²⁵I. For ¹⁹²Ir, the DEF of the GNPs ranged from 1.6 to 2.8, depending on the concentration of GNP. For ¹²⁵I, the DEF was less than 1. Conclusions GNPs were confirmed to enhance the radiation dose in brachytherapy when using 192 Ir.

Purpose: This study aimed to present a novel method for estimating the effective atomic number(Zeff ) using dual-energy computed tomography (DECT) designed to improve accuracy andstreamline clinical workflows by reducing computational complexity. Methods: The proposed model leverages the DECT-derived mass attenuation coefficients without detailed compositional analysis. By incorporating additional parameters into the conventional Rutherford model, such as exponential and trigonometric functions, the model effectively capturescomplex variations in attenuation, enabling precise Zeff estimation. Model fitting was performedusing dual-energy data and evaluated using the percentage difference in error rates. Results: Compared with the Rutherford model, which recorded a maximum error rate of 0.55%, the proposed model demonstrated a significantly lower maximum error rate of 0.15%, highlightingits precision. Zeff estimates for various materials closely matched the reference values, confirmingthe improved accuracy of the model. Conclusions The proposed DECT-based model provides a practical and efficient approach to Zeff estimation, with potential applications in radiation oncology, particularly for accurate stopping power ratio calculations in proton and heavy ion therapies.

Purpose: The study aimed to measure the radiation-absorbed dose, effective dose, and associated risks of radiation-induced cancers during chest computed tomography (CT) imaging procedures at Square Hospital, Dhaka, Bangladesh. Methods: A total of 23 patients were examined using a 64-slice CT scanner and thermolumi nescence dosimeters. The dose-length product was recorded and converted into an equivalent effective dose using age-dependent conversion coefficients for multi-slice CT as provided by the European Guidelines. Organ doses were further converted into lifetime attributable risks (LARs) for cancer incidence and mortality based on data from the Biological Effects of Ionizing Radiation VII (BEIR VII) report. Results: The effective dose ranged from 3.1 millisieverts (mSv) to approximately 35.3 mSv. The mean LAR for cancer incidence was 20.6 cases per 100,000 males and 69.3 cases per 100,000 females. The LAR for cancer mortality was 21.5 cases per 100,000 males and 62.0 cases per 100,000 females. Female patients were found to face significantly higher risks than male patients. Conclusions The results highlight a noticeable increase in LAR for both cancer incidence and mortality due to chest CT examinations, particularly for female patients. These findings underscore the importance of carefully evaluating the risks associated with CT imaging procedures.