Determination of scatter radiation to the breast during lumbosacral x-ray examination using thermoluminescence dosimeter

Objective: Exposure to ionizing radiation during radiographic examination is associated with some biological effects. The study was aimed to determine the amount of scatter radiation to the breast during lumbosacral x-ray examination. Materials and Methods: The study was a prospective, cross-sectional study carried out among 60 women referred for Lumbosacral spine radiography from September 2019 to December 2019. Ethical approval was granted by the hospital ethical committee. A single-phase mobile X-ray unit was used to dispense the radiation while a thermoluminescent dosimeter (TLD) chip was used to measure the radiation dose. The TLD chip was attached to the peri-areolar region of the left breast and held in place by a transparent adhesive tape. The TLD was carefully enclosed in a black polythene sachet before and after the investigation to shield it from background radiation. After the investigation the TLD,s were sent to the Centre for Energy Research and Training (CERT) for reading and annealing. Results: The mean age and BMI of participants were 55.32±12.35years and 29.70±7.09kg/m2 respectively. The cumulative mean (±SD) ESD to the breast was 3.87±0.87mGy. The highest scatter radiation dose was observed in the age group 60-69 years. Pearson’s correlation showed a week correlation between age and ESD. Conclusion: The study showed that there were scatter radiations to the breast during lumbosacral X-Ray investigations which was was lowest among the age group 50-59years. No significant difference was seen between AP and lateral positions. The cancer risk was 1 in 6,000 indicating that there might be needed to shield the breast while performing lumbosacral X-ray.

Improving Monitoring of Radiation Pulses at the Industrial Facilities

In case of accidents at the industrial facilities, where there are devices that are a source of ionizing radiation, a significant part of the fission products is in a vaporous and aerosol state. There is no sharp drop in the radiation levels, which means that the terrain can be damaged for a long time and become uninhabitable. To assess the damage and eliminate the consequences of exposure to a hard radiation pulse, it is required to have such systems that register the dose fields in real time with a high temporal resolution and do not require regular verification and reference to the reference fields. To solve the problem, it is proposed to measure the dose rate of pulsed radiation by the induced conductivity in the air. This makes it possible to obtain the absolute values of the dose rate without reference to the reference fields, with a time resolution of 1·108 per second. The relationship between conductivity of the ionized air and the dose rate is given by means of experimentally determined constants: mobility of the electrons in the air and the lifetime of electrons before they stick to oxygen molecules in the air considering participation of the third particle. Proposed method is based on the microwave sounding of the highly ionized air. This allows to significantly expand the range of application of the ionization methods up to 1·108 Sv/s for photon radiation and to provide nanosecond time resolution. In the present experiments, the time dependence of the dose rate on time obtained by high-frequency probing was measured, and the dose per pulse was found by integrating over time. Measurement results were compared with the readings of a certified integral thermoluminescent dosimeter based on LiF. Measurement results indicate agreement within 20–30 %. High-frequency detectors can be used as part of information and measurement systems to alert about possible emergencies. The method allows obtaining final information in real time and forming management teams on mitigation of emergency situations consequences.

Occupational Radiation Exposure and Validity of National Dosimetry Registry among Korean Interventional Radiologists

The national dose registry (NDR) contains essential information to help protect radiation workers from radiation-related health risks and to facilitate epidemiological studies. However, direct validation of the reported doses has not been considered. We investigated the validity of the NDR with a personal dosimeter monitoring conducted among Korean interventional radiologists. Among the 56 interventional radiologists, NDR quarterly doses were compared with actively monitored personal thermoluminescent dosimeter (TLD) doses as standard measures of validation. We conducted analyses with participants categorized according to compliance with TLD badge-wearing policies. A correlation between actively monitored doses and NDR doses was low (Spearman ρ = 0.06), and the mean actively monitored dose was significantly higher than the mean NDR dose (mean difference 0.98 mSv) in all participants. However, interventional radiologists who wore badges irregularly showed a large difference between actively monitored doses and NDR doses (mean difference 2.39 mSv), and participants who wore badges regularly showed no apparent difference between actively monitored doses and NDR doses (mean difference 0.26 mSv). This study indicated that NDR data underestimate the actual occupational radiation exposure, and the validity of these data varies according to compliance with badge-wearing policies. Considerable attention is required to interpret and utilize NDR data based on radiation workers’ compliance with badge-wearing policies.

