Analysis of dose distribution around a computed tomography scanner in terms of exposure to scattered ionizing radiation of caregivers of pediatric patients.

OBJECTIVES: During computed tomography (CT), a large amount of ionizing radiation is emitted to ensure high quality of the obtained radiological image. This study measured the dose distribution around the CT scanner and the exposure of people staying near the CT scanner during the examination. MATERIAL AND METHODS: The measurements used an anthropomorphic phantom to assess human exposure to ionizing radiation. The probability of inducing leukemia and other cancers as a result of absorbing doses recorded around the CT device was also calculated. RESULTS: The highest exposure to scattered radiation in the proximity of the CT scanner is recorded at the gantry of the tomograph, i.e., 55.7 µGy, and the lowest, below lower detection limit of 6 µGy at the end of the diagnostic table. The whole-body detector placed on the anthropomorphic phantom located at the diagnostic table right next to the CT gantry recorded 59.5 µSv and at the end of the table 1.5 µSv. The average doses to the lenses in these locations were: 32.1 µSv and 2.9 µSv, respectively. CONCLUSIONS: The probability of induction of leukemia or other types of cancer is low, but the need for people to stay in the examination room during a CT examination should be limited to the necessary minimum. Int J Occup Med Environ Health. 2024;37(3).

[Individual dosimetry as an element of health prevention for employees exposed to ionizing radiation]. / Dozymetria indywidualna jako element profilaktyki zdrowotnej pracowników narazonych na promieniowanie jonizujace.

The paper presents the current radiation protection standards, in line with the recommendations of the International Commission on Radiological Protection (ICRP), and their evolution over the years based on new knowledge about the biological effects of ionizing radiation and the changing attitude of people to the accepted risk. The work takes into account in particular the role of the dose limit principle and individual dose measurements in activities aimed at health prevention of individual people occupationally exposed to ionizing radiation. Med Pr Work Health Saf. 2023;74(6):527-39.

Effectiveness of staff radiation protection devices for interventional cardiology procedures.

PURPOSE: To evaluate the effectiveness of currently available radioprotective (RP) devices in reducing the dose to interventional cardiology staff, especially to the eye lens and brain. METHODS: The performances of five RP devices (masks, caps, patient drapes, staff lead and lead-free aprons and Zero-Gravity (ZG) suspended radiation protection system) were assessed by means of Monte Carlo (MC) simulations. A geometry representative of an interventional cardiology setup was modelled and several configurations, including beam projections and staff distance from the source, were investigated. In addition, measurements on phantoms were performed for masks and drapes. RESULTS: An average dose reduction of 65% and 25% to the eyes and the brain respectively was obtained for the masks by MC simulations but a strong influence of the design was observed. The cap effectiveness for the brain ranges on average between 13% and 37%. Nevertheless, it was shown that only some upper parts of the brain were protected. There was no significant difference between the effectiveness of lead and lead-free aprons. Of all the devices, the ZG system offered the highest protection to the brain and eye lens and a protection level comparable to the apron for the organs normally covered. CONCLUSION: All investigated devices showed potential for dose reduction to specific organs. However, for masks, caps and drapes, it strongly depends on the design, exposure conditions and staff position. Therefore, for a clinical use, it is recommended to evaluate their effectiveness in the planned conditions of use.

Ionizing radiation and volumetric mammographic density.

