Batteryless NFC dosimeter tag for ionizing radiation based on commercial MOSFET

This paper reports the development, evaluation and validation of DosiTag, a dosimetric platform based on Near Field Communication (NFC) technology. The designed system comprises two main parts: a passive NFC sensing tag as the dosimeter unit, which includes a commercial P-channel MOSFET transistor as radiation sensor; and an NFC-enabled smartphone running a custom-developed application as the reader unit. Additionally, a cloud service based on the messaging protocol Message Queue Telemetry Transport (MQTT) has been implemented using a broker/client architecture to allow the storage and classification of the patient’s data. The dosimeter tag was designed using commercial low-power integrated circuits (ICs) and it can operate without any external power supply or battery, being supplied by the smartphone through the radio frequency (RF) energy harvested from the NFC link. The radiation dose is measured through the increase of the DMOS transistor source voltage using the smartphone as the reader unit. Two tag prototypes have been characterized with a 6 MV photon beam and radiation doses up to 57 Gy and 42 Gy, respectively. The achieved average sensitivity is (4.37 ± 0.04) mV/ Gy with a resolution of 2 cGy, which goes beyond the state-of-the-art of previous NFC dosimeters and places DosiTag as a low-cost promising electronic platform for dose control in radiotherapy treatments.Junta de Andalucía (Spain), projects numbers PI-0505–2017 FEDER/Junta de Andalucía- Consejería de Economía y Conocimiento Project B-TIC-468-UGR18Proyecto del Plan Nacional I + D: PID2019–104888GB-I00 and Proyectos I + D + i Junta de Andalucía 2018: P18-RT-3237H2020 ELICSIR project (grant No. 857558)Grant IJC2020-043307-I funded by MCIN/AEI/ 10.13039/501100011033European Union NextGenerationEU/ PRT

Development and characterization of remote radiation dosimetry systems using optically stimulated luminescence of Al2O3:C and KBr:Eu

Scope and Method of Study: To develop and test the performance of two different dosimetry systems; one for in situ, high-sensitivity, inexpensive environmental monitoring, and another for near-real-time medical dosimetry. The systems are based on remote interrogation of the optically stimulated luminescence (OSL) from Al2O3:C and KBr:Eu single crystal dosimeters (exposed to environmental and medical radiation fields, respectively) via fiber optic cables. The environmental system was tested in lab conditions using various radioactive sources including 60 Co, 90 Sr, 137 Cs, and 226 Ra, as well as with 232 Th-enriched soil stimulant. The medical system was tested under various diagnostic x-ray systems, including fluoroscopy and computed tomography (CT) machines, as well as with high dose rate 192 Ir brachytherapy sources and 232 MeV proton therapy beams under simulated treatment conditions.Findings and Conclusions: The environmental system was shown to achieve sensitivity high enough for measuring an OSL signal resulting from a dose of ~1 uGY, which is equivalent to ~12 hours of natural background radiation. This sensitivity allows for monitoring of the radiation characteristics of a natural environment more rapidly and/or less expensively than existing methods, such as soil sampling and in situ gamma spectroscopy. The KBr:Eu-based medical system results show that the near-real-time data acquisition during irradiation allows for rapid quality assurance (QA) measurements that benefits from high spatial resolution. These features are not present in most current standard dosimeters such as thermoluminescent detectors and pencil ionization chambers. The dosimeter does exhibit energy dependence, and a sensitization during high dose rate procedures. As a result, a model has been proposed that provides a description of the possible mechanisms that govern the transfer of electrons and holes within KBr:Eu during OSL measurement at room temperature. Correction factors for these effects must be investigated for the system to become relevant for accurate dosimetry, rather than rapid QA

The Design of X-Ray Film Reader with Film Presence Detector

X-Ray viewer is a tool for observing the results of X-Ray films using ray lighting. It aims to get clearer readings of X-Ray films by radiographers and doctors. X-Ray viewers in hospitals generally cannot be carried anywhere because they use fluorescent lamps as a source of radiation and use 220 Volt AC voltage directly. So that its use is less effective and efficient because it must be connected directly to a 220 Volt AC power source and requires large power. In this regard the author wants to design an X-Ray viewer tool that can be used to read the results of X-Ray films clearly and is portable so that the device can be used anywhere because it uses a battery as a voltage source and is equipped with a presence detection sensor film in order to save energy so that the use of tools is more effective and efficient

Wireless In-Vivo Dosimetry of High Dose Rate Brachytherapy for Prostate Cancer using MOSkin Detectors