OPTIMIZING THE TLD-100H READOUT SYSTEM UNDER VARIOUS RADIOACTIVE I-131 DOSES VIA THE REVISED TAGUCHI DYNAMIC QUALITY LOSS FUNCTION

The TLD-100H readout system performance under various radioactive I-131 exposure doses was optimized by four key factors via the revised Taguchi dynamic quality loss function. Taguchi dynamic analysis and the orthogonal array reorganizing the essential factors are crucial for the optimization of the thermoluminescent dosimeter (TLD) readout system given strict criteria of multiple irradiated environments and long-term exposure for calibrated TLDs. Accordingly, 96 TLD-100H chips were selected and randomly categorized into three batches with eight groups (four TLD chips in each group). Four factors, namely (1) initial temperature, (2) heating rate, (3) maximal temperature, and (4) TLD preheat time before reading were organized into eight combinations according to Taguchi suggestion, whereas each factor was preset at two levels. All 96 [Formula: see text] chips were put in three concentric circles with 30, 60, and 90 cm radii for 48 h, surrounding the radioactive 150[Formula: see text]mCi ([Formula: see text][Formula: see text]MBq) I-131 capsule and exposed to the cumulative doses of 88.2, 18.6, and 8.6[Formula: see text]mSv for the respective radii, accordingly. The TLD readings obtained from each group were analyzed to derive the sensitivity, coincidence, and reproducibility, then those were reorganized to draw four fish-bone-plots for the optimization. The optimal option for the TLD readout system implied the combination of A1 (a [Formula: see text]C initial temperature), B1 (a [Formula: see text]C/s heating rate), C1 (a [Formula: see text]C maximal temperature), and D2 (a 15[Formula: see text]s preheat time), which was further verified by the follow-up measurements. The dominant factors were A (initial temperature) and B (heating rate), whereas C (maximal temperature) and D (preheat time) were minor and provided negligible contributions to the system performance optimization.

Efficient reading of thermoluminescent dosimeter signals using semiconductor detectors

The aim of this experimental work was to examine whether semiconductor photodetectors may be applied for the efficient reading of thermoluminescent dosimeter (TLD) signals. For this purpose, a series of experiments have been performed at the Department of Physics, Warsaw University of Technology, in cooperation with the Central Laboratory for Radiological Protection (CLOR). Specifically, the measurement system proposed here has been designed to detect a signal from TLDs that use a semiconductor detector operating in conditions analogous to those met when using commercial devices equipped with a classic photomultiplier. For the experimental tests, the TLDs were irradiated with a beam of 137Cs radiation in the accredited Laboratory for Calibration of Dosimetric and Radon Instruments. Eventually, a comparison of the results obtained with a semiconductor detector (ID120) and a commercial TLD reader with a photomultiplier tube (RADOS) were made.

Extremity Exposure with 99mTc - labelled Radiopharmaceuticals in Diagnostic Nuclear Medicine

Background: Extremity exposures may raise the risk of cancer induction among radiographers involved in preparation and administration of technetium-99m labelled radiopharmaceuticals. Objective: To estimate finger doses on radiographers at a South African tertiary hospital. Methods: Adhesive tape was used to securely fix a calibrated thermoluminescent dosimeter (TLD) on fingertips and bases of ring and index fingers of both hands of five radiographers who prepared and administered technetium-99m labelled radiopharmaceuticals. Rubber gloves were worn to avoid TLD contamination. TLDs doses were read with a Harsaw TLD Reader (Model 3500) after a week. Results: Five radiographers prepared and administered technitium-99m labelled radiopharmaceuticals (activity range; 78.20 GBq - 132.78 GBq during one-week measurement period). A radiographer handling 132.78 GBq received 4.74±0.52 mSv on both hands; 5.52, 4.55, 5.11 and 4.60 mSv on the fingertip of the index finger of the dominant hand (FIDH), fingertip of the ring finger of the dominant hand (FRDH), fingertip of the index finger of the non-dominant hand (FINDH) and fingertip of the ring finger of the non-dominant hand (FRNDH) respectively. The respective doses received on the finger bases were 4.50 mSv, 4.60, 4.21 and 3.48 mSv. The radiographer handling 78.20 GBq received 0.85±0.18 mSv on both hands, 1.04, 1.17, 0.77 and 1 mSv for the FIDH, FRDH, FINDH and FRNDH respectively while respective doses for the bases were 0.8, 0.9, 0.6 and 0.8 mSv. Conclusion: The extremity exposures were below the annual limit (500 mSv). However, the use of syringe shields could still reduce the finger doses further.