An evaluation of the shielding effectiveness of lead aprons used in clinics for protection against ionising radiation from novel radioisotopes

Influence of Parameters and Performance Evaluation of 3D-Printed Tungsten Mixed Filament Shields

Currently, protective clothing used in clinical field is the most representative example of efforts to reduce radiation exposure to radiation workers. However, lead is classified as a substance harmful to the human body that can cause lead poisoning. Therefore, research on the development of lead-free radiation shielding bodies is being conducted. In this study, the shielding body was manufactured by changing the size, layer, and height of the nozzle, using a 90.7% pure tungsten filament, a 3D printer material, and we compared its performance with existing protection tools. Our findings revealed that the shielding rate of the mixed tungsten filament was higher than that of the existing protective tools, confirming its potency to replace lead as the most protective material in clinical field.

Platform- and label-free detection of lead ions in environmental and laboratory samples using G-quadraplex probes by circular dichroism spectroscopy

Guanine-rich quadruplex (G-QD) are formed by conversion of nucleotides with specific sequences by stabilization of positively charged K⁺ or Na⁺. These G-QD structures differentially absorb two-directional (right- and left-handed) circularly polarized light, which can discriminate the parallel or anti-parallel structures of G-QDs. In this study, G-QDs stabilized by Pb²⁺ were analyzed by a circular dichroism (CD) spectroscopy to determine Pb²⁺ concentration in water samples. Thrombin aptamer (TBA), PS2.M, human telomeric DNA (HTG), AGRO 100, and telomeric related sequence (T2) were studied to verify their applicability as probes for platform- and label-free detection of Pb²⁺ in environmental as well as laboratory samples. Among these nucleotides, TBA and PS2.M exhibited higher binding constants for Pb²⁺, 1.20-2.04 × 10⁶/M at and 4.58 × 10⁴-1.09 × 10⁵/M at 100 micromolar and 100 mM K⁺ concentration, respectively. They also exhibited excellent selectivity for Pb²⁺ than for Al³⁺, Cu²⁺, Ni²⁺, Fe³⁺, Co²⁺, and Cr²⁺. When Pb²⁺ was spiked into an effluent sample from a wastewater treatment plant (WWTP), its existence was detected by CD spectroscopy following a simple addition of TBA or PS2.M. By the addition of TBA and PS2.M, the Pb²⁺ signals were observed in effluent samples over 0.5 micromolar (100 ppb) concentration. Furthermore, PS2.M caused a Pb²⁺-specific absorption band in the effluent sample without spiking of Pb²⁺, and could be induced to G-QD structure by the background Pb²⁺ concentration in the effluent, 0.159 micromolar concentration (3.30 ppb). Taken together, we propose that TBA and PS2.M are applicable as platform- and label-free detection probes for monitoring Pb²⁺ in environmental samples such as discharged effluent from local WWTPs, using CD spectroscopy.

Evaluations for Determination of Optimum Shields in Nuclear Medicine

Background:

¹³¹I source is widely used in the treatment of hyperthyroidism and thyroid cancers. ¹³¹I emits both beta and gamma-rays. Radiation protection is considered for gamma rays emitted by ¹³¹I. It seems no special shield against ¹³¹I source to be designed.

Objective:

This research aims to evaluate determination of optimum shields in nuclear medicine against ⁹⁹Tc^m and ¹³¹I sources by dosimetric method. Additionally, Monte Carlo simulation was used to find the optimum thickness of lead for protection against ¹³¹I source.

Material and Methods:

This is an experimental research in the field of radiation protection. A calibrated model of GraetzX5C Plus dosimeter was used to measure exposure rates passing through the shields. The efficiency of the shields was evaluated against ⁹⁹Tc^m and ¹³¹I. Furthermore, Monte Carlo simulation was used to find the optimum thickness of lead for protection against ¹³¹I source.

