Piotr Tulik

Characterisation of radiation field for irradiation of biological samples at nuclear reactor—comparison of twin detector and recombination methods

Central Laboratory for Radiological Protection is involved in achieving scientific project on biological dosimetry. The project includes irradiation of blood samples in radiation fields of nuclear reactor. A simple facility for irradiation of biological samples has been prepared at horizontal channel of the nuclear reactor MARIA in NCBJ in Poland. The radiation field, composed mainly of gamma radiation and thermal neutrons, has been characterised in terms of tissue kerma using twin-detector technique and recombination chambers.

Experimental investigation on radiation shielding of high performance concrete for nuclear and radiotherapy facilities

Abstract This paper presents the set of procedures developed in Radiation Protection Measurements Laboratory at National Centre for Nuclear Research for evaluation of shielding properties of high performance concrete. The purpose of such procedure is to characterize the material behaviour against gamma and neutron radiation. The range of the densities of the concrete specimens was from 2300 to 3900 kg/m3. The shielding properties against photons were evaluated using 137Cs and 60Co sources. The neutron radiation measurements have been performed by measuring the transmitted radiation from 239PuBe source. Scattered neutron radiation has been evaluated using the shadow cone technique. A set up of ionization chambers was used during all experiments. The gamma dose was measured using C-CO2 ionization chamber. The neutron dose was evaluated with recombination chamber of REM-2 type with appropriate recombination method applied. The method to distinguish gamma and neutron absorbed dose components in mixed radiation fields using twin detector method was presented. Also, recombination microdosimetric method was applied for the obtained results. Procedures to establish consecutive half value layers and tenth value layers (HVL and TVL) for gamma and neutron radiation were presented. Measured HVL and TVL values were linked with concrete density to highlight well known dependence. Also, influence of specific admixtures to concrete on neutron attenuation properties was studied. The results confirmed the feasibility of approach for the radiation shielding investigations.

MEASUREMENTS OF THE IONISING RADIATION LEVEL AT A NUCLEAR MEDICINE FACILITY PERFORMING PET/CT EXAMINATIONS.

This paper presents the results of radiation level measurements at workplaces in a nuclear medicine facility performing PET/CT examinations. This study meticulously determines the staff radiation exposure in a PET/CT facility by tracking the path of patient movement. The measurements of the instantaneous radiation exposure were performed using an electronic radiometer with a proportional counter that was equipped with the option of recording the results on line. The measurements allowed for visualisation of the staffs instantaneous exposure caused by a patient walking through the department after the administration of 18F-FDG. An estimation of low doses associated with each working step and the exposure during a routine day in the department was possible. The measurements were completed by determining the average radiation level using highly sensitive thermoluminescent detectors.

Low-level gamma and neutron monitoring based on use of proportional counter filled with 3He in polythene moderator: study of the responses to gamma and neutrons

It has been shown that a proportional counter filled with (3)He placed centrally inside a polythene sphere opens a new possibility for measuring gamma photons and neutrons in the separate pulse-height windows. The responses to gamma and neutrons (in terms of ambient dose equivalent) of the detector assembly consisting of 203-mm polythene sphere with centrally positioned 40-mm diameter (3)He proportional counter have been studied. The response to secondary gammas from capture process in hydrogen has also been studied. The rather preliminary studies indicate that the proposed measuring system has very promising features as an ambient dose equivalent device for mixed gamma-neutron fields.

Ambient dose equivalent measurements in secondary radiation fields at proton therapy facility CCB IFJ PAN in Krakow using recombination chambers

Abstract This work presents recombination methods used for secondary radiation measurements at the Facility for Proton Radiotherapy of Eye Cancer at the Institute for Nuclear Physics, IFJ, in Krakow (Poland). The measurements of H*(10) were performed, with REM-2 tissue equivalent chamber in two halls of cyclotrons AIC-144 and Proteus C-235 and in the corridors close to treatment rooms. The measurements were completed by determination of gamma radiation component, using a hydrogen-free recombination chamber. The results were compared with the measurements using rem meter types FHT 762 (WENDI-II) and NM2 FHT 192 gamma probe and with stationary dosimetric system.

