M. Paolucci

Use of a CMOS Image Sensor for an Active Personal Dosimeter in Interventional Radiology

Interventional radiologists and staff members, during all their professional activities, are frequently exposed to protracted and fractionated low doses of ionizing radiation. Due to skin tissues and peripheral blood irradiation, these exposures can result in deterministic effects (radiodermatitis, aged skin, and hand depilation) or stochastic ones (skin and non-solid cancer incidence). The authors present a novel approach to perform online monitoring of the staff during their interventions by using a device based on an Active Pixel Sensor. The performance of the sensor as an X-ray radiation detector has been evaluated with a proper experimental setup: the number of photons and the generated charge have been assessed as dosimetric observables from the frames acquired by the sensor using a two-threshold clustering algorithm, the efficiency of which has been evaluated as well. The correlation of these observables with passive dosimeter dose measurements has been analyzed: a good linearity has been demonstrated, and the response difference between pulsed and continuous operational modes is reduced to less than 10%, marking a distinct improvement with respect to commercial Active Personal Dosimeters.

Performance of CMOS imager as sensing element for a Real-time Active Pixel Dosimeter for Interventional Radiology procedures

Staff members applying Interventional Radiology procedures are exposed to ionizing radiation, which can induce detrimental effects to the human body, and requires an improvement of radiation protection. This paper is focused on the study of the sensor element for a wireless real-time dosimeter to be worn by the medical staff during the interventional radiology procedures, in the framework of the Real-Time Active PIxel Dosimetry (RAPID) INFN project. We characterize a CMOS imager to be used as detection element for the photons scattered by the patient body. The CMOS imager has been first characterized in laboratory using fluorescence X-ray sources, then a PMMA phantom has been used to diffuse the X-ray photons from an angiography system. Different operating conditions have been used to test the detector response in realistic situations, by varying the X-ray tube parameters (continuous/pulsed mode, tube voltage and current, pulse parameters), the sensor parameters (gain, integration time) and the relative distance between sensor and phantom. The sensor response has been compared with measurements performed using passive dosimeters (TLD) and also with a certified beam, in an accredited calibration centre, in order to obtain an absolute calibration. The results are very encouraging, with dose and dose rate measurement uncertainties below the 10% level even for the most demanding Interventional Radiology protocols.

Experimental Characterization of a Wireless Personal Sensor Node for the Dosimetry During Interventional Radiology Procedures

Wireless sensor networks featuring portable devices are widely used for healthcare applications such as real-time patient monitoring. For such applications, design constraints are limited in the amount of energy, network capacity (short communication range and low bandwidth), and processing and memory resources in each node. In the framework of the real-time active pixel dosimetry project, the attention has been focused on the design of a dosimetric system for online dose monitoring of interventional radiology (IRad) operators. This paper describes the experimental characterization of the prototype used during several IRad procedures. The wireless link of the prototype has been characterized by measuring the packet error rate of the network in different scenarios: the worst obtained result was lower than 0.4%, which is acceptable for the specific application. The prototype has also been compared with a reference acquisition system to fully validate the system in operating condition. A linear correlation has been observed between the observables for all the working conditions. Moreover, the average pixel response could be used as an indicator of the goodness of the data acquisition for a given procedure showing that it does not depend on the procedure, hence on the particular spectrum of the diffused radiation. Finally, the measurement of absorbed dose (μGy) has been calculated for different IRad procedures.

Personnel real time dosimetry in interventional radiology

Interventional radiology and hemodynamic procedures have rapidly grown in number in the past decade, increasing the importance of personnel dosimetry not only for patients but also for medical staff. The optimization of the absorbed dose during operations is one of the goals that fostered the development of real-time dosimetric systems. Indeed, introducing proper procedure optimization, like correlating dose rate measurements with medical staff position inside the operating room, the absorbed dose could be reduced. Real-time dose measurements would greatly facilitate this task through real-time monitoring and automatic data recording. Besides real-time dose monitoring could allow automatic data recording. In this work, we will describe the calibration and validation of a wireless real-time prototype dosimeter based on a new sensor device (CMOS imager). The validation measurement campaign in clinical conditions has demonstrated the prototype capability of measuring dose-rates with a frequency in the range of few Hz, and an uncertainty smaller than 10%.

