Digital Dosimeter Research Articles

Evaluation of mercury (II) iodide dosimeter for digital quality assurance in intracavitary radiotherapy

In intracavitary radiotherapy, it is essential to verify the correct location of radiation source among quality control items because an incorrect location will irradiate an unnecessary dose to normal tissues. As a basic study of digital line dosimeters, this study fabricated a unit cell dosimeter based on polycrystalline mercury (II) iodide (HgI2) and compared its performance with a diode. The study result showed that for reproducibility, the relative standard deviation (RSD) was 1.21%, satisfying the RSD evaluation criterion of within 1.5%. Considering linearity, the coefficient of determination R2 showed an excellent result of 0.9997. Regarding the evaluation of distance dependence, it showed a similar trend in general with a difference of 0.035 cm for intensity 50% when compared with the inverse square value. The angular dependence gradually decreased in intensity as the angle increased, showing a difference of up to 25%. This study suggests the applicability of a digital dosimeter for brachytherapy quality control by evaluating the performance of the HgI2 dosimeter. However, to develop it into a quality assurance (QA) dosimeter, correction factor for sensitivity according to angle should be applied. This study on dosimeter for candidate photoconductor materials can be used as basic data in all areas using radiation.

ESTIMASI DOSIS RADIASI YANG DITERIMA PASIEN PADA PEMERIKSAAN THORAX PA

Background : Radiation dose received by patients during medical radiology examination varied among practices. This is due to difference in techniques, filter, and equipment used during examinations. This study aims to determine the value of facilities Diagnostic Reference Level (fDRL) in Radiology hospitals district Buleleng and comparison of the 75th percentile value of radiation dose received by adult Thorax PA patients with the standards established by BAPETEN.
 Methods: This type of research uses a quantitative method with a survey conducted at the Radiology Installation of Buleleng Regency Hospital in February 2020. The population of this study was all patients who underwent radiographic examination of Thorax PA adults (over 15 years). While the sample in this study was 30 patients with Thorax PA radiography examination adult (over 15 years). Absorbent dose measurement data is carried out directly with a digital dosimeter measuring device and then processed using SPSS.
 Results and Conclusion: The results of this study obtained the value of facilities Diagnostic Reference Level for examination of adult PA Thorax in Radiology Installation of Buleleng Regency Hospital is 0.0275 mGy and the percentile value of 75 absorbent doses received by PA thorax patients adult in Radiology Installation of Buleleng Regency Regional Hospital is 0.0275 mGy where the dose Radiation absorption received by PA thorax patients has met the standards set by BAPETEN in the Indonesian Diagnostic Reference Level (IDRL) 2019 radiation absorbed dose received by adult thorax PA patients, which is 0.4 mGy.

Verification, analytical validation and clinical validation (V3) of wearable dosimeters and light loggers.

Light exposure is an important driver and modulator of human physiology, behavior and overall health, including the biological clock, sleep-wake cycles, mood and alertness. Light can also be used as a directed intervention, e.g., in the form of light therapy in seasonal affective disorder (SAD), jetlag prevention and treatment, or to treat circadian disorders. Recently, a system of quantities and units related to the physiological effects of light was standardized by the International Commission on Illumination (CIE S 026/E:2018). At the same time, biometric monitoring technologies (BioMeTs) to capture personalized light exposure were developed. However, because there are currently no standard approaches to evaluate the digital dosimeters, the need to provide a firm framework for the characterization, calibration, and reporting for these digital sensors is urgent. This article provides such a framework by applying the principles of verification, analytic validation and clinical validation (V3) as a state-of-the-art approach for tools and standards in digital medicine to light dosimetry. This article describes opportunities for the use of digital dosimeters for basic research, for monitoring light exposure, and for measuring adherence in both clinical and non-clinical populations to light-based interventions in clinical trials.

