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This report describes dosimetry techniques used by EURADOS Working Group 9 (Radiation Dosimetry in Radiotherapy) to measure out-of -field doses for use in radiotherapy. Several passive dosimeter types were used, based on the physical principles of thermoluminescence (TLD), optically simulated luminescence (OSL) and radiophotoluminescence (RPL), in addition to an ionization chamber used as a reference standard. Superheated drop, bubble damage and track etch detectors were used specifically for neutron measurements. In this report, doses were measured in a water tank to obtain a matrix of out-of-field measurement points and in a BOMAB-like phantom to simulate a prostate treatment. The experimental aspects of the project involved a collaboration between eight European institutions, the Ruđer Bošković Institute , Zagreb, Croatia, the Institute of Nuclear Physics, Krakow, Poland, the Commissariat à l’Energie Atomique, Saclay, France, the Santa Chiara University Hospital, Pisa, Italy, the Belgian Nuclear Research Institute, Mol, Belgium, the Universitat Autònoma de Barcelona, Bellaterra, Spain, the Università di Pisa, Italy and the Politecnico di Milano, Italy. After an introduction and project outline, chapter 3 describes the physical aspects and calibration of the dosimeters used and is followed in chapters 4, 5 and 6 by a description of water tank measurements at lateral distances from the isocentre up to 56 cm and at depths of 10-25 cm. TLD, OSL and RPL dosimeters were compared both within and outside the beam. Within the beam, agreement between TLDs and ionization chamber results was + 1.5% and greater discrepancies were observed for OSL and RPL dosimeters, the latter due to a high atomic number cap. Outside the beam, good agreement with ionization chamber measurements wasobserved for both TLDs and RPLs. However, OSL results showed an increasing overestimation of dose with distance from the isocentre and a correction was required. Chapter 7 describes the BOMAB-like phantom used for the simulation of a prostate treatment. This was undertaken using Varian Clinac 2300 linear accelerators to simulate treatments for the following conditions: (i) 6MV 4-field CRT (ii) 15MV 5-field CRT (iii) 18MV 4-field CRT (iv) 6MV IMRT (v) 18MV IMRT (vi) 6MV VMAT (vii) 6MV Tomotherapy1. Measurements were compared with treatment planning system (TPS) calculations of the doses at the measurement points and out-of -field dose underestimates were identified. Chapters 8 and 9 discuss the results of the BOMAB phantom experiments for photon absorbed doses and neutron dose equivalents. For the latter, neutron dosimeters showed consistent and repeatable responses. A non-negligible photoneutron dose was observed for a 6 MV primary photon beam. A short summary of some risk models for second cancer induction is given in Chapter 10.

International audience; Purpose To characterize stray radiation around the target volume in scanning proton therapy and study the performance of active neutron monitors. Methods Working Group 9 of the European Radiation Dosimetry Group (EURADOS WG9-Radiation protection in medicine) carried out a large measurement campaign at the Trento Centro di Protonterapia (Trento, Italy) in order to determine the neutron spectra near the patient using two extended-range Bonner sphere spectrometry (BSS) systems. In addition, the work focused on acknowledging the performance of different commercial active dosimetry systems when measuring neutron ambient dose equivalents, H∗(10), at several positions inside (8 positions) and outside (3 positions) the treatment room. Detectors included three TEPCs-tissue equivalent proportional counters (Hawk type from Far West Technology, Inc.) and six rem-counters (WENDI-II, LB 6411, RadEye™ NL, a regular and an extended-range NM2B). Meanwhile, the photon component of stray radiation was deduced from the low-lineal energy transfer part of TEPC spectra or measured using a Thermo Scientific™ FH-40G survey meter. Experiments involved a water tank phantom (60 × 30 × 30 cm3) representing the patient that was uniformly irradiated using a 3 mm spot diameter proton pencil beam with 10 cm modulation width, 19.95 cm distal beam range, and 10 × 10 cm2 field size. Results Neutron spectrometry around the target volume showed two main components at the thermal and fast energy ranges. The study also revealed the large dependence of the energy distribution of neutrons, and consequently of out-of-field doses, on the primary beam direction (directional emission of intranuclear cascade neutrons) and energy (spectral composition of secondary neutrons). In addition, neutron mapping within the facility was conducted and showed the highest H∗(10) value of ∼51 μSvGy-1; this was measured at 1.15 m along the beam axis. H∗(10) values significantly decreased with distance and angular position with respect to beam axis falling below 2 nSv Gy-1 at the entrance of the maze, at the door outside the room and below detection limit in the gantry control room, and at an adjacent room (

In our previous work (Milković et al., 2009) the influence of the working method of radiology technicians on the exposure of children patients during X- ray diagnostic of thorax was shown. The aims of this work were to present the dose reduction of the patients after education of the staff and to determine the influence of human working method on the exposure of children patients during the X- ray diagnostic of sinus. The dose on patient in the primary beam was measured systematically with RPL and TLD dosimeters during the X-ray diagnostic of chest and sinus in children between the age 7 and 16 years. Measurements were made in Children Hospital Srebrnjak, Department of Radiology. 40 and 30 patients were chosen for thorax and sinus measurements, respectively. The X-ray diagnostic examinations were carried out by 3 technicians. In the original work (Milković et al., 2009) the average primary surface doses were in the range of 0.14-0.17 mSv for two technicians, higher doses (average 0.35 mSv) were found on the patients examined by the third technician. Additional consulting and education resulted in significant dose reduction (average on 20 patients decreased to 0.14 mSv) for that technician. In all cases the doses were compared to the body mass index of the patients. The doses did not differ significantly during sinus X-ray examination carried out by different technicians (average for all 3 technicians was 0.95 ± 0.17 mSv). This research on children patients during X-ray diagnostics of chest and sinus has showed that: a) Dosimetry measurement even in every day X-ray diagnostic is very useful to show the possible deficiency in radiation protection measures, b) The dose on patients depends also on the human working method, c) Adequate education of technicians can improve the radiation protection of patients. Reference: Đ. Milković, N. Beck, M. Ranogajec-Komor, Ž. Knežević, S. Miljanić and F. Rubić: Influence of human working method on the patient dose in chest X-ray diagnostic measured with TL and RPL dosimeters, Proc. of 5th International Workshop on Individual Monitoring, Oarai, Japan. 28-29 Nov, 2009 (Yamamoto, T. Ed.), Oarai, Japan, Chiyoda Technol Corporation. pp. 133-146 (2010).

The metrology of high-energy neutron fields is important because of the increase in the number of high-energy accelerators in research and medicine in Europe, where high-energy neutrons are the dominant component of the radiation field present outside the shielding ; high-energy neutrons can also be a secondary component of the fields in the beam delivery system and in the patient’s body in hadrontherapy and the occupational exposure to cosmic radiation where highenergy neutrons are a significant component of the total cosmic radiation field in aircraft and in spacecraft. The energy range of neutrons in these fields extends from thermal energies to several gigaelectron volts.