Timer error as well as its convention is very important for dose accuracy during irradiation. This paper determines the timer error of irradiators at Secondary Standard Dosimetry Laboratory (SSDL) in Nigeria. The irra...Timer error as well as its convention is very important for dose accuracy during irradiation. This paper determines the timer error of irradiators at Secondary Standard Dosimetry Laboratory (SSDL) in Nigeria. The irradiators are Cs-137 OB6 irradiator and X-ray irradiators at the Protection level SSDL;and Co-60 irradiator at the Therapy Level SSDL. PTW UNIDOS electrometer and LS01 Ionization chamber were used at the Protection Level to obtain doses for both Cs-137 OB6 and X-ray irradiators while an IBA farmer type ionization chamber and an IBA DOSE 1 electrometer were used at the Protection Level SSDL. Single/multiple exposure method and graphical method were used in the determination of the timer error for the three irradiators. The timer error obtained for Cs-137 OB6 irradiator was 0.48 ± 0.01 s, the timer error for the X-ray irradiator was 0.09 ± 0.01 s while the timer error obtained for GammaBeam X200 was 1.21 ± 0.04 s. It was observed that the timer error is not affected by source to detector distance. It was also observed that the timer error of Co-60 Gamma X200 irradiator is increasing with the age of the machine. Source to detector distance and field size do not contribute towards the timer error of the irradiators. The timer error of the Co-60 Gamma X200 irradiator (the only irradiator among the irradiators with a pneumatic system) increases with the age of the irradiator.展开更多
BACKGROUND:The study aimed to determine the frequency of enoxaparin dosing errors for patients who had a measured emergency department(ED)weight compared to those who did not have a measured ED weight,and to determine...BACKGROUND:The study aimed to determine the frequency of enoxaparin dosing errors for patients who had a measured emergency department(ED)weight compared to those who did not have a measured ED weight,and to determine if demographic variables(e.g.,weight,height,age,Englishspeaking,race)impact the likelihood of receiving an inappropriate dose.METHODS:This is a retrospective,electronic chart review of patients who received a dose of enoxaparin in the ED between January 1,2008 and July 1,2013.We identified all patients>18 years who received a dose of enoxaparin while in the ED,were admitted,and had at least one inpatient weight within the first four days of hospitalization.Patients were excluded if they received enoxaparin for prophylaxis or a dose of more than 1.25mg/kg.RESULTS:A total of 1,944 patients were included.Patients were more likely to experience an error if they did not have a measured ED weight.Over-doses of>10mg were more likely to occur in patients without a measured ED weight.Patients with no documented ED weight or with a staffestimated ED weight were more likely to experience a dosing error than those with a patient-stated weight.Patients were more likely to experience an error if their first inpatient weight was more than 96kg,they were more than 175-cm tall,or were English speaking.CONCLUSION:Dosing errors are more likely to occur when patients are not weighed in the ED.Modifications to current workflows to incorporate weighing those patients who receive weightdosed medications may be warranted.展开更多
Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation dete...Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation detectors such as cerium chloride doped with lanthanum bromide(LaBr_3(Ce)), thallium doped with cesium iodide(sI(Tl)), thallium doped with sodium iodide(NaI(Tl)),and high-purity germanium(HPGe) primarily use the spectroscopy-dose rate function(G(E)) to achieve the accurate measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)). However, the spectroscopy-dose rate function has been rarely measured for a CZT detector. In this study, we performed spectrum measurement using a hemispherical CZT detector in a radiation protection standards laboratory. The spectroscopy-dose rate function G(E) of the CZT detector was calculated using the least-squares method combined with the standard dose rate at the measurement position. The results showed that the hemispherical CZT detector could complete the measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)) by using the G(E) function at energies between 48 keV and 1.25 MeV, and the relative intrinsic errors were, respectively, controlled within ± 2. 3 and ± 2. 1%.展开更多
文摘Timer error as well as its convention is very important for dose accuracy during irradiation. This paper determines the timer error of irradiators at Secondary Standard Dosimetry Laboratory (SSDL) in Nigeria. The irradiators are Cs-137 OB6 irradiator and X-ray irradiators at the Protection level SSDL;and Co-60 irradiator at the Therapy Level SSDL. PTW UNIDOS electrometer and LS01 Ionization chamber were used at the Protection Level to obtain doses for both Cs-137 OB6 and X-ray irradiators while an IBA farmer type ionization chamber and an IBA DOSE 1 electrometer were used at the Protection Level SSDL. Single/multiple exposure method and graphical method were used in the determination of the timer error for the three irradiators. The timer error obtained for Cs-137 OB6 irradiator was 0.48 ± 0.01 s, the timer error for the X-ray irradiator was 0.09 ± 0.01 s while the timer error obtained for GammaBeam X200 was 1.21 ± 0.04 s. It was observed that the timer error is not affected by source to detector distance. It was also observed that the timer error of Co-60 Gamma X200 irradiator is increasing with the age of the machine. Source to detector distance and field size do not contribute towards the timer error of the irradiators. The timer error of the Co-60 Gamma X200 irradiator (the only irradiator among the irradiators with a pneumatic system) increases with the age of the irradiator.
文摘BACKGROUND:The study aimed to determine the frequency of enoxaparin dosing errors for patients who had a measured emergency department(ED)weight compared to those who did not have a measured ED weight,and to determine if demographic variables(e.g.,weight,height,age,Englishspeaking,race)impact the likelihood of receiving an inappropriate dose.METHODS:This is a retrospective,electronic chart review of patients who received a dose of enoxaparin in the ED between January 1,2008 and July 1,2013.We identified all patients>18 years who received a dose of enoxaparin while in the ED,were admitted,and had at least one inpatient weight within the first four days of hospitalization.Patients were excluded if they received enoxaparin for prophylaxis or a dose of more than 1.25mg/kg.RESULTS:A total of 1,944 patients were included.Patients were more likely to experience an error if they did not have a measured ED weight.Over-doses of>10mg were more likely to occur in patients without a measured ED weight.Patients with no documented ED weight or with a staffestimated ED weight were more likely to experience a dosing error than those with a patient-stated weight.Patients were more likely to experience an error if their first inpatient weight was more than 96kg,they were more than 175-cm tall,or were English speaking.CONCLUSION:Dosing errors are more likely to occur when patients are not weighed in the ED.Modifications to current workflows to incorporate weighing those patients who receive weightdosed medications may be warranted.
文摘目的探究鼻咽癌患者调强放射治疗(IMRT)中应用锥形束计算机断层扫描(CBCT)和机载影像系统(on Board Image,OBI)分析对摆位误差的影响。方法筛选2018年7月~2021年7月桂林医学院附属医院接诊的140例鼻咽癌患者进行分组对照研究,所有患者均依据数字表法随机分为CBCT组和OBI组,每组各70例患者。比较两组的摆位误差及放射剂量差异,分析CBCT、OBI系统在降低鼻咽癌患者IMRT的摆位误差中的价值。结果(1)相比于校正前,校正后两组的摆位误差均明显降低,并且相比于OBI组,校正后CBCT组的摆位误差明显更低(P均<0.05);(2)在降低鼻咽癌患者IMRT的摆位误差中,CBCT的ROC曲线下面积(area under curve,AUC)、特异度、敏感度与OBI对比均明显升高(Z=2.241,P<0.000);(3)相比于校正前,校正后两组的计划靶区边界(margins of planning target volume,MPTV)值均明显降低,并且相比于OBI组,校正后CBCT组的MPTV值明显更低(P均<0.05);(4)两组脑干、脊髓、晶状体和视交叉的实际剂量高于计划剂量,且CBCT组低于OBI组,差异有统计学意义(P<0.05)。结论鼻咽癌患者应用CBCT、OBI系统分析均可校正摆位误差,提高患者的摆位与调强放疗精确度。CBCT、OBI系统可以通过减少摆位误差,有可能进一步缩小计划靶区范围,从而减少靶区临近危机器官的照射剂量的临床目的。CBCT的作用更明显,是值得临床推广应用的方案。
基金supported by the National Key Scientific Instruments to Develop Dedicated(Nos.2013YQ090811 and 2016YFF0103800)
文摘Since the room-temperature detector CdZnTe(CZT) has advantages in terms of detection efficiency,energy resolution, and size, it has been extensively used to detect X-rays and gamma-rays. So far, nuclear radiation detectors such as cerium chloride doped with lanthanum bromide(LaBr_3(Ce)), thallium doped with cesium iodide(sI(Tl)), thallium doped with sodium iodide(NaI(Tl)),and high-purity germanium(HPGe) primarily use the spectroscopy-dose rate function(G(E)) to achieve the accurate measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)). However, the spectroscopy-dose rate function has been rarely measured for a CZT detector. In this study, we performed spectrum measurement using a hemispherical CZT detector in a radiation protection standards laboratory. The spectroscopy-dose rate function G(E) of the CZT detector was calculated using the least-squares method combined with the standard dose rate at the measurement position. The results showed that the hemispherical CZT detector could complete the measurement of air kerma rate(K_a) and ambient dose equivalent rate(H*(10)) by using the G(E) function at energies between 48 keV and 1.25 MeV, and the relative intrinsic errors were, respectively, controlled within ± 2. 3 and ± 2. 1%.