Decommissioning procedure and induced activation levels, calculations and measurements in an 18 MeV medical cyclotron

The present article describes the decommissioning of a self-shielded 18 MeV medical cyclotron IBA Cyclone 18/9 after 14 years of operation. A Monte Carlo simulation of the possible nuclear reactions was performed in order to plan the decommissioning activities. During the cyclotron dismantling, the activities of the cyclotron components, concrete wall and floor samples were measured. Residual activities were analysed by means of an HPGe detector and liquid scintillation counting, and compared with simulation data. Dosimetry of the staff involved in the decommissioning procedure was monitored by individual TL dosimeters and/or digital dosimeter. The cyclotron component analysis confirmed the presence of gamma and pure beta emitters, 22Na, 54Mn, 60Co, 65Zn, 207Bi, 55Fe, 63Ni at different values of specific activity, depending on the positioning of the sample point and on the alloy of the sampled part. In these components the presence of gamma and pure beta emitters was measured 5 years after the shutdown at levels far above clearance limits as defined by the ‘Recommended radiological protection criteria for the recycling of metals from the dismantling of nuclear installations’ (RP89) guidelines. The simulation, carried out by FLUKA Code (version 2020.0.5) on the cyclotron components, provided good agreement with measurements, with a maximum discrepancy of the same order as the uncertainties. Four engineers of the cyclotron maintenance staff were involved in the dismounting of the hottest components and rigging of the cyclotron in the deposit 6 months after shutdown and two engineers were involved during the drilling phase 3.5 years after shutdown. The measured dose from external exposure of the involved staff was lower than 100 μSv person−1 during the first phase and lower than 20 μSv person−1 during the final drilling phase. Measured doses from intake were negligible. In conclusion, the decommissioning of the 18 MeV cyclotron does not represent a risk for the involved staff, but, due to the presence of long-lived radioisotopes, the cyclotron components are to be treated as low level radioactive waste, and stored in an authorised storage area for at least 25 years after shutdown.

Development and evaluation of lead(II) iodide-based polycrystalline digital dosimeter for quality assurance in brachytherapy

Brachytherapy is a cancer treatment that involves intensively irradiating a tumor by placing a sealed radioactive isotope inside the body. Determining the position of the source through accurate quality assurance (QA) is important, because brachytherapy uses radioactive isotope sources with high dose rates. However, in clinical practice, the source position is determined with the naked eye through the use of a ruler, autoradiograph, video monitor, etc., which yields inaccurate results. Therefore, in this study, a lead (II) iodide (PbI2) based polycrystalline digital dosimeter that can measure the relative dose was developed for the QA of the brachytherapy device, and its applicability was evaluated in terms of reproducibility, linearity, percentage interval distance (PID), and angular dependence. Reproducibility evaluation yielded a relative standard deviation value of 1.41%, which satisfied the evaluation criterion of 1.5%. The linearity evaluation yielded an R2 value of 0.9993, which satisfied the evaluation criterion of 0.9990. The PID evaluation revealed that, as the distance from the source increased, the signal decreased according to the inverse-square law. When the PbI2-based digital dosimeter was rotated up to 45°, a difference of up to 13.20% in the angular dependence was observed. Thus, the dosimeter fabricated in this experiment met all the criteria of the aforementioned evaluations. Therefore, it is considered to be highly applicable as a dosimeter for the QA of brachytherapy devices.

Evaluation of two-dimensional dosimeter based on thallium (I) bromide for measurement of surface dose in radiotherapy

In radiotherapy, side effects can occur on the skin because each patient's skin has a different level of sensitivity to radiation. Therefore, in clinical practice, point dose is measured to verify skin doses, although there is a problem, in that it is difficult to analyse the dose distribution for the body surface area. In this study, we constructed a film dosimeter based on polycrystalline thallium (I) bromide, evaluated its performance, and analysed the electrical properties according to the number of bending cycles to evaluate the mechanical flexibility. Further, an array dosimeter was constructed, and the dose distribution was analysed to evaluate the clinical effectiveness. As a result of the performance evaluation, reproducibility, linearity, and dose-rate dependence all satisfied the evaluation criteria. Percent depth dose showed similar results, and a difference of 0.027 when the slope of the depth in the range of 20–10 cm was compared with that of the thimble chamber. With regard to mechanical flexibility, as the number of bending cycles increased, the sensitivity tended to decrease. The clinical efficacy evaluation showed that the difference in dose distribution between the boundary field and non-field was approximately ≥ 40%, which decreased exponentially as the distance from the boundary field increased. The gap dose distribution showed an average difference of approximately ≥ 47% compared with the beam profile central axis. This suggests the possibility of application as a radiotherapy digital dosimeter, as well as the possibility of analysing the dose distribution on the body surface.