OBJECTIVES: Mammographic density (MD) refers to the percentage of dense tissue of an entire breast and was proposed to be used as a surrogate marker for breast cancer. High-dose ionizing radiation (IR) has been recognized as a breast cancer risk factor. The aim of our study was to investigate association between lifetime low dose ionizing radiation (LDIR) and MD. MATERIAL AND METHODS: A cross-sectional study included 467 women aged 40-60 years who underwent screening mammography in Lódz, Poland. The digital mammography examination of the breasts included both craniocaudal and mediolateral oblique views. The volumetric breast density (VBD) (%) and fibrograndular tissue volume (FG) (cm3) were determined based on the analysis of mammographic image ("for processing") using Volpara Imaging Software. The exposure to IR was estimated for each individual, based on the data from interviews about diagnostic or therapeutic medical procedures performed in the area of the neck, chest, abdomen and spine, which involved X-rays and γ rays and the data about the doses derived from literature. Linear and logistic regression were fitted with VBD and FG as the outcomes and organ breast dose, effective dose and number of mammographies as the determinants, adjusted for major confounders. RESULTS: The analyses showed no association between VBD or FG and the breast organ dose or the effective dose. The only significant finding observed concerned the association between the number of mammographies and the FG volume with ß coefficient: 0.028 (95% CI: 0.012-0.043), and predicted mean FG volume >13.4 cm3 among the women with >3 mammographies when compared to those with none. CONCLUSIONS: This study does not, in general, provide support for the positive association between LDIR and MD. The weak association of the FG volume with the number of mammographies warrants further verification in larger independent studies. Int J Occup Med Environ Health. 2022;35(5):635-49.

The effect of lead free cap on the doses of ionizing radiation to the head of interventional cardiologists working in haemodynamic room.

OBJECTIVES: The study aim was to analyse the influence of the lead free cap on doses received by interventional cardiologists. The impact of lead free cap on doses to the head were evaluated in number of studies. As different methods used to assess the attenuation properties of protective cap can lead to ambiguous results, a detailed study was performed. MATERIAL AND METHODS: The effectiveness of a lead free cap in reducing the doses to the skin was assessed in clinic by performing measurements with thermoluminescent dosimeters attached inside and outside the cap first during individual coronary angiography (CA) or CA/percutaneous transluminal coronary angioplasty (CA/PTCA) procedures and then cumulated during few procedures of the same type. In order to investigate the effect of the cap on reducing the doses to the brain additional measurements were performed with a male Alderson Rando and polymethyl methacrylate (PMMA) phantoms representing the physician and the patient, respectively for different projections. The brain dose per procedure, annual and cumulated during entire working practice were estimated for both cases working with and without the cap. RESULTS: The dose reduction factor (RF) for the skin (the quotient of doses outside and inside the cap) vary from 1.1 up to 4.0 in clinical conditions; on average 2.3-fold reduction is observed in the most exposed left temple. The RFs determined for the part of the head covered by the cap range from 1.4 to 1.8 while for the brain from 1.0 to 1.1 depending on the projection. The estimated annual brain dose for interventional cardiologist performing yearly 550 CA/PTCA procedures without any protective shields is 7.2 mGy and it is reduced with the lead free cap by an average factor of 1.1. CONCLUSIONS: The study results proved the considerable effectiveness of lead free cap to protect the skin but very limited to protect the brain. Int J Occup Med Environ Health. 2022;35(5):549-60.

Occupational exposure to physicians working with a Zero-Gravity™ protection system in haemodynamic and electrophysiology labs and the assessment of its performance against a standard ceiling suspended shield.

A two centre clinical study was performed to analyse exposure levels of cardiac physicians performing electrophysiology and haemodynamic procedures with the use of state of the art Zero-Gravity™ radiation protective system (ZG). The effectiveness of ZG was compared against the commonly used ceiling suspended lead shield (CSS) in a haemodynamic lab. The operator's exposure was assessed using thermoluminescent dosimeters (TLDs) during both ablation (radiofrequency ablation (RFA) and cryoablation (CRYA)) and angiography and angioplasty procedures (CA/PCI). The dosimeters were placed in multiple body regions: near the left eye, on the left side of the neck, waist and chest, on both hands and ankles during each measurement performed with the use of ZG. In total 29 measurements were performed during 105 procedures. To compare the effectiveness of ZG against CSS an extra 80 measurements were performed with the standard lead apron, thyroid collar and ceiling suspended lead shield during CA/PCI procedures. For ZG, the upper values for the average eye lens and whole body doses per procedure were 4 µSv and 16 µSv for the left eye lens in electrophysiology lab (with additionally used CSS) and haemodynamic lab (without CSS), respectively, and about 10 µSv for the remaining body parts (neck, chest and waist) in both labs. The skin doses to hands and ankles non-protected by the ZG were 5 µSv for the most exposed left finger and left ankle in electrophysiology lab, while in haemodynamic lab 150 µSv and 17 µSv, respectively. The ZG performance was 3 times (p < 0.05) and at least 15 times (p < 0.05) higher for the eye lenses and thoracic region, respectively, compared to CSS (with dosimeters on the apron/collar). However, when only ZG was used slightly higher normalised doses were observed for the left finger compared to CSS (5.88e - 2 Sv/Gym2 vs. 4.31 e - 2 Sv/Gym2, p = 0.016). The study results indicate that ZG performance is superior to CSS. It can be simultaneously used with the ceiling suspended lead shield to ensure the protection to the hands as long as this is not obstructive for the work.

CORRELATION OF EYE LENS DOSES AND PERSONAL DOSE EQUIVALENT MEASURED ON THE ARM OF INTERVENTIONAL CARDIOLOGISTS FOR A RETROSPECTIVE ASSESSMENT OF DOSES TO OPERATORS' EYE LENS.

Coefficients converting the readings of the whole body dosemeter worn on the left arm to eye lens doses were determined by analysing the correlations between Hp(10) and Hp(3) values. Doses were measured on a phantom for specific C-arm projections typically used during CA/PCI procedures. In order to estimate the cumulative eye lens doses, conversion coefficients were then applied to the dose records of interventional cardiologists collected in the database of dosimetry service between the years 1995 and 2009. The Hp(10) to Hp(3) conversion coefficients are 0.29 (CV = 34%) and 0.17 (CV = 42%) for left and right eye lens, respectively. However, they can vary from one laboratory to another depending on working technique. From among 61 interventional cardiologists, none exceeded the threshold dose of 0.5 Gy for eye lens opacities. However, 44% of interventional cardiologists were likely to exceed the annual limit of 20 mSv for the most exposed eye at least once in the analysed time period.

Occupational exposure to ionizing radiation and lens opacity in interventional cardiologists.

OBJECTIVES: Interventional cardiologists (ICs) are occupationally exposed to low or moderate doses of ionizing radiation from repeated exposures. It is not clear whether these occupational conditions may affect their eye lens. Therefore, the risk of radiation-induced cataract in the cohort of Polish interventional cardiologists is analyzed in this paper. MATERIAL AND METHODS: The study group consisted of 69 interventional cardiologists and 78 control individuals occupationally unexposed to ionizing radiation. The eye lens opacities were examined using a slit camera and evaluated with Lens Opacities Grading System III. Cumulative eye lens doses were estimated retrospectively using a questionnaire including data on occupational history. RESULTS: The average cumulative dose to the left and right eye lens of the ICs was 224 mSv and 85 mSv, respectively. Nuclear opalescence and nuclear color opacities in the most exposed left eye were found in 38% of the ICS for both types, and in 47% and 42% of the controls, respectively. Cortical opacities were found in 25% of the ICS and 29% of the controls. Posterior subcapsular opacities were rare: about 7% in the ICs group and 6% in the control group. Overall, there was some, but statistically insignificant, increase in the risk for opacity in the ICs group, relative to the control group, after adjusting for the subjects' age, gender, smoking status and medical exposure (adjusted OR = 1.47, 95% CI: 0.62-3.59 for the pooled "any-eye any-type" opacity). There was also no evidence for an increased opacity risk with an increase in the dose. CONCLUSIONS: The study found no statistically significant evidence against the hypothesis that the risk of cataract in the group of the ICs occupationally exposed to low doses of ionizing radiation is the same as in the control group. Nevertheless, the adverse effect of ionizing radiation still cannot be excluded due to a relatively small study sample size. Int J Occup Med Environ Health. 2019;32(5):663-75.

Effect of the radiation protective apron on the response of active and passive personal dosemeters used in interventional radiology and cardiology.

