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).

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.

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.

DETERMINING THE DOSE RATE DEPENDENCE OF DIFFERENT ACTIVE PERSONAL DOSEMETERS IN STANDARDIZED PULSED AND CONTINUOUS RADIATION FIELDS.

In 2016, the EURADOS working group 12 started a project to gather reliable data concerning the behavior of active personal dosemeters (APDs) used by European hospitals in standardized pulsed and hospital fields. This paper concentrates on the tests that deal with the dose rate dependence of APDs in laboratory tests. The dependence on the dose rate was determined for 10 dosemeter types with continuous radiation of a 60Co source and pulsed radiation of the reference radiation facility of Physikalisch-Technische Bundesanstalt. Furthermore, irradiations were done with continuous radiation of a 137Cs source of the Karlsruher Institute of Technology and with continuous X-rays of the two radiation qualites in radiation beams emerging from the X-ray source assembly, RQR5 and RQR8, of Nofer Institute of Occupational Medicine. For the first time, APDs have been systematically investigated under laboratory conditions in a pulsed reference fields according to ISO/TS 18090-1 and the experience gained by these test procedures will be included in the new IEC/TS 63050.

CALIBRATION OF LOW ENERGY X-RAY EXPERIMENTAL SETUP WITH STRONGLY FILTERED BEAM USING DATA FROM A SEMICONDUCTOR AND A THERMOLUMINESCENT DETECTORS.

The calibration of low energy X-ray experimental setup with strongly filtered beam dedicated to radiobiological research was performed using the absorbed dose calculated from the data collected by two types detectors. For this purpose a semiconductor (Amptek, USA) and a thermoluminescent (Institute of Nuclear Physics, Krakow, Poland) detectors were applied. The absorbed dose in water values estimated by both detectors are in good agreement.

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.

Combined effect of X-ray radiation and static magnetic fields on reactive oxygen species in rat lymphocytes in vitro.

The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X-ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X-ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it.

[Quality control testing of x-ray equipment used in medical diagnostic: results of interlaboratory comparison]. / Ocena pomiaru parametrów fizycznych w kontroli jakosci aparatury rentgenodiagnostycznej - wyniki miedzylaboratoryjnych badan porównawczych.

BACKGROUND: Effective diagnostic radiology system should be based on an efficient and suitable servicing of medical X-ray equipment. According to Polish requirements, all radiology departments are obligated to carry out quality control (QC) test of their X-ray set. In practice, testing is mostly performed by accredited external QC services, which have to participate in periodic interlaboratory comparison (ILC) to maintain or obtain the accreditation. Large-scale ILC for QC services were performed at the Nofer Institute of Occupational Medicine for three ranges of diagnostic radiology: dental, conventional and mammography. MATERIALS AND METHODS: During ILC, the metrological coherence of main physical parameters, which determine good quality of diagnostic image, were estimated and compared with appropriate reference values ensured by ILC organizer. The ILC participants comprised 29 QC services. The measurements were performed by ILC participants under laboratory conditions, using their own calibrated meters, according to routine procedures. All measurement results were assessed by calculating the E(n) value, normalized with respect to the uncertainties. RESULTS: Of the 328 evaluated results only 11 (3.4%) were classified as unsatisfactory. As much as 82% of them applied to mammography. Thus, the final evaluation revealed negative results in 2 of the 29 participants, which means that their satisfactory scores for the studied ranges were below 75%. CONCLUSIONS: In spite of predominant amount of satisfactory results, ILC indicated some regions of divergence e.g. large differences in evaluation of uncertainties and other inconsistencies.

[Dosimetric system for assessing doses received by people occupationally exposed to external sources of ionizing radiation]. / System wielkosci dozymetrycznych do oceny poziomu dawek otrzymywanych przez personel zawodowo narazony na zewnetrzne zródla promieniowania jonizujacego.

The current system of dosimetric quantities has been defined by the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU). Complexity of the system implies the physical nature of ionizing radiation, resulting from the presence of different types of radiation of different ionization capabilities, as well as the individual radiation sensitivity of biological material exposed. According to the latest recommendations, there are three types of dosimeter quantities relevant to radiation protection and radiological assessment of occupational exposure. These are the basic quantities, safety quantities and operational quantities. Dose limits for occupational exposure relate directly to the protection quantities, i.e. the equivalent dose and effective dose, while these quantities are practically unmeasurable in real measurement conditions. For this reason, in the system of dosimetric quantities directly measurable operating volumes were defined. They represent equivalents of the protection quantities that allow for a reliable assessment of equivalent and effective dose by conducting routine monitoring of occupational exposure. This paper presents the characteristics of these quantities, their relationships and importance in assessing individual effects of radiation. Also the methods for their implementation in personal and environmental dosimetry were showcased. The material contained in the article is a compendium of essential information about dosimetric quantities with reference to the contemporary requirements of the law, including the changed annual occupational exposure limit for the lens of the eye. The material is especially addressed to those responsible for dosimetry monitoring in the workplace, radiation protection inspectors and occupational health physicians.