Results:

The findings of the dosimetric method show that the minimum and maximum efficiencies obtained by the lead apron with lead equivalent thickness of 0.25 mm and the syringe holder shields with thickness of 0.5 mm lead were 50.86% and 99.50%, respectively. The results of the simulations show that the minimum and maximum efficiencies obtained by lead thicknesses of 1 mm and 43 mm were 19.36% and 99.79%, respectively.

Conclusion:

The optimum shields against ⁹⁹Tc^m are the syringe holder shield, the tungsten syringe shield, and the lead partition, respectively. Furthermore, based on simulations, the thicknesses of 11-28 mm of lead with efficiencies between 90.6% to 99% are suggested as the optimum thicknesses to protect against ¹³¹I source.

A Novel Remote-Controlled Injection Device for T-Tube Cholangiography: A Feasibility Study in Canines

Backgroun

The purpose of this study was to develop a remote-controlled injection device for T-tube cholangiography to avoid occupational exposure.

Material/Methods

The remote-controlled injection device has 3 major components: an injection pump, a pressure sensor, and a wireless remote-control panel. The feasibility and effectiveness of this device for T-tube cholangiography was evaluated in ex vivo porcine livers using a laparoscopic training platform and in in vivo canine experiments.

Results

The contrast dye was successfully injected into the biliary tracts of the ex vivo porcine liver and canines by the designed device. The X-ray images clearly showed the anatomical structure of the bile ducts. No obvious adverse reaction was observed in the dogs during or after the procedure. All steps were controlled remotely, avoiding ionizing radiation exposure to the surgeons.

Conclusions

This novel remote-controlled injection device for T-tube cholangiography can assist operators in completing cholangiography remotely and protecting them from occupational exposure.

An Investigation to Determine an Optimum Protective Garment Material in Nuclear Medicine

AIM

The aim of this study is to find an optimum material to protect garment for protection against ⁹⁹T^cm radionuclide.

MATERIALS AND METHODS

Monte Carlo simulation code was applied to investigate radiation attenuation of 13 shielding materials including: Ba, gray Sn, white Sn, Sb, Bi, Bi₂O₃, BaSO₄, Sn/W, Sb/W, Pb and W with thicknesses of 0.5 and 1 mm to determine an optimum protective garment material in nuclear medicine against ⁹⁹Tc^m. Furthermore, the dose enhancement on the staff body was investigated for shielding materials such as tungsten and lead.

RESULTS

The findings of the simulations show that the maximum and minimum attenuation obtained with thicknesses of 1 mm W and 1 mm BaSO₄ were 96.46% and 14.2%, respectively. The results also demonstrate that tungsten does not cause any dose enhancement on staff body but this is not true for lead. Tungsten provides the highest radiation attenuation without dose enhancement on the body of staff.

CONCLUSION

Among materials evaluated, tungsten is the optimum material and it can be applied for the design of protective garment for nuclear medicine staff against ⁹⁹Tc^m.

Answers to if the Lead Aprons are Really Helpful in Nuclear Medicine from the Perspective of Spectroscopy

Wearing lead X-ray-protective aprons is a routine in nuclear medicine department in parts of China. However, the staff are often perplexed by questions such as if it is imperative to wear aprons when injecting radioactive drugs, how much radiation dosage can be shielded and if the apron will produce secondary radiation instead? To answer these questions, a semiconductor detector was employed to record different gamma and X-ray spectra with and without the lead apron or lead sheet. Then, we could estimate the signal shielding ratio to different photons for the lead apron and compare with the hospitals measured data. In general, the two results coincided well. The spectral results showed that the detrimental secondary X-rays irradiation rises when the energy of gamma rays exceeds the K absorption edge of lead (88 keV). Moreover, the aprons are not so effective for gamma rays of 364 keV emitted from 131I and 511 keV emitted from the positron radioactive nuclides. This work is purely a physical measurement in the laboratory. To the best of our knowledge, this is the first quantitative study on the level of gamma rays protection offered by the medical lead aprons and the importance of the spectroscopic measurements is discussed in this paper.