The magnitude of radiation dose imparted to patients who underwent Head Computed Tomography examination in a large tertiary hospital in South-Southern Nigeria has been estimated. CT-ExPO dosimetry software was used to...The magnitude of radiation dose imparted to patients who underwent Head Computed Tomography examination in a large tertiary hospital in South-Southern Nigeria has been estimated. CT-ExPO dosimetry software was used to determine the effective and organ doses to the head region of 40 adult patients. Scanning parameters were retrieved from the CT monitor for both contrast-enhanced and non-contrast head CT examinations. The tube potential ranged from 100 kVp to 120 kVp, while the mAs ranged from 127 mAs to 202 mAs. The mean values of the volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) for the contrast-enhanced Head CT examination were 166.4 ± 39.6 mGy and 3568.6 ± 756.1 mGy·cm, respectively, while for the non-contrast examination they were 86.6 ± 30.4 mGy and 2102.3 ± 870.3 mGy·cm, respectively. The effective doses were higher for the contrast-enhanced study than for the non-contrast study by a factor of 1.6. Results were compared with the European Union reference doses and other published data and were found to be higher. Doses to the organs which comprise of brain, red bone marrow, thyroid and eye lens were also estimated. The high variation in the doses in this study may be due to differences in imaging protocols such as large range of mAs and scan lengths and also the algorithm of the scanner.展开更多
The aim of this study was to investigate the organ doses of patients undergoing computed tomography (CT) examination using the wide bore General Electric (GE) “Light Speed RT” unit. The head, chest and pelvic region...The aim of this study was to investigate the organ doses of patients undergoing computed tomography (CT) examination using the wide bore General Electric (GE) “Light Speed RT” unit. The head, chest and pelvic regions of the Rando-phantom were scanned with 120 kV, 200 mA, and 2.5 mm slice thickness for helical and axial modes. Thermoluminescent Dosimeter (TLD) pairs were used for the dosimetry of 10 organs. TL-counts were converted to dose by using CTDIcenter dose on CT-phantom. For the calculation of the organ doses, the ImPACT software was utilized by entering CTDIair (100 mAs) in small and large field of view (26.43 and 21.17 mGy respectively). The in-field dose ranges in helical and axial modes were 64.3 - 38 mGy and 47.6 - 19.7 mGy in head, 48.3 - 14.1 mGy and 34.1 - 10 mGy in chest, 28.4 - 10.2 mGy and 21 - 8.5 mGy in pelvic, respectively. The organ doses from software and TLD were compared and tailored as the in-field and the out-field radiation. First results showed that the organ dose was relatively higher in the helical mode on both direct and indirect measurement. The in-field organ dose differences between TLD and software were seen. In helical and axial modes, the dose differences ranged from +1 to +13.3 and -8.3 to +9.6 mGy for head exam, +1.1 to +15.3 and +0.3 to +9.1 mGy for chest, and -21.7 to +1.9 and -15.5 to +1.8 mGy for pelvic. The availability of this program for organ dose calculations by measuring CTDIair value for CT device used in the radiotherapy would be considered valuable.展开更多
Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is im...Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is important to prevent adverse events in normal tissues. In the present study, we evaluated the impact of variation in bladder volume on the doses to various organs. A total of 35 patients underwent definitive radiotherapy at Saitama Medical Center. A Light Speed RT16 (GE Healthcare) was used for planning and to obtain examination CT images. Such images were acquired after 4 - 6 days of planning CT image acquisition. The IMRT plans were optimized using the planning CT data to satisfy the dose constraints set by our in-house protocols for the PTV and the OARs. The dose distributions were then re-calculated using the same IMRT beams, and checked on examination CT images. It was clear that bladder volume affected the doses to certain organs. We focused on the prostate, bladder, rectum, small bowel, and large bowel. Regression coefficients were calculated for variables that correlated strongly with bladder volume (p < 0.05). We found that variation in bladder volume [cm<sup>3</sup>] predicted deviations in the bladder V<sub>70Gy</sub>, V<sub>50Gy</sub>, and V<sub>30Gy</sub> [%];the maximum dose to the small bowel [cGy];and the maximum dose to the large bowel [cGy]. The regression coefficients were -0.065, -0.125, -0.180, -10.22, and -9.831, respectively. We evaluated the impacts of such variation on organ doses. These may be helpful when checking a patient’s bladder volume before daily IMRT for localized prostate cancer.展开更多
