Objectives: Patients undergoing 18F-FDG PET/CT imaging are considered external radiation sources. Accurate dose rate estimates are important for conducting realistic risk assessments and performing dose reconstruction...Objectives: Patients undergoing 18F-FDG PET/CT imaging are considered external radiation sources. Accurate dose rate estimates are important for conducting realistic risk assessments and performing dose reconstruction in cases of accidental exposures. The patient radiation self-attenuation factor is assumed to be a function of the patient’s body size metrics, but we can use these metrics to predict the dose rate around the patients with accuracy. The objective of this work was first to measure the patient attenuation factor by performing direct dose rate measurements from patients undergoing PET/CT imaging studies using 18F-FDG. The second objective was to study the possible correlation between the measured dose rate constant per unit activity from the patients and their body size metrics;five metrics were tested in this work. The last objective was to measure the patients’ voiding factor. Methods: We have measured dose rates at one meter from 57 patients and noted the patient’s height (H), weight (W) and calculated patient size metrics namely: Equivalent Cylindrical Diameter (ECD), Equivalent Spherical Diameter (ESD) and the Body Mass Index (BMI). Results: The measured average dose rate was 92.2 ± 14 μSv·h-1·GBq-1 measured at one meter. Therefore, the dose rate constant of 92 μSv·h-1·GBq-1 proposed by the AAPM, TG-108 report is adequate for radiation protection purposes. There was no statistically significant correlation between the dose rate constant per unit activity and the patient body size metrics. We have measured a patient voiding factor of 0.89 ± 0.06 in comparison with 0.85 recommended by the AAPM. Conclusions: The presented data can be used by medical physicist working in nuclear medicine in formulating more accurate risk estimations resulting from radiation exposure from patients undergoing 18F-FDG PET/CT imaging.展开更多
Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at o...Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at our institution a Philips Time of Flight scanner. Our local patient’s radiation protection rules requires continuous assessment of radiation doses delivered to our patients. Purposes: The objectives of this study are to develop a weight- based facility DRLs for paediatric F-18-FDG PET-CT imaging for oncology in a large tertiary hospital and to determine whether the calculated DRLs compares with internationally published DRLs. Materials & Methods: Radiation dose data and patient demographics of two-hundreds and sixteen paediatric PET-CT oncology patients imaging procedures from one large tertiary hospital were selected and analysed in order to establish a facility paediatric DRLs. Statistical analysis was performed. Results: The PET dose reference levels ranged between [62 - 525] MBq of injected activity for a range of pediatric age groups. The CTDI<sub>vol</sub> values were between 3.5 and 16.5 mGy for all age groups. Comparison with current EANM and SNMMI recommendations of patient’s dose are discussed. Conclusion: Our pediatric PET/CT reference levels are higher than the ones reported internationally with notable variations. .展开更多
Background: The aim of this work was to examine the relationship between the estimated glomerular filtration rate (eGFR) as indicator of renal efficiency potentially related to the ability to release radioactive iodin...Background: The aim of this work was to examine the relationship between the estimated glomerular filtration rate (eGFR) as indicator of renal efficiency potentially related to the ability to release radioactive iodine from the patients bodies and the radioactive iodine whole body effective half-life (WBEHL) defined as the time taken for the administered activity to decay to half of its value for papillary thyroid cancer (PTC) patients undergoing radioactive iodine therapy (RAIT) in a tertiary care medical Centre. Methods: This retrospective observational study included seventy nine patients, sixty females and nineteen males. The patients were divided in two subgroups, those who have WBEHL of less than 11 hours (n = 51) and those with more than 11 (n = 28) hrs based on k-means clustering technique. Results: Analysis of variance (ANOVA) was used to find out if there is a statistically significant difference between the two subgroups Conclusion: There was not a statistically significant difference between the short and the longer WBEHL patients’ groups analyzed in this study. .展开更多
Objectives: The aim of this work was to initially establish both age and weight driven pediatric diagnostic reference levels (DRLs) for chest computed tomography (CT) examinations performed at tertiary care medical in...Objectives: The aim of this work was to initially establish both age and weight driven pediatric diagnostic reference levels (DRLs) for chest computed tomography (CT) examinations performed at tertiary care medical institution. Another aim was to compare the presented data with internationally published ones. This initial data shall serve as basis for establishing a national DRLs values for pediatric diagnostic CT examinations. Methods: Dosimetric indexes were collected for the chest examination for 93 patients during the past 2 years in a tertiary care medical city. Results: The results are within and below the international reported levels for chest CT in several countries. Conclusion: Continuous monitoring of the radiation doses received by the patients in computed tomography is continuous and ongoing process in order to ensure compliance and to optimize clinical imaging protocols. More extensive data acquisition and analysis are required to allow better understanding of the contributing factors leading to less patient radiation dose while preserving the clinical image quality. .展开更多
文摘Objectives: Patients undergoing 18F-FDG PET/CT imaging are considered external radiation sources. Accurate dose rate estimates are important for conducting realistic risk assessments and performing dose reconstruction in cases of accidental exposures. The patient radiation self-attenuation factor is assumed to be a function of the patient’s body size metrics, but we can use these metrics to predict the dose rate around the patients with accuracy. The objective of this work was first to measure the patient attenuation factor by performing direct dose rate measurements from patients undergoing PET/CT imaging studies using 18F-FDG. The second objective was to study the possible correlation between the measured dose rate constant per unit activity from the patients and their body size metrics;five metrics were tested in this work. The last objective was to measure the patients’ voiding factor. Methods: We have measured dose rates at one meter from 57 patients and noted the patient’s height (H), weight (W) and calculated patient size metrics namely: Equivalent Cylindrical Diameter (ECD), Equivalent Spherical Diameter (ESD) and the Body Mass Index (BMI). Results: The measured average dose rate was 92.2 ± 14 μSv·h-1·GBq-1 measured at one meter. Therefore, the dose rate constant of 92 μSv·h-1·GBq-1 proposed by the AAPM, TG-108 report is adequate for radiation protection purposes. There was no statistically significant correlation between the dose rate constant per unit activity and the patient body size metrics. We have measured a patient voiding factor of 0.89 ± 0.06 in comparison with 0.85 recommended by the AAPM. Conclusions: The presented data can be used by medical physicist working in nuclear medicine in formulating more accurate risk estimations resulting from radiation exposure from patients undergoing 18F-FDG PET/CT imaging.
文摘Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at our institution a Philips Time of Flight scanner. Our local patient’s radiation protection rules requires continuous assessment of radiation doses delivered to our patients. Purposes: The objectives of this study are to develop a weight- based facility DRLs for paediatric F-18-FDG PET-CT imaging for oncology in a large tertiary hospital and to determine whether the calculated DRLs compares with internationally published DRLs. Materials & Methods: Radiation dose data and patient demographics of two-hundreds and sixteen paediatric PET-CT oncology patients imaging procedures from one large tertiary hospital were selected and analysed in order to establish a facility paediatric DRLs. Statistical analysis was performed. Results: The PET dose reference levels ranged between [62 - 525] MBq of injected activity for a range of pediatric age groups. The CTDI<sub>vol</sub> values were between 3.5 and 16.5 mGy for all age groups. Comparison with current EANM and SNMMI recommendations of patient’s dose are discussed. Conclusion: Our pediatric PET/CT reference levels are higher than the ones reported internationally with notable variations. .
文摘Background: The aim of this work was to examine the relationship between the estimated glomerular filtration rate (eGFR) as indicator of renal efficiency potentially related to the ability to release radioactive iodine from the patients bodies and the radioactive iodine whole body effective half-life (WBEHL) defined as the time taken for the administered activity to decay to half of its value for papillary thyroid cancer (PTC) patients undergoing radioactive iodine therapy (RAIT) in a tertiary care medical Centre. Methods: This retrospective observational study included seventy nine patients, sixty females and nineteen males. The patients were divided in two subgroups, those who have WBEHL of less than 11 hours (n = 51) and those with more than 11 (n = 28) hrs based on k-means clustering technique. Results: Analysis of variance (ANOVA) was used to find out if there is a statistically significant difference between the two subgroups Conclusion: There was not a statistically significant difference between the short and the longer WBEHL patients’ groups analyzed in this study. .
文摘Objectives: The aim of this work was to initially establish both age and weight driven pediatric diagnostic reference levels (DRLs) for chest computed tomography (CT) examinations performed at tertiary care medical institution. Another aim was to compare the presented data with internationally published ones. This initial data shall serve as basis for establishing a national DRLs values for pediatric diagnostic CT examinations. Methods: Dosimetric indexes were collected for the chest examination for 93 patients during the past 2 years in a tertiary care medical city. Results: The results are within and below the international reported levels for chest CT in several countries. Conclusion: Continuous monitoring of the radiation doses received by the patients in computed tomography is continuous and ongoing process in order to ensure compliance and to optimize clinical imaging protocols. More extensive data acquisition and analysis are required to allow better understanding of the contributing factors leading to less patient radiation dose while preserving the clinical image quality. .