High Dose Rate brachytherapy is an effective treatment modality for prostate cancer due to the radio-sensitivity of the tumour and short treatment time. This procedure has strong radiation concentration and a steep dose gradient but no acceptable dose verification method to ensure prescribed dose is delivered to minimise damage to tumour-adjacent organs. With radiation emitted directly into the tumour, the most effective monitoring method is in-vivo dosimetry. A new MOSkinTM readout system, OneTouch, has been developed to provide real time dosimetric readouts and temperature variation compensation during in-vivo dosimetry. Through the additional of detectors to the rectal ultrasound probes used during brachytherapy, dosimetric and anatomical data can be transmitted. Two generations of MOSkinTM detectors were analysed through angular and sensitivity testing; the circular gate version proved superior normalised angular dose response of ±1.5% and sensitivity drift of -8.41±0.67%, compared to -28.24±1.19% with the parallel gate design. MOSkinTM detectors are an accurate in-vivo dosimeter, with normalised agreement to the treatment plan of 1.06±0.1 compared to radiochromic film normalised agreement of 1.10±0.01. The OneTouch and MOSkinTM system proved clinically viable and will further improve the safety of prostate cancer treatment through HDR brachytherapy

Follow up of Cs-137 activity in the first 100 samples in the area of Kumodraz, Belgrade in the 2008 to 2011 period

This paper presents results of gamma spectrometric analyses of air samples, collected in the period from 2008 to 2011, at Kumodraz location. Cs-137 specific activity has been monitored for 4 years. Exposure rate of gamma background radiation has been showed, as well. Obtained results show that average annual effective doses are in the range from 1.01 to 1.19 mSv/y and lower than the worldwide average.I International Conference on Radiation in Various Fields of Research : RAD 2017 : proceedings book; April 25-27, 2012; Niš, Serbi

Methods for therapeutic optimization in radiation therapy: from dose measurement to NTCP modelling

The purpose of this thesis is to develop methods and materials for radiation therapy optimization from dose measurement to Normal Tissue Complication Probability (NTCP) modelling. The research activity focuses on two topics of the optimization problem: development of new optical fiber sensor dosimeters and investigation of standard dosimeters for small field and in vivo dosimetry and dose optimization to the organs at risk. The project aims to realize a passive detector for ionizing radiation based on optical fiber sensor technology suitable for radiation dosimetry in a dose range relevant to clinical practice. Optical fiber sensors have been characterized identifying the physical quantities involved in the interaction and modelling the interaction process between ionizing radiation and the fiber material. Dose response of fiber Bragg gratings, resonant cavities and thermoluminescent dosimeters (TLDs) have been investigated, under conventional photon beam and non-conventional accelerator beam, such as high dose-per-pulse electron beams. The results of the investigation has demonstrated the great potential of optical fiber sensors in radiation therapy procedures as well as in radiation monitoring and protection in medicine. The study also demonstrated that the TLD dose response in high dose-per-pulse electron beams has a parabolic behavior for doses under 10 Gy, assessing that TLD-100 may be useful detectors for intraoperative electron radiation therapy patient dosimetry if a proper calibration is provided. The accuracy of the verification of the delivered dose is strictly jointed with clinical efficacy of radiotherapy treatments. Radiotherapy optimization and many advances in technology and techniques are aimed at improving the balance between the tumor control probability (TCP) and the normal tissue complication probability, i.e. maximizing tumor control while maintaining tissue complications at an acceptable level. The steepness of the given TCP or NTCP curve versus dose defines the change in response expected for a given change in delivered dose. Thus, dosimetric uncertainties in the dose delivered will translate directly into changes in TCP and NTCP for the population of patients involved. Improving the predictive power of NTCP model itself, improve the accuracy in predicting clinical outcome and concurs to the optimization strategy. The present work provides multi-variables predictive models for several toxicity endpoint of organ at risks and different cancer patients treated with conformal radiation therapy. The potential role of data-driven multi-variable models respect to classical predictive risk models is the possibility to include in the analysis clinical patient-specific factors in addition to dosimetric variables of several radiation-involved organs. Multi-organs interaction in affecting diseases at a specific site have been evidenced suggesting the need to consider the normal tissue complication modelling a complex process involving multiple biological pathways and systems

HDR brachytherapy: improved methods of implementation and quality assurance

This thesis describes experimental work performed (1998-2001) during the author's involvement with the Brachytherapy group at the Peter MacCallum Cancer Centre (PMCC), where he was employed by its Department of Physical Sciences and subsequent modeling and analytical studies. When PMCC added HDR brachytherapy to its radiation therapy practice, an existing operating suite was considered the ideal location for such procedures to be carried out. The integration of brachytherapy into the theatre environment was considered logical due to the relatively invasive nature of brachytherapy techniques and the availability of medical equipment. This thesis contains the detailed study of three key Research Questions involved in clinical aspects relating to quality assurance of an HDR brachytherapy practice. An investigative chapter is dedicated to the pursuit of each of the Research Question s. The first question asked… Is the novel approach to using modular shielding combined with time and distance constraints adequately optimized during HDR brachytherapy? In order to establish optimal clinical practices, this project evaluates the effectiveness of additional shielding added to the modular shielding system without modification of the previously determined time and distance constraints for PMCC staff, other patients, and member of the public. The DOSXYZnrc user code for the EGSnrc Monte Carlo radiation transport code has been used to model exposure pathways to strategic locations used for measurement in and around the operating theatre suite. Modeling allowed exposure pathways to various areas with the facility to be tested without the need to use real sources. The second Research Question asked… How well is dose anisotropy characterized in the near field range of the clinic's HDR 192Ir source? This study experimentally investigated the anisotropy of dose around a 192Ir HDR source in a water phantom using MOSFETs as relative dosimeters. In addition, modeling using the DOSRZnrc user code for the EGSnrc Monte Carlo radiation transport code was performed to provide a complete dose distribution consistent with the MOSFET measurements. Measurements performed for radial distances from 5 to 30 mm extend the range of measurements to 5 mm which has not been previously reported for this source construction. The third Research Question is aimed at the patient level. Is the dose delivered to in vivo dosimeters, located within critical anatomical structures near the prostate, within acceptable clinical tolerance for a large group of HDR prostate patients? An in vivo dosimetry technique employing TLDs to experimentally measure doses delivered to the urethra and rectum during HDR prostate brachytherapy was investigated. Urethral and rectal in vivo measurements for 56 patients have been performed in the initial fraction of four-fraction brachytherapy boost. In the absence of comparable in vivo data, the following local corrective action level was initially proposed: more than 50% of the prostatic urethra receiving a dose 10% beyond the urethral tolerance. The level for investigative action is considered from the analyses of dose differences between measured data and TPS calculation

A design concept for radiation hardened RADFET readout system for space applications

Instruments for measuring the absorbed dose and dose rate under radiation exposure, known as radiation dosimeters, are indispensable in space missions. They are composed of radiation sensors that generate current or voltage response when exposed to ionizing radiation, and processing electronics for computing the absorbed dose and dose rate. Among a wide range of existing radiation sensors, the Radiation Sensitive Field Effect Transistors (RADFETs) have unique advantages for absorbed dose measurement, and a proven record of successful exploitation in space missions. It has been shown that the RADFETs may be also used for the dose rate monitoring. In that regard, we propose a unique design concept that supports the simultaneous operation of a single RADFET as absorbed dose and dose rate monitor. This enables to reduce the cost of implementation, since the need for other types of radiation sensors can be minimized or eliminated. For processing the RADFET's response we propose a readout system composed of analog signal conditioner (ASC) and a self-adaptive multiprocessing system-on-chip (MPSoC). The soft error rate of MPSoC is monitored in real time with embedded sensors, allowing the autonomous switching between three operating modes (high-performance, de-stress and fault-tolerant), according to the application requirements and radiation conditions

Evaluation of the region-specific risks of accidental radioactive releases from the European Spallation Source

The European Spallation Source (ESS) is a neutron research facility under construction in southern Sweden. The facility will produce a wide range ofradionuclides that could be released into the environment. Some radionuclides are of particular concern such as the rare earth gadolinium-148. In this article, the local environment was investigated in terms of food production and rare earth element concentration in soil. The collected data will later be used to model thetransfer of radioactive contaminations from the ESS

Follow up of Cs-137 activity in the first 100 samples in the area of Kumodraz, Belgrade in the 2008 to 2011 period

This paper presents results of gamma spectrometric analyses of air samples, collected in the period from 2009 to 2011, at Kumodraz location. Cs-137 specific activity has been monitored for 4 years. Exposure rate of gamma background radiation has been showed, as well. Obtained results show that average annual effective doses are in the range from 1.01 to 1.19 mSv/y and lower than the worldwide average.I International Conference on Radiation in Various Fields of Research : RAD 2017 : proceedings book; April 25-27, 2012; Niš, Serbi