In fluoroscopy guided interventional procedures, workers use protective garments and often two personal dosemeters, the readings of which are used for the estimation of the effective dose; whereas the dosemeter above the protection can be used for the estimation of the equivalent dose of the lens of the eye. When a protective apron is worn the scattered field that reaches the dosemeter is different from the case where no protection is used; this study analyses the changes in the response of seven passive and eight active personal dosemeters (APDs) when they are placed above a lead or lead equivalent garment for S-Cs and x-ray diagnostic qualities. Monte Carlo simulations are used to support the experimental results. It is found that for passive dosemeters, the influence on the dosemeter's response to the lead or lead equivalent was within the range 15%-38% for the x-ray qualities. This effect is smaller, of the order of 10%, when lead-free garments are used, and much smaller, within 1%-10%, for most of the APDs used in the study. From these results it is concluded that when comparing passive and active dosemeter measurements worn above the protection, a difference of 20%-40% is expected. The effect is small when deriving the effective dose from double dosimetry algorithms, but it can be of major importance when eye lens monitoring is based on the use of the dosemeter worn above the protection.

Past and present work practices of European interventional cardiologists in the context of radiation protection of the eye lens-results of the EURALOC study.

This paper investigates over five decades of work practices in interventional cardiology, with an emphasis on radiation protection. The analysis is based on data from more than 400 cardiologists from various European countries recruited for a EURALOC study and collected in the period from 2014 to 2016. Information on the types of procedures performed and their annual mean number, fluoroscopy time, access site choice, x-ray units and radiation protection means used was collected using an occupational questionnaire. Based on the specific European data, changes in each parameter have been analysed over decades, while country-specific data analysis has allowed us to determine the differences in local practices. In particular, based on the collected data, the typical workload of a European cardiologist working in a haemodynamic room and an electrophysiology room was specified for various types of procedures. The results showed that when working in a haemodynamic room, a transparent ceiling-suspended lead shield or lead glasses are necessary in order to remain below the recommended eye lens dose limit of 20 mSv. Moreover, the analysis revealed that new, more complex cardiac procedures such as chronic total occlusion, valvuloplasty and pulmonary vein isolation for atrial fibrillation ablation might contribute substantially to annual doses, although they are relatively rarely performed. The results revealed that considerable progress has been made in the use of radiation protection tools. While their use in electrophysiology procedures is not generic, the situation in haemodynamic procedures is rather encouraging, as ceiling-suspended shields are used in 90% of cases, while the combination of ceiling shield and lead glasses is noted in more than 40% of the procedures. However, we find that still 7% of haemodynamic procedures are performed without any radiation protection tools.

Feasibility of setting up generic alert levels for maximum skin dose in fluoroscopically guided procedures.

PURPOSE: The feasibility of setting-up generic, hospital-independent dose alert levels to initiate vigilance on possible skin injuries in interventional procedures was studied for three high-dose procedures (chemoembolization (TACE) of the liver, neuro-embolization (NE) and percutaneous coronary intervention (PCI)) in 9 European countries. METHODS: Gafchromic® films and thermoluminescent dosimeters (TLD) were used to determine the Maximum Skin Dose (MSD). Correlation of the online dose indicators (fluoroscopy time, kerma- or dose-area product (KAP or DAP) and cumulative air kerma at interventional reference point (Ka,r)) with MSD was evaluated and used to establish the alert levels corresponding to a MSD of 2 Gy and 5 Gy. The uncertainties of alert levels in terms of DAP and Ka,r, and uncertainty of MSD were calculated. RESULTS: About 20-30% of all MSD values exceeded 2 Gy while only 2-6% exceeded 5 Gy. The correlations suggest that both DAP and Ka,r can be used as a dose indicator for alert levels (Pearson correlation coefficient p mostly >0.8), while fluoroscopy time is not suitable (p mostly <0.6). Generic alert levels based on DAP (Gy cm2) were suggested for MSD of both 2 Gy and 5 Gy (for 5 Gy: TACE 750, PCI 250 and NE 400). The suggested levels are close to the lowest values published in several other studies. The uncertainty of the MSD was estimated to be around 10-15% and of hospital-specific skin dose alert levels about 20-30% (with coverage factor k = 1). CONCLUSIONS: The generic alert levels are feasible for some cases but should be used with caution, only as the first approximation, while hospital-specific alert levels are preferred as the final approach.