Background: Treatment of Cervical cancer includes a combination of external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT). ICBT helps to boost radiation dose to primary disease. Organs like rectum, ...Background: Treatment of Cervical cancer includes a combination of external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT). ICBT helps to boost radiation dose to primary disease. Organs like rectum, bladder, sigmoid and small bowel lie close to the cervix region and these organs receive dose from EBRT as well as ICBT and we want to know the dose to these organ at risk (OAR). Materials & Methods: Dosimetric details of 174 ICBT applications done in 58 patients were retrospectively analysed. All patients received EBRT dose of 50.4 Gy in 28 fractions. All patients had ICBT, three sessions with 7 Gy prescribed to point A. Dosimetric data including dose to right and left point A and dose to OARs were recorded from Oncentra Planning System. Results: Mean dose to point A on right side was 6.89 Gy and left side was 6.91 Gy. Mean D2cc dose to rectum, bladder, sigmoid and small bowel was 3.5 Gy, 5.25 Gy, 4.75 Gy and 4.2 Gy respectively. Mean EQD2 dose combining EBRT and ICBT in point A was 78.7 Gy on right side and 79 Gy on left side. Mean EQD2 doses to D2cc of rectum, bladder, sigmoid and small bowel was 62 Gy, 74.4 Gy, 70.5 Gy and 66.5 Gy respectively. Conclusion: From the results of this dosimetric study it is evident that OARs like rectum, sigmoid, bladder & bowel are receiving only acceptable doses of radiation using point A prescribed CT based ICBT planning. Hence with regards to OAR doses, CT based ICBT planning with dose prescribed to point A is a feasible option.展开更多
Children are more sensitive to radiation than adults, so radiation protection in paediatric radiology deserves special attention. This work estimates the effective doses and body organ doses due to chest examinations ...Children are more sensitive to radiation than adults, so radiation protection in paediatric radiology deserves special attention. This work estimates the effective doses and body organ doses due to chest examinations in infants and paediatrics. Two examination incidences, AP and PA for chest X-ray exposures were evaluated and compared with respect to the radiographic technique employed. This study was carried out in three paediatric hospitals in Sudan. The age intervals considered were 0 - 1 year, 1 - 5 years, 5 - 10 years and 10 - 15 years. The results obtained for organ doses and effective doses were calculated using a software package developed by the Radiological Protection Centre of the Saint George’s Hospital, London. Effective dose values were also evaluated considering weight intervals from 1 - 10 kg, 10 - 20 kg, 20 - 30 kg and 30 - 40 kg. Large discrepancies were encountered between the three hospitals, probably due to the different radiographic technique employed, calibration and maintenance of the X-ray equipment, technicians’ expertise, processing conditions.展开更多
The study was intended to highlight functional outcome and survival advantage when High Dose Rate (HDR) interstitial implant was used for anterior 2/3rd tongue, either as a primary or as boost depending upon stage of ...The study was intended to highlight functional outcome and survival advantage when High Dose Rate (HDR) interstitial implant was used for anterior 2/3rd tongue, either as a primary or as boost depending upon stage of disease. Materials and Methods: Fifty-one patients with squamous cell carcinoma of anterior 2/3rd tongue received interstitial brachytherapy either as primary or as boost with Iridium 192 remote after loading high dose rate (Microselectron or Gamma MediX) machines from November 2008 to September 2013. Age group ranged from 32 to 73 years, mean 52.1. Of these 51, 37 were males and 14 were females. 