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Projects / Programmes source: ARIS

Development of in-vivo dosimetry for applications in radiotherapy

Research activity

Code Science Field Subfield
2.06.09  Engineering sciences and technologies  Systems and cybernetics  Medical physics 

Code Science Field
B140  Biomedical sciences  Clinical physics, radiology, tomography, medical instrumentation 

Code Science Field
2.06  Engineering and Technology  Medical engineering  
Keywords
in-vivo dosimetery, radiotherapy quality assurance, diamond detectors, RadFETs, brachytherapy
Evaluation (rules)
source: COBISS
Researchers (10)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  13976  MSc Janez Burger  Oncology  Researcher  2013 - 2016  28 
2.  09081  PhD Vladimir Cindro  Physics  Researcher  2013 - 2016  1,569 
3.  29519  PhD Rok Dolenec  Physics  Researcher  2014 - 2016  86 
4.  18277  PhD Andrej Gorišek  Physics  Researcher  2013 - 2016  1,330 
5.  18278  PhD Borut Paul Kerševan  Physics  Researcher  2013 - 2016  1,327 
6.  12224  PhD Borut Kragelj  Oncology  Researcher  2013 - 2016  81 
7.  15642  PhD Gregor Kramberger  Physics  Head  2013 - 2016  1,470 
8.  12313  PhD Igor Mandić  Physics  Researcher  2013 - 2016  1,464 
9.  04361  Erik Margan    Technical associate  2013 - 2016  34 
10.  11985  PhD Marko Zavrtanik  Physics  Researcher  2013 - 2016  1,024 
Organisations (3)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,038 
2.  0302  Institute of Oncology Ljubljana  Ljubljana  5055733000  15,390 
3.  1554  University of Ljubljana, Faculty of Mathematics and Physics  Ljubljana  1627007  33,822 
Abstract
The project aims for development of technologies which lead to construction of one or two dimensional dosimetric sensors fields for in-vivo dosimetry in medical applications, mainly radiotherapies. The sensor technologies chosen for investigation are mono-crystalline diamond detectors and special p-MOSFET transistors (RadFET). Both sensor types differ in almost all relevant parameters: crystal properties (atomic number Z), the radiation detection principle, geometry and readout, hence represent a complementary choice. Dosimeters will be hosted by a thin ()=50 mm) flexible printed circuits with a minimum pitch of 100 mm. In addition to the consequent reduced influence of substrate material to the measured dose for X and g rays, the flexible circuits will enable construction of different sensor patterns at small printed circuit dimensions (large density of sensors). As an example of in-vivo dosimetric array a linear sensor array (dosimeter) with diameter of (2 mm will be developed. Such dimensions roughly correspond to the thickness of the catheter inserted in the tumour during PDR/HDR (High Dose Rate/Pulse Dose Rate) brachytherapy. During the brachytherapy an after-loading applicator inserts a highly active radioisotope 192Ir to different locations in the catheters and in such a way delivers the dose to the carcinoma. The dosimeter will consist of 5-10 sensors (size ~mm3) stretched over ~10 cm distance. It will enable in-vivo dose measurements at known points in the tumour and will contribute to much higher quality of the therapy: cross-check of the treatment plan, on-line correction of the treatment plan, damage assessment to the cancerous and healthy tissue. Arrays of sensitive dosimetric sensors (sensitive from ~10-4-10-3 Gy) can also be exploited for tracking the source locations during the treatment in brachytherapy and therefore contributes to the quality assurance of the treatment. One of the main goals of the project is therefore the development of multi-channel (~2x10 channels) readout electronics, which will be read out on the scale of seconds. The readout electronics will be connected to the PC, which will monitor the readout electronics and provide the user interface to the measurements. The development of the in-vivo dosimetry will be supported by Monte-Carlo simulation, which is of crucial importance for understanding the measurements and calibration of the dosimeters. The software tools will be modