Results of extremity dosimetry based on the measurements at laboratory of individual and environmental dosimetry at IFJ PAN.

Laboratory of Individual and Environmental Dosimetry (LADIS) at the Institute of Nuclear Physics is the largest dosimetry service in Poland. Extremity ring dosimetry measurements are performed at LADIS laboratory for ˃20 years, with accredited procedure since 2002. According to the quality system based on PN-EN ISO/IEC 17025:2018-02 standard, Hp(0.07) personal dose equivalent is measured over the range of doses from 0.1 mSv to 1 Sv. Years of experience allow the laboratory to analyse the levels of doses received by workers in medical and industrial institutions cooperating with LADIS laboratory. Yearly, ˃30 000 of extremity measurements have been performed for about 1000 institutions in Poland on the quarterly basis. According to the internal classification, the radiation workers under radiation protection control have been divided into a few groups. The analysis indicated that most of the doses received by exposed workers were on the level of the natural radiation background, but some of them exceeded the dose limit. The results show that ˃60% of Hp(0.07) doses were below 0.1 mSv/quarter; however, some very high doses were also registered. The highest number of doses above 125 mSv was observed in nuclear medicine and interventional radiology. The percentage of overdoses was relatively small but looking at individual cases the risk of unexpected irradiation was noticeable. Therefore, constant monitoring is always necessary.

[Factors affecting exposure level for medical staff during orthopedic procedures under fluoroscopic control]. / Czynniki wplywajace na poziom narazenia personelu medycznego podczas zabiegów ortopedycznych pod kontrola fluoroskopii.

BACKGROUND: Extended control of staff exposure in interventional radiology has been legally required over the last few years. This is determined by a number of factors, including the type of procedure, technical conditions and methodology. In orthopedic procedures fluoroscopy is used to control surgical reconstructions. An influence of particular factors on the registered values of doses received by the members of medical team performing osteosynthesis for limb fractures is presented in this paper. MATERIAL AND METHODS: Doses received by individual interventional team members performing specific functions, operator, assisting physicians and scrub nurse, during a series of the procedures were measured. Each person was equipped with 4 dosimetric tools, containing thermoluminescent dosimeters, to measure the equivalent doses for the eyes, hand skin and the neck (outside the shield) and to evaluate effective doses. The investigations were performed in operational theatres of 3 hospitals in Lódz. RESULTS: The equivalent doses per one procedure for the eyes and hand skin of the operator were 0.029-0.073 mSv and 0.366-1.604 mSv, respectively. Significantly higher doses were noted during the procedures of intramedullary osteosynthesis, especially for the operator. An average age and body mass index (BMI) of patients treated in the monitored hospitals did not differ statistically. CONCLUSIONS: Based on the dosimetric measurements the following conclusions can be drawn: in orthopedic procedures of interventional radiology (IR) the exposure of the staff is mostly determined by the type of procedure and more precisely by its complexity and by the optimized use of X-ray unit, including pulsed fluoroscopy. It is also revealed that the operator is the most exposed person in the interventional team. Med Pr 2017;68(1):75-83.

[Occupational exposure in orthopedic procedures under fluoroscopic control]. / Narazenie zawodowe podczas procedur ortopedycznych wykonywanych pod kontrola fluoroskopii rentgenowskiej.

BACKGROUND: In interventional radiology the highest radiation doses are usually recorded for both the medical staff and the patients. Interventional procedures with X-rays are implemented in a number of medical specializations. This paper concerns the exposure of interventional teams performing orthopedic procedures under X-rays control. MATERIAL AND METHODS: Doses for interventional teams were measured in the 3 Lódz hospitals. Thermoluminescent dosemeters were applied to measure the following dose equivalents: Hp(3) for eye lens, Hp(0.07) for palm skin, Hp(10) at the level of the neck without a protective shield (i.e., collar) and Hp(10) for the whole body on the front surface of the trunk (measured under the protective apron at the level of the chest). RESULTS: Doses for the operator who performs surgery, assisting physicians and scrub nurse were measured during 95 procedures. The highest doses were received by the operator the dose for eyes per 1 procedure did not exceed 0.1 mSv, the highest dose for hands was 1.6 mSv and the highest recorded effective dose was 0.02 mSv. CONCLUSIONS: On the basis of the results of measurements and their comparison with the values reported in the literature it may be concluded that the obtained results fall within the published reference range (for non-vascular procedures). This proves the compatibility of practice in the monitored Lódz hospitals with routine methodology applied in other interventional departments. The measurement results confirm that the usage of thermoluminescent dosimetry is fully adequate for the evaluation of exposure in interventional radiology and that the usage of at least 2 dosemeters for that staff is necessary. Med Pr 2017;68(2):221-227.

HOW DO HOSPITAL STERILISATION PROCEDURES AFFECT THE RESPONSE OF PERSONAL EXTREMITY RINGS AND OF EYE LENS TL DOSEMETERS?

Stringent standards of hygiene must be applied in medical institutions, especially at operating blocks or during interventional radiology procedures. Medical equipment, including personal dosemeters that have to be worn by medical staff during such procedures, needs therefore to be sterilised. In this study, the effect of various sterilisation procedures has been tested on the dose response of extremity rings and of eye lens dosemeters in which thermoluminescent (TL) detectors (of types MTS-N and MCP-N, respectively) are used. The effects of medical sterilisation procedures were studied: by chemicals, by steam or by ultraviolet (UV), on the dose assessment by extremity rings and by eye lens dosemeters. Since it often happens that a dosemeter is accidentally machine-washed together with protective clothing, the effect of laundering on dose assessment by these dosemeters was also tested. The sterilisation by chemicals is mostly safe for TL detectors assuming that the dosemeters are waterproofed. Following sterilisation by water vapour, the response of these dosemeters diminished by some 30 %, irrespectively of the period of sterilisation; therefore, this method is not recommended. UV sterilisation can be applied to EYE-D™ eye lens dosemeters if their encapsulation is in black. The accidental dosemeter laundry in a washing machine has no impact on measured dose.

Dose levels of the occupational radiation exposures in Poland based on results from the accredited dosimetry service at the IFJ PAN, Krakow.

Individual dosimetry service based on thermoluminescence (TLD) detectors has started its activity at the Institute of Nuclear Physics (IFJ) in Krakow in 1965. In 2002, the new Laboratory of Individual and Environment Dosimetry (Polish acronym LADIS) was established and underwent the accreditation according to the EN-PN-ISO/IEC 17025 standard. Nowadays, the service is based on the worldwide known standard thermoluminescent detectors MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P), developed at IFJ, processed in automatic thermoluminescent DOSACUS or RE2000 (Rados Oy, Finland) readers. Laboratory provides individual monitoring in terms of personal dose equivalent H(p)(10) and H(p)(0.07) in photon and neutron fields, over the range from 0.1 mSv to 1 Sv, and environmental dosimetry in terms of air kerma K(a) over the range from 30 µGy to 1 Gy and also ambient dose equivalent H*(10) over the range from 30 µSv to 1 Sv. Dosimetric service is currently performed for ca. 3200 institutions from Poland and abroad, monitored on quarterly and monthly basis. The goal of this paper is to identify the main activities leading to the highest radiation exposures in Poland. The paper presents the results of statistical evaluation of ∼ 100,000 quarterly H(p)(10) and K(a) measurements performed between 2002 and 2009. Sixty-five per cent up to 90 % of all individual doses in Poland are on the level of natural radiation background. The dose levels between 0.1 and 5 mSv per quarter are the most frequent in nuclear medicine, veterinary and industrial radiography sectors.

Modeling the response of thermoluminescence detectors exposed to low- and high-LET radiation fields.

Lithium fluoride thermoluminescence (TL) detectors, with different Li composition (Li-6 and Li-7) and various activators (LiF:Mg,Ti, LiF:Mg,Cu,P), are widely used for dosimetry in space. The primary radiation field in space is composed of fast electrons, protons and heavy charged particles (HCP). By its interaction with the structures of the spacecraft, this field may be modified inside the crew cabin. Therefore, calibration of TL detectors against a dose of gamma-rays is not sufficient for relating the TL readout to absorbed dose or to quantities relevant in radiation protection, without suitable correction. We introduce and calculate the detection efficiency, eta, relative to gamma-ray dose, of lithium fluoride detectors after proton and heavy charged particle (HCP) irradiation. We calculate eta for MCP-N (LiF:Mg,Cu,P) and for MTS-N (LiF:Mg,Ti) using microdosimetric models. The microdosimetric distributions used in these models (for HCP of charges between Z=1 to Z=8 and in the energy range between 0.3 MeV/amu and 20 MeV/amu) are calculated using an analytical model, based on the results of Monte Carlo simulated charged particle tracks using the MOCA-14 code. The ratio etaMCP-N/etaMTS-N for protons of stopping power (in water) below 10 keV/microm lies in the range between 0.65 and 1.0 and for HCP with Z>1--between 0.3 and 0.6. The stopping power of the particle is found not to be a unique parameter to scale the response of TL detectors. The combination of response of LiF:Mg,Cu,P and LiF:Mg,Cu,P detectors can be more suitable for a dose correction in space radiation fields.