8 patients belonged to Stage I, 18 from Stage II and 28 patients were Stage III. Stage I patients received primary brachytherapy alone of dose 38.50 Gy to 40 Gy and fraction dose ranged from 250 cGy to 350 cGy. Stage II and Stage III patients received external beam radiation of dose 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. Stage III patients received concurrent chemotherapy with Injection Cisplatin along with external beam radiotherapy 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. 55% of patients were habituated to tobacco and alcohol in one form or the other or both. Surprisingly 45% of patients were nonsmokers and non-alcoholic. Results: Follow-up period ranged from eight months to sixty months. 42 patients had complete response. 9 patients had residual disease. 2 patients died due to non-cancerous cause though they had excellent local control, one with pulmonary tuberculosis and the other with massive Myocardial Infarction. 2 patients died due to disease progression. Overall complete response rate was 82.35%. Those patients who had good coverage index and conformal index had good response compared to those patients with lesser these values. Conclusion: It is surprising to observe from the study that oral cavity cancers are not uncommon in non-smokers and non-alcoholics. Overall complete response of 82% is comparable to any other study quoted in literature. Surgery offers same cure rate but at the rate of organ loss and functional impairment. Organ preservation with good functional outcome is possible in radiotherapy unlike surgery. This study proves brachytherapy can be considered as a surrogate to surgery in early stage tongue cancers with good functional outcome and with lesser morbidity.展开更多
The main objectives were to (1) calculate the total volatile organic compounds (TVOCs) inhalation dose, (2) analyze the proportions of human’s inhaled contaminant dose from different sources, and (3) present a newly ...The main objectives were to (1) calculate the total volatile organic compounds (TVOCs) inhalation dose, (2) analyze the proportions of human’s inhaled contaminant dose from different sources, and (3) present a newly defined ratio of relative inhalation dose level (RIDL) to assess indoor air quality (IAQ). A user defined function based on CFD (computational fluid dynamics) was developed, which integrated human motion model with TVOCs emission model in a high sidewall air supply ventilation mode. Based on simulation results of 10 cases, it is shown that the spatial concentration distribution of TVOCs is affected by human motion. TVOCs diffusion characteristic of building material is the most effective way to impact the TVOCs inhalation dose. From the RIDL index, case A-2 has the most serious IAQ problem, while case D-1 is of the best IAQ.展开更多
文摘The magnitude of radiation dose imparted to patients who underwent Head Computed Tomography examination in a large tertiary hospital in South-Southern Nigeria has been estimated. CT-ExPO dosimetry software was used to determine the effective and organ doses to the head region of 40 adult patients. Scanning parameters were retrieved from the CT monitor for both contrast-enhanced and non-contrast head CT examinations. The tube potential ranged from 100 kVp to 120 kVp, while the mAs ranged from 127 mAs to 202 mAs. The mean values of the volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) for the contrast-enhanced Head CT examination were 166.4 ± 39.6 mGy and 3568.6 ± 756.1 mGy·cm, respectively, while for the non-contrast examination they were 86.6 ± 30.4 mGy and 2102.3 ± 870.3 mGy·cm, respectively. The effective doses were higher for the contrast-enhanced study than for the non-contrast study by a factor of 1.6. Results were compared with the European Union reference doses and other published data and were found to be higher. Doses to the organs which comprise of brain, red bone marrow, thyroid and eye lens were also estimated. The high variation in the doses in this study may be due to differences in imaging protocols such as large range of mAs and scan lengths and also the algorithm of the scanner.