Radiation-Hardened Cortex-R4F System-on-Chip Prototype With Total Ionizing Dose Dynamic Compensation in 28-nm FD-SOI

This article presents a radiation-hardened Cortex-R4F system-on-chip prototype with integrated total ionizing dose (TID) dynamic compensation capabilities, designed and fabricated in 28-nm fully depleted silicon-on-insulator (FD-SOI) technology. The processor was made robust to single-event effects, thanks to several design techniques: error correcting code (ECC) protected and bit-interleaved memories, optimized radiation-hardened sequential cells, and sensitive logic cells filtering. To counter the TID effects on the processor functionality and performances, the system embeds an integrated digital dosimeter. The dosimeter is capable of computing the TID in real time and providing the information to the system. Using a software lookup table (LUT), coupled with 28-nm FD-SOI technology support of asymmetric and wide-body-biasing, the reported TID can be converted to a request made to an external body-bias generator and be fully compensated. The system, operating at 0.9 V and 500 MHz, was tested under space grade radiations and has shown no failure in the 0 krad(Si) to 50 krad(Si) TID range.

Validation of a Dose Assessment Method to be Used in 18F FDG Loose Contamination Exercises.

Radiological emergency response may require responders to operate in contaminated environments. To provide more realistic training to these individuals, it has been proposed to disperse low amounts of short-lived radioactive material in simulated emergency scenarios. To demonstrate the applicability and safety of such activities, a limited exercise was conducted where 18F was sprayed in a small area and survey activities were executed. A pre-job external radiation exposure dose assessment was performed in preparation for this training. The research presented here compares participant external recorded doses to assessment results in order to validate the dose estimates. Two individuals were used during the dispersion, search, and survey activities. First, a radiation worker mixed 200 MBq Fludeoxyglucose 18F with 470 mL H2O in a weed sprayer and distributed it over a 3 m × 3 m area. After evaporation, an exercise participant performed search and survey activities in the area. Actual whole-body doses measured with optically stimulated luminescence dosimeters were 10 ± 1 μSv for both personnel. Whole-body digital dosimeters read 4.3 ± 0.2 μSv and 3.3 ± 0.5 μSv for the radiation worker and exercise participant, respectively. Actual extremity doses were below the dosimeters' minimum detectable limits for the radiation worker (thermoluminescence dosimeter) and exercise participant (optically stimulated luminescence dosimeter). The dose assessment-predicted whole-body doses were 2.8 ± 0.4 μSv and 3.2 ± 0.1 μSv for the radiation worker and exercise participant, respectively. The estimated dose to the radiation worker's hand was 21.8 ± 3.8 μSv, and the estimated dose to the exercise participant's knee was 13.4 ± 0.6 μSv. The study provided substantial evidence for the validity of the dose assessment method, supporting its use for a larger training exercise.

Evaluation of the Attenuation Rate for Clinical Application of a Flexible Skin Dosimeter in Radiotherapy

During radiotherapy, some patients owing to the variability in skin sensitivities, may experience adverse skin reactions for doses at which other patients are asymptomatic. Hence, when abnormal symptoms appear on a patient’s skin, the etiology should be verified. Accordingly, a surface dosimeter on the skin can help ascertain whether accurate doses are irradiated. Furthermore, surface doses are measured in the field junction gaps during craniospinal irradiation or during large-area radiotherapy to avoid adverse reactions due to cumulative skin doses from multiple beams. However, the point dose measurement errors of surface dosimeters exceed approximately 10% and have low-positional accuracies because the attachment sites are approximated with the help of the naked eye. Moreover, accurate information on field junction gaps cannot be obtained. Therefore, in clinical practice, a flexible array dosimeter is required as it can measure the dose distribution on the body surface by adapting its shape to the body curvatures. In this study, we implemented a flexible array dosimeter and, based on its constituent materials, evaluated the attenuation rate associated with its use. A polyester (PET) film was used as the underlying substrate. HgI2 and PbI2 photoconductors were used for their good performances in films. Furthermore, the measurement accuracy was verified through comparisons with Monte Carlo simulation outcomes. The resulting PET film had an attenuation rate of 2.22% at a 50-µm thickness. At the minimum material thickness of 25 µm, the attenuation rates for HgI2 and PbI2 were 4.69% and 5.72%, respectively. Further research is needed to fabricate HgI2-based digital skin dosimeters with a thickness under 25 µm. Radiation detection and pixel resolution should be evaluated to accurately confirm the field junction gap.

Evaluation of X-ray table mattresses for radiation attenuation and impact on image quality

IntroductionMattresses in the radiology department tend to be an overlooked aspect of imaging equipment. This paper evaluates the radiation attenuation characteristics of mattresses and the effect they have on image quality. MethodsThirteen mattresses (from new to 20 years of age) were evaluated. Incident air kerma (IAK) was measured in two conditions, with and without mattress over a range of exposure factors using a digital dosimeter. Image quality was assessed by calculating the inverse image quality factor (IQFinv) using a commercially available phantom (CDRAD) for the same exposure factors. The correlation of age and attenuation and image quality was calculated. ResultsMeasured IAK and image quality was affected by the addition of a mattress with older mattresses having greater attenuation; there is a moderate/large correlation (0.38–0.51) between age and IAK. IQFinv deteriorated with the addition of a mattress but there was no correlation with age (−0.41 to 0.16). Clinically, there is no impact of any mattress in the study as changes to the exposure factors to account for the attenuation are smaller than the increments in mAs available on X-ray equipment. ConclusionThe results indicate that while the presence of a mattress does impact on transmitted radiation and the quality of the image, the clinical impact is insignificant. Attenuation correlates with age but with no clinical significance. There is no correlation between age and image quality. Implications for practiceQuality control tests for attenuation and impact on image quality are not required in clinical practice. The method could be used by manufacturers to test new materials and mattresses and could provide users with specifications of new products.

On-Chip Total Ionizing Dose Digital Monitor in Fully Depleted SOI Technologies

This article presents a digital dosimeter for on-chip total ionizing dose (TID) computation, designed and fabricated in 28- and 22-nm fully depleted silicon-on-insulator (FD-SOI) technologies. FD-SOI has improved, by far, the robustness to single event effect (SEE), while TID may require fine control in high krad regime, leading to the interest for an integrated dynamic monitoring capability. The digital dosimeter is therefore implemented with a simplified TID hardware model and monitoring structure, capable of tracking and reporting TID value while being quasi-insensitive to voltage and temperature variations. The dosimeter is experimentally validated with gamma rays, showing less than 5% mismatch in dose estimate in the 0 to 50-krad(Si) range. Low-energy photons and alpha particles were used to extend the measurements to other sources and up to 500 krad(Si), where the mismatch with the theoretical estimate remains limited to 16%. The digital dosimeter, with an area of 0.002 mm2 and a very low imprint, is a suitable companion for any system requiring dynamic TID monitoring.

IMPLEMENTATION X-RAY RADIATION SAFETY MANAGEMENT IN RADIOLOGY LABORATORY OF ‘AISYIYAH YOGYAKARTA UNIVERSITY

Background: D3 Radiology Study Program is part of the new study programs at the Faculty of Health Sciences ‘Aisyiyah Yogyakarta University, which has accepted new students since 2016. In the learning process in the laboratory role is very important to support the success of the applied curriculum. So that the radiation safety management system is required in managing the laboratory, because radiation safety management is important for laboratory users, namely lecturers, assistant lecturers, and students. The purpose of this study was to analyze the implementation of X-ray radiation safety management at the Radiology Laboratory ‘Aisyiyah Yogyakarta University. Methods: This study uses descriptive qualitative research with data collection methods conducted in-depth interviews and observations. The sampling technique used was total sampling to all radiation workers as many as 12 people. Data analysis is done by reducing data, creating categorization tables and making, open coding so conclusions can be made. While presenting data in the form of quotations. Results: The results show that in the Radiology laboratory Aisyiyah YogyakartaUniversity already has a radiation protection organizational structure component consisting of an installation employer, radiation protection officers and radiation workers (8 lecturers and 4 Lecturer assistants). Health monitoring of radiation workers has been carried out during the process of submitting x-ray equipment permits. Radiology Laboratory of University 'Aisyiyah has sufficient radiation protection equipment. As for quality assurance, equipment they have quite complete. Suitability tests for radiographic equipment have been conducted during the process of permitting equipment, during learning and training for all lecturers and teaching assistants in 2016 and 2018. Monitoring individual doses are carried out using TLD, pen dosimeter, digital dosimeter. Conclusion: Document retention has been carried out but has not been well organized. While the education and training documents are still kept by each radiation worker on his personal documents.

Radiation Burden of Patient Obesity During Percutaneous Coronary Intervention

Introduction: Radiation dose to patients and staff during percutaneous coronary intervention (PCI) is relatively high and increased radiation exposure is associated with adverse health outcomes. This study sought to investigate the impact of patient body mass index (BMI) on radiation dose to the patient and primary operator during PCI procedures. Methods: In a single tertiary institute, operators wore real time digital dosimeters (RTDD) to measure radiation dose during 1662 PCI procedures over a 30-month period. The radiation dose absorbed by the RTDD was recorded at the end of each procedure. BMI was recorded and categorised as per the World Health Organization (WHO) classification and radiation dose to the patient was recorded as kerma area product (KAP). Radiation doses were grouped by BMI classification. Results: Boxplots in Figure 1, Figure 2 demonstrate how KAP (Gycm2) and RTDD (μSv) significantly increase (p < 0.001 and p < 0.001 respectively) as BMI increases.Figure 2View Large Image Figure ViewerDownload Hi-res image Download (PPT) Conclusions: Both KAP and RTDD increase with an increase in BMI. Both KAP and RTDD are more than three times higher when performing PCI procedures on obesity class III patients when compared normal weight patients. Greater radiation awareness is advised when treating obese patients.

Radioiodine (131I) therapies performed in a paediatric hospital: facilities and procedures

Radioiodine (131I) therapies on younger children with thyroid cancer and neuroblastoma can be challenging as they are required to be isolated for a period of time due to radiation safety concerns. At our hospital these therapies are performed in a purpose-built child-friendly therapy room. Nursing staff are able to provide personal care during the isolation period with minimum radiation exposure. Patients are provided with various age-appropriate entertainment items such as iPad, X-Box, DVD, craft and books to keep them entertained while in isolation. Parents can communicate freely with their child via the audio-visual system located in the Ward Parent Lounge and can also stay in the shielded part of the ante room of the therapy room. Nursing staff can communicate with the patient via a similar audio-visual system located in the nurses station so that they only need to enter the therapy room when they are required to provide personal patient care. All persons entering the therapy room are monitored with personal digital dosimeters. Patients accept the isolation period with minimal aggravation and the personal radiation exposures to staff, parents and visitors are well below the general public annual limit of 1000µSv. The design and facilities of the therapy room with its child-friendly surroundings and support network makes the experience of the isolation period easier and positive for both patients and parents. For Graves' disease, the patients are treated as outpatients in the Department of Nuclear Medicine and are discharged within a short time after the radioiodine administration.

Radiation exposure to the surgeon during minimally invasive spine procedures is directly estimated by patient dose.

Radiation exposure is a necessary component of minimally invasive spine procedures to augment limited visualization of anatomy. The surgeon's exposure to ionizing radiation is not easily recognizable without a digital dosimeter-something few surgeons have access to. The aim of this study was to identify an easy alternative method that uses the available radiation dose data from the C-arm to accurately predict physician exposure. The senior surgeon wore a digital dosimeter during all minimally invasive spine fusion procedures performed over a 12-month period. Patient demographics, procedure information, and radiation exposure throughout the procedure were recorded. Fifty-five minimally invasive spine fusions utilizing 330 percutaneous screws were included. Average radiation dose was 0.46 Rad/screw to the patient. Average radiation exposure to the surgeon was 1.06 ± 0.71μSv/screw, with a strong positive correlation (r = 0.77) to patient dose. The coefficient of determination (r2) was 0.5928, meaning almost two-thirds of the variability in radiation exposure to the surgeon is explained by radiation exposure to the patient. Intra-operative radiation exposure to the patient, which is easily identifiable as a continuously updated fluoroscopic monitor, is a reliable predictor of radiation exposure to the surgeon during percutaneous screw placement in minimally invasive spinal fusion surgery and therefore can provide an estimate of exposure without the use of a dosimeter. With this, a surgeon can better understand the magnitude of their exposure on a case-by-case basis rather than on a quarterly basis, or more likely, not at all. These slides can be retrieved under Electronic Supplementary Material.

A Wearable Colorimetric Dosimeter to Monitor Sunlight Exposure.

The personal ultraviolet (UV) dosimeter is a useful measurement tool to prevent UV induced dermal damages; however, conventional digital dosimeters are either bulky or require external power sources. Here, a wearable, colorimetric UV film dosimeter that provides color transition, from purple to transparent, is reported to indicate the UV dose. The film dosimeter is made of a purple photodegradable dye ((2Z,6Z)-2,6-bis(2-(2,6-diphenyl-4H-thiopyran-4-ylidene)ethylidene)cyclohexanone or DTEC) blended in low density polyethylene film. The DTEC film discolored 3.3 times more under the exposure of UV light (302 nm) than visible light (543 nm), and a UV bandpass filter is developed to increase this selectivity to UV light. The DTEC film completely discolors to transparency in 2 h under an AM 1.5 solar simulator, suggesting the potential as an indicator for individuals with types I-VI skin to predict interventions to avoid sunburn. Finally, the DTEC film is integrated with the UV bandpass filter on a wristband to function as a wearable dosimeter for low cost and convenient monitoring of sunlight exposure.

Right lateral versus left lateral view for forearm coronary angiography. An operator radiation exposure and image quality study

Objectives. The aim of this study was to analyze the operator radiation exposure (ORE) and the image quality in a coronary angiography (CA) of the standard left lateral view (LLV) and compare it with an alternative right lateral view (RLV). Background. Interventional cardiologists are exposed to high doses of scatter radiation, especially in angulated projections. Methods. We prospectively included consecutive patients who underwent diagnostic CA. A standard +90° LLV and an alternative RLV (−90°) were done in each patient with the same protocol. The operator effective dose rate (mSv/h) was determined for each projection with digital dosimeters located in the collar, waist and knee. The image quality of both the LLV and RLV was analyzed and compared to a standard projection. Results. 116 patients were enrolled; left coronary artery (LCA) was assessed in 52 patients and right coronary artery (RCA) in 64 patients. The ORE was significantly lower with the RLV compared to the conventional LLV with a maximum ORE reduction of 91.5% in the operator waist (LLV: 6.84 mSv h−1 versus RLV: 0.58 mSv h−1, p < 0.001). No significant differences in image quality were observed for the RCA in both projections. For the LCA, a slight loss of quality was observed with the RLV. Conclusions. −90° RLV is associated with a significant decrease in ORE compared to the conventional +90° LLV without losing image resolution for the RCA and resulting in a slight quality loss for the LCA evaluation. The RLV should be the first choice for RCA evaluation. For the LCA, the RLV loss of resolution should be balanced with the benefit of minimizing ORE, mainly in cases with long fluoroscopy times, such as complex percutaneous coronary interventional procedures.

Analysis of effective and organ dose estimation in CT when using mA modulation: A single scanner pilot study

IntroductionEffective dose (ED) estimation in CT examinations can be obtained by combining dose length product (DLP) with published ED per DLP coefficients or performed using software. These methods do not account for tube current (mA) modulation which is influenced by patient size. The aim of the work was to compare different methods of organ and ED estimation to measured values when using mA modulation in CT chest, abdomen and pelvis examinations. MethodOrgan doses from CT of the chest, abdomen and pelvis were measured using digital dosimeters and a dosimetry phantom. ED was calculated. Six methods of estimating ED accounting for mA modulation were performed using ImPACT CTDosimetry and Dose Length Product to ED coefficients. Corrections for the phantom mass were applied resulting in 12 estimation methods. Estimated organ doses from ImPACT CTDosimtery were compared to measured values. ResultsCalculated EDs were; chest 12.35 mSv (±1.48 mSv); abdomen 8.74 mSv (±1.36 mSv) and pelvis 4.68 mSv (±0.75 mSv). There was over estimation in all three anatomical regions. Correcting for phantom mass improved agreement between measured and estimated ED. Organ doses showed overestimation of dose inside the scan range and underestimation outside the scan range. ConclusionReasonable estimation of effective dose for CT of the chest and abdomen can be obtained using ImPACT CTDosimetry software or k-coefficients. Further work is required to improve the accuracy of ED estimation from CT of the pelvis. Accuracy of organ dose estimation has been shown to depend on the inclusion or exclusion of the organ from the scan range.

AUTOIMMUNE THYROIDITIS AMONG IONIZING RADIATION EXPOSED WORKERS IN CARDIAC CATHETERIZATION UNITS.

Introduction: It is well known that ionizing radiation (IR) exposure increases the risk of thyroid cancer; however less is known about its role in development of autoimmune thyroiditis. Aim of work: to investigate the thyroid gland functions,level of anti TPO among interventional cardiology team members searching for an association between the level of their occupational exposure to ionizing radiation and the thyroid gland integrity. Materials and methods: This work was carried out in Cardiac Catheterization Unit in National Heart Institute Center. The study comprised two groups, an exposed group of 47 cardiac catheterization workers (19 physicians, 15 nurses and 13 technicians) and a control group of 47 workers matched with the exposed group as regards age and sex. The studied groups were subjected to a detailed questionnaire, full clinical examinations. laboratory investigations in the form of serum thyroid stimulating hormone (TSH), Triiodothyronine (T3), Thyroxine (T4) and antithyroxiperoxidase antibodies (anti-TPO). Radiation exposure was monitored by digital dosimeter. Results: Dosimeter readings were higher among physicians followed by nurses and technicians. Statistically significant higher level of serum TSH, anti-TPO along with statistically significant lower levels of T3, were found among the exposed compared to control groups (P<0.05). Significant positive correlation was detectedbetween the level of anti-TPO and TSH (r= 0.876 P<0.001). Moreover, a significant negative correlation was found between anti-TPO and each of T3 (r= -0.814 P<0.001) and T4 (r= -0.324 P<0.05). ANOVA and Post Hoc tests showed significantly higher level of anti-TPO with significantly lower levels of T3 among the physicians compared to control group. Conclusion: Autoimmune thyroiditis may be considered as one of the adverse health hazards of occupational exposure to ionizing radiation in cardiac catheterization units. Recommendations: We recommend the regular measurement of thyroid hormone especially TSH and anti-TPO to detect early affection of thyroid glandamong radiation exposed workers.

SUGGESTED DIAGNOSTIC REFERENCE LEVELS FOR MAMMOGRAPHY X‑RAY EXAMINATION IN ETHIOPIA

&lt;p&gt;&lt;strong&gt;BACKGROUND:&lt;/strong&gt; A diagnostic reference levels (DRLs) form an efficient, concise, and powerful standard for optimizing the radiation protection of a patient. OBJECTIVES: To establish the first Ethiopian mammography diagnostic reference level (DRL) as a part of ongoing dose reduction program. &lt;strong&gt;MATERIALS AND METHODS:&lt;/strong&gt; A cross‑sectional study was conducted on breast patients having compressed breast thickness (CBT) between 3.7 cm to 5.3 cm in Addis Ababa, Ethiopia. Five mammographic units and 755 mammograms were included in the study period. The mean glandular dose (MGD) was assessed for standard size breast substituted by different polymethyl methacrylate (PMMA) phantoms and imaged under typical clinical conditions in two mammography units. Peak kilo voltage (kVp) and entrance surface air kerma (ESAK) were measured using calibrated digital dosimeter Mult‑O‑Meter Unfors, model 535L, Sweden. The data were analyzed statistically. &lt;strong&gt;RESULT:&lt;/strong&gt; The 3rd quartile value of all mammography units and that of private mammography units were found to be 2.37 and 1.73 milligray (mGy), respectively. Hospitals 3rd quartile values of MGD ranges between 1.57 to 7.21 mGy. The MDG based on 4.0 cm polymethyl methacrylate (PMMA) measurements was found to be 1.5 mGy. &lt;strong&gt;CONCLUSION:&lt;/strong&gt; Both phantom and patient dose values indicated unnecessary high doses in one government mammography unit. For this mammography unit, urgent dose‑reduction measures and follow‑up actions were recommended. &lt;/p&gt;