INVESTIGATION OF SECONDARY MIXED RADIATION FIELD AROUND A MEDICAL LINEAR ACCELERATOR

The aim of this study is to investigate secondary mixed radiation field around linac, as the first part of an overall assessment of out-of-field contribution of neutron dose for new advanced radiation dose delivery techniques. All measurements were performed around Varian Clinic 2300 C/D accelerator at Maria Sklodowska-Curie Memorial, Cancer Center and Institute of Oncology, Krakow Branch. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination (as an estimate of quality factor Q), measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt. Estimation of Dt and Q4 allowed for the ambient dose equivalent H*(10) per monitor unit (MU) calculations. Measurements around linac were performed on the height of the middle of the linacs head (three positions) and on the height of the linacs isocentre (five positions). Estimation of secondary radiation level was carried out for seven different configurations of upper and lower jaws position and multileaf collimator set open or closed in each position. Study includes the use of two photon beam modes: 6 and 18 MV. Spatial distribution of ambient dose equivalent H*(10) per MU on the height of the linacs head and on the standard couch height for patients during the routine treatment, as well as relative contribution of gamma and neutron secondary radiation inside treatment room were evaluated.

X-ray and neutron radiography studies of archeological objects

The aim of the study was application and comparison of neutron (NR) and X-ray radiography (XR) in investigations of archeological and Culture Heritage (CH) objects. The investigation had interdisciplinary character based on physical and archaeological knowledge. The use of two complementary imagining techniques provided data about artefacts structure regarding their composition and shape diversity. The study concerned different objects of metal alloys, corrosion bulk form, ceramics and ancient bone remnants.

Characterization of low-LET radiation fields for irradiation of biological samples using recombination chamber

Irradiation of biological samples for biological dosimetry and radiobiological studies should be performed in well characterized radiation fields. The reference quantity for gamma and X-ray radiations is usually kerma in air, deter-mined with ionization chamber. The paper presents an example of characterization performed for X-rays using a thin-walled, reference ionization chamber. Standard procedure was completed with determination of Recombination Index of Radiation Quality (RIQ), determined with recombination chamber. Irradiations were performed at special stand supporting standard test tubes, which are commonly used in bio-logical dosimetry for blood samples. The influence of all elements of the supporting stand was carefully determined and taken into account in calculations of tissue kerma in blood. The RIQ values reflect microdosimetric parameters of the radiation. The measurements performed for unfiltered X-rays of different energies resulted in markedly higher values of RIQ, comparing to those measured for 137Cs or 60Co gamma radiation fields.

Passive multi-layer neutron spectrometer for neutron radiation dosimetry

Paper describes the method of neutron radiation dosimetry using polyethylene moderator and thermoluminescent detectors. Mechanisms of neutrons’ slowing down, detection and measurement steps using TLD are presented. The paper contains a description of the construction and the arrangements of the multi-moderator with possibility of placing passive detectors at different thicknesses in the sphere. Additionally, there is presented a possibility of ionization chamber utilization as an active part of the spectrometer. Results of geometrical modelling and Monte Carlo simulations are presented. Response matrices for deconvolution purpose were obtained.

Study on the influence of the B4C layer thickness on the neutron flux and energy distribution shape in multi-electrode ionisation chamber.

A model of a multi-electrode ionisation chamber, with polypropylene electrodes coated with a thin layer of B4C was created within Monte Carlo N-Particle Transport Code (MCNPX) and Fluktuierende Kaskade (FLUKA) codes. The influence of the layer thickness on neutron absorption in B4C and on the neutron spectra in the consecutive intra-electrode gas volumes has been studied using the MCNPX and FLUKA codes. The results will be used for designing the new type of the ionisation chamber.