文摘The aim of this study was to investigate the organ doses of patients undergoing computed tomography (CT) examination using the wide bore General Electric (GE) “Light Speed RT” unit. The head, chest and pelvic regions of the Rando-phantom were scanned with 120 kV, 200 mA, and 2.5 mm slice thickness for helical and axial modes. Thermoluminescent Dosimeter (TLD) pairs were used for the dosimetry of 10 organs. TL-counts were converted to dose by using CTDIcenter dose on CT-phantom. For the calculation of the organ doses, the ImPACT software was utilized by entering CTDIair (100 mAs) in small and large field of view (26.43 and 21.17 mGy respectively). The in-field dose ranges in helical and axial modes were 64.3 - 38 mGy and 47.6 - 19.7 mGy in head, 48.3 - 14.1 mGy and 34.1 - 10 mGy in chest, 28.4 - 10.2 mGy and 21 - 8.5 mGy in pelvic, respectively. The organ doses from software and TLD were compared and tailored as the in-field and the out-field radiation. First results showed that the organ dose was relatively higher in the helical mode on both direct and indirect measurement. The in-field organ dose differences between TLD and software were seen. In helical and axial modes, the dose differences ranged from +1 to +13.3 and -8.3 to +9.6 mGy for head exam, +1.1 to +15.3 and +0.3 to +9.1 mGy for chest, and -21.7 to +1.9 and -15.5 to +1.8 mGy for pelvic. The availability of this program for organ dose calculations by measuring CTDIair value for CT device used in the radiotherapy would be considered valuable.
文摘Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is important to prevent adverse events in normal tissues. In the present study, we evaluated the impact of variation in bladder volume on the doses to various organs. A total of 35 patients underwent definitive radiotherapy at Saitama Medical Center. A Light Speed RT16 (GE Healthcare) was used for planning and to obtain examination CT images. Such images were acquired after 4 - 6 days of planning CT image acquisition. The IMRT plans were optimized using the planning CT data to satisfy the dose constraints set by our in-house protocols for the PTV and the OARs. The dose distributions were then re-calculated using the same IMRT beams, and checked on examination CT images. It was clear that bladder volume affected the doses to certain organs. We focused on the prostate, bladder, rectum, small bowel, and large bowel. Regression coefficients were calculated for variables that correlated strongly with bladder volume (p < 0.05). We found that variation in bladder volume [cm<sup>3</sup>] predicted deviations in the bladder V<sub>70Gy</sub>, V<sub>50Gy</sub>, and V<sub>30Gy</sub> [%];the maximum dose to the small bowel [cGy];and the maximum dose to the large bowel [cGy]. The regression coefficients were -0.065, -0.125, -0.180, -10.22, and -9.831, respectively. We evaluated the impacts of such variation on organ doses. These may be helpful when checking a patient’s bladder volume before daily IMRT for localized prostate cancer.
文摘Background: Treatment of Cervical cancer includes a combination of external beam radiotherapy (EBRT) with intracavitary brachytherapy (ICBT). ICBT helps to boost radiation dose to primary disease. Organs like rectum, bladder, sigmoid and small bowel lie close to the cervix region and these organs receive dose from EBRT as well as ICBT and we want to know the dose to these organ at risk (OAR). Materials & Methods: Dosimetric details of 174 ICBT applications done in 58 patients were retrospectively analysed. All patients received EBRT dose of 50.4 Gy in 28 fractions. All patients had ICBT, three sessions with 7 Gy prescribed to point A. Dosimetric data including dose to right and left point A and dose to OARs were recorded from Oncentra Planning System. Results: Mean dose to point A on right side was 6.89 Gy and left side was 6.91 Gy. Mean D2cc dose to rectum, bladder, sigmoid and small bowel was 3.5 Gy, 5.25 Gy, 4.75 Gy and 4.2 Gy respectively. Mean EQD2 dose combining EBRT and ICBT in point A was 78.7 Gy on right side and 79 Gy on left side. Mean EQD2 doses to D2cc of rectum, bladder, sigmoid and small bowel was 62 Gy, 74.4 Gy, 70.5 Gy and 66.5 Gy respectively. Conclusion: From the results of this dosimetric study it is evident that OARs like rectum, sigmoid, bladder & bowel are receiving only acceptable doses of radiation using point A prescribed CT based ICBT planning. Hence with regards to OAR doses, CT based ICBT planning with dose prescribed to point A is a feasible option.
