Monte Carlo simulation and analysis of eye lens dose of the first operator in interventional therapy / 中国辐射卫生

Objective To establish a model for estimating the eye lens dose of the first operator in interventional therapy based on the Monte Carlo simulation, and to provide a scientific basis for the rapid and accurate evaluation of the eye lens dose for radiation workers in interventional therapy. Methods Based on the MIRD phantom and eye model for adult Chinese males, the MCNPX program was used to establish the physical model to calculate the spatial distribution of radiation field and eye lens dose for the first operator. A GR200 Type A LiF (Mg, Cu, P) thermoluminescence dosimeter was used for experimental measurement to verify the simulation results. Results Monte Carlo simulation and experimental measurements showed that the spatial distribution of radiation field was symmetrical. Compared with the measured doses, the errors of the simulated eye lens dose of the first operator were between −8.3% and 7.3%. The dose of the left eye lens was higher than that of the right eye. Conclusion The Monte Carlo model constructed in this study initially realizes the simulation of eye lens dose of the first operator in interventional therapy. In the future, the model will be further optimized based on irradiation parameters such as exposure time, tube voltage, tube current, and projection direction used in clinic practice, so as to more accurately evaluate the eye lens dose of interventional therapy staff.

A study and analysis of eye lens dose levels of medical staff during interventional cardiology procedures / 中国辐射卫生

Objective To analyze the eye lens equivalent dose levels of doctors during interventional cardiology procedures and identify related influential factors. Methods Twenty interventional specialists were selected from a cardiovascular specialty hospital. The cumulative equivalent doses to their eye lens during operations were monitored, and equipment-related parameters (fluoroscopy time, dose area product value [DAP], and entrance skin dose[ESD]), operation types, and operators’ positions were recorded. Results The annual equivalent doses to the eye lens of seven doctors exceeded 20 mSv. There was a linear correlation between the weekly number of operations and the equivalent dose to the eye lens (R2 = 0.457, P = 0.001). The mean eye lens equivalent dose per operation was 17.1 μSv, showing linear correlations with fluoroscopy time, DAP values, and ESD values (R2 = 0.427, 0.206, and 0.237, respectively, P < 0.05). The fluoroscopy time, DAP value, ESD value, and eye lens equivalent dose during percutaneous coronary intervention (PCI) were significantly higher than those during coronary angiography (t = −3.226, −3.108, −3.061, and −2.667, respectively, P < 0.03). Conclusion The annual equivalent doses to the eye lens are relatively high in interventional radiologists, some of whom may have values higher than the latest dose limit (20 mSv) suggested by the International Commission on Radiological Protection. Attention should be paid to operators performing PCI, and the workload optimization is necessary in practical operations to avoid unnecessary fluoroscopy time and reduce the eye lens doses of the operators.

Measurement of eye and lens doses in the presence and absence of shield during whole brain irradiation

Aim: The aim was to measure doses of eyes and lenses in the presence and absence of shield during whole brain irradiation (WBI). In addition, the dose calculations accuracy of radiation therapy dose plan treatment planning system (TPS) in dose calculation of the eyes and lenses in WBI was evaluated. Materials and Methods: To measure the eyes and lenses doses during WBI, an inhomogeneous phantom of human head was used. Then, the eyes and lenses doses in the presence and absence of shield were measured by EBT3 film. Results: In single fraction with 200 cGy to reference point, average doses received by the left and right eyes in the absence of shield were 20 ± 1.5 and 22 ± 1.0 cGy, respectively, and for the left and right eyes in the presence of shield were 18 ± 2.2 and 21 ± 2 cGy, respectively. In addition, the average dose received by the left and right lenses in the absence of shield were 19.5 ± 0.5 and 18.5 ± 0.5 cGy, respectively, and for the left and right lenses in the presence of shield were 20.5 ± 1.5 and 19.5 ± 1.5 cGy, respectively. The results showed the TPS compared to the film underestimates doses for the eyes and lenses. Conclusion: The average dose received by the eyes and lenses during WBI were estimated around 9–11% of prescribed dose. According to the results, there is probability of radiation-induced cataractogenesis during WBI. By investigating the effect of shield on the lenses and eyes doses, using shield during WBI is not recommended. In addition, the results showed dose calculation accuracy of the TPS for the estimation of doses received by the eyes and lenses during WBI is not acceptable

Establishment of standards of Hp(3) for the calibration of eye-lens dose equivalent dosimeters / 中国医学装备

Objective:To establish the X-ray standard was used to calibrate Hp(3) dosimeter in order to satisfy the requirement of eye-lens dose equivalents for the radiological occupational staff.Methods:The conventional values (Hp(3)) on the reference point of the narrow beams of X-ray fields were obtained by means of the product of air kerma (Kair) and the conversion coefficients (hp(3,ɑ)) recommended by ICRP116 recommendation. And these researches can be used by standard ionization chamber dosimeter. Finally, provided the conventional true value Hp(3) at calibrate point.Results:The standards and calibration program of calibrations eye-lens dose equivalent dosimeter were established under the X-ray radiation field. The detection error between slab phantom recommended by ISO and head phantom recommended by the 116th publication of ICRP was lower when the TLD was used to detect result.Conclusions:The standards for calibration Hp(3) dosimeters can satisfy the requirement of calibration for radiological occupational staff. It also provides theoretical foundation for detection data that assessed Hp(3) dosimeters and then improves trace ability and reliability of detection data of Hp(3) in national radiation supervision and inspection network.

Evaluation of radiation dose to working operator in three types of interventional fluoroscopic procedures / 中华放射医学与防护杂志

Objective To assess the level of radiation exposures of operators in three typical types of interventional fluoroscopic procedures.Methods Alderson Radiation Therapy (ART) phantom was used to stimulate the practices of diagnosis and therapy using TLDs for dose measurement.The radiation exposures of eye lens, neck, and breast were measured when the lead shielding of machine was on/off and the equivalent dose and effective dose to the eye lens were estimated.Results Radiation exposure of head was obviously reduced by 85% -90% when the lead shielding was on.The doses in different procedures were different.In cerebral angiography the dose equivalent of eye len was the highest in the three procedures.The annual effective dose for the operators was smaller in peripheral vascular interventions than that in cardiovascular interventional therapy and that in cerebral angiography.Conclusions The operators involved in intervention will receive an annual effective dose of less than 20 mSv as recommended by the ICRP under the protection conditions provided by the current study, except for eye lens.Attention should be paid to the protection of the eyes of operators.