An active pixel sensor to detect diffused X-ray during Interventional Radiology procedure

Interventional radiologists and staff members are frequently exposed to protracted and fractionated low doses of ionizing radiation due to diffused X-ray radiation. The authors propose a novel approach to monitor on line staff during their interventions by using a device based on an Active Pixel Sensor developed for tracking applications. Two different photodiode configurations have been tested in standard Interventional Radiology working conditions. Both options have demonstrated the capability to measure the photon flux and the energy flux to a sufficient degree of uncertainty.

Quality management system for laser equipment: The experience of USL Umbria 2

Introduction The development process of USL Umbria 2 Quality Management System (QMS) led, from 2008, to ISO9001:2008 Certification of the Medical Physics Department (MPD) activities. Purpose In this framework, in addition to the application of its own QMS, the MPD works in partnerships with all departments and structures which use ionizing and non-ionizing radiation facilities included medical LASER equipment. Materials and methods QMS for LASER equipment consists of: • Design of work processes, with realization of the related forms and safety signs. • Recognition of laser equipment and environmental and individual protection devices within our medical institution. • Realization of a dedicated Quality Assurance program, with the implementation of a technical protocol, planning and execution of quality and functional tests using calibrated measuring devices, recording and storage system of Quality Controls performed. • Design and realization of Laser Safety Management System with draft of Safety Guidance and training course program for hospital staff exposed to LASER risks. Results Our project has been performed over a period of about six years, its application led to an optimization of the distribution of the LASER equipment in all the USL Umbria 2 health facilities (17 structures, including hospitals and health districts), where classes 3B and 4 LASER equipment are installed and used for various applications. Conclusions The quality and functional checks, included staff training, have highlighted the need to continuous verification in order to provide the proper protection to patients and operators during clinical activities.

From xray to display: A quality management system workflow for production and visualization of radiological images

Introduction In 2013 the unification of two different public health companies led to the need of technological integration of RIS-PACS system in order to optimize the patient data management of all the diagnostic radiology department. Purpose Implementation of a quality assurance program, following the national and international laws and regulations, of xray imaging production and visualization system, integrated in the ISO 9001:2008 standards. Materials and methods Quality Assurance (QA) program is developed in many steps, starting from census and classification of all the equipment (Computed Radiography, Direct Radiology, Work Station, ecc.), through acceptance tests and constancy test program, made in association with the radiology department staff. The activity involved different instrumentation and home-made software, made by open source solution, dedicated to the management of data acquisition and analysis. Results Quality management system allows us to check in real time all the display, using a dedicated software platform controlled from the Medical Physics Department office, with a time sparing related to the huge extension of the local health trust. Conclusions The QA program of CR and DR system, after three years, led the possibility to renew the oldest equipment and, at the same time, the optimization of the image quality related to dosimetric parameters, following the ALARA principles, with a better uniformity of image reporting.

179: Characterization of wireless personal dosimeter prototype for Interventional Radiology medical operators

VI. CONCLUSIONS • Main features of the commercially available active personal dosimeters: − semiconductor technology − real-time evaluation of dose and/or dose rate − alarm at a pre-set dose and/or dose rate < level (opt.). Performance is not satisfactory for X-ray fields used in IR procedures (low energies and pulsed fields) [Villani, 2013]. With pulsed X-ray beams the response decreases: − as the dose equivalent rate increases − from 10 to 40% when pulse rate increases from 1 to 20 pps.

A Dosimetric Device Based on CMOS Image Sensor for Interventional Radiology

Interventional radiologists and staff members, during all their professional activities, are frequently exposed to protracted and fractionated low doses of ionizing radiation. The authors present a novel approach to perform on line monitoring of the staff during their interventions by using a device based on an Active Pixel Sensor (APS). The performance of the sensor as an X-ray radiation detector has been evaluated with a proper experimental set-up: the number of photons and the generated charge have been assessed as dosimetric observables. The correlation of these observables with the dose measured by the passive dosimeters has been analyzed: a good linearity has been demonstrated and the response difference between pulsed and continuous operational modes is reduced to less than 10 %, marking a distinct improvement with respect to commercial Active Personal Dosimeters.