文摘Children are more sensitive to radiation than adults, so radiation protection in paediatric radiology deserves special attention. This work estimates the effective doses and body organ doses due to chest examinations in infants and paediatrics. Two examination incidences, AP and PA for chest X-ray exposures were evaluated and compared with respect to the radiographic technique employed. This study was carried out in three paediatric hospitals in Sudan. The age intervals considered were 0 - 1 year, 1 - 5 years, 5 - 10 years and 10 - 15 years. The results obtained for organ doses and effective doses were calculated using a software package developed by the Radiological Protection Centre of the Saint George’s Hospital, London. Effective dose values were also evaluated considering weight intervals from 1 - 10 kg, 10 - 20 kg, 20 - 30 kg and 30 - 40 kg. Large discrepancies were encountered between the three hospitals, probably due to the different radiographic technique employed, calibration and maintenance of the X-ray equipment, technicians’ expertise, processing conditions.
文摘The study was intended to highlight functional outcome and survival advantage when High Dose Rate (HDR) interstitial implant was used for anterior 2/3rd tongue, either as a primary or as boost depending upon stage of disease. Materials and Methods: Fifty-one patients with squamous cell carcinoma of anterior 2/3rd tongue received interstitial brachytherapy either as primary or as boost with Iridium 192 remote after loading high dose rate (Microselectron or Gamma MediX) machines from November 2008 to September 2013. Age group ranged from 32 to 73 years, mean 52.1. Of these 51, 37 were males and 14 were females. 8 patients belonged to Stage I, 18 from Stage II and 28 patients were Stage III. Stage I patients received primary brachytherapy alone of dose 38.50 Gy to 40 Gy and fraction dose ranged from 250 cGy to 350 cGy. Stage II and Stage III patients received external beam radiation of dose 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. Stage III patients received concurrent chemotherapy with Injection Cisplatin along with external beam radiotherapy 44 Gy/200cGy per fraction for 22 fractions followed by spinal cord sparing for 6 Gy/200cGy per fraction for 3 fractions. Brachytherapy boost of dose 21 Gy was delivered after external beam radiation. 55% of patients were habituated to tobacco and alcohol in one form or the other or both. Surprisingly 45% of patients were nonsmokers and non-alcoholic. Results: Follow-up period ranged from eight months to sixty months. 42 patients had complete response. 9 patients had residual disease. 2 patients died due to non-cancerous cause though they had excellent local control, one with pulmonary tuberculosis and the other with massive Myocardial Infarction. 2 patients died due to disease progression. Overall complete response rate was 82.35%. Those patients who had good coverage index and conformal index had good response compared to those patients with lesser these values. Conclusion: It is surprising to observe from the study that oral cavity cancers are not uncommon in non-smokers and non-alcoholics. Overall complete response of 82% is comparable to any other study quoted in literature. Surgery offers same cure rate but at the rate of organ loss and functional impairment. Organ preservation with good functional outcome is possible in radiotherapy unlike surgery. This study proves brachytherapy can be considered as a surrogate to surgery in early stage tongue cancers with good functional outcome and with lesser morbidity.
基金Projects(2006BAJ02A08, 2006BAJ02A05) supported by the National Science and Technology Pillar Program Project during the 11th Five-Year Plan PeriodProject(2007-209) supported by the Excellent Youth Teacher of Ministry of Education of China
文摘The main objectives were to (1) calculate the total volatile organic compounds (TVOCs) inhalation dose, (2) analyze the proportions of human’s inhaled contaminant dose from different sources, and (3) present a newly defined ratio of relative inhalation dose level (RIDL) to assess indoor air quality (IAQ). A user defined function based on CFD (computational fluid dynamics) was developed, which integrated human motion model with TVOCs emission model in a high sidewall air supply ventilation mode. Based on simulation results of 10 cases, it is shown that the spatial concentration distribution of TVOCs is affected by human motion. TVOCs diffusion characteristic of building material is the most effective way to impact the TVOCs inhalation dose. From the RIDL index, case A-2 has the most serious IAQ problem, while case D-1 is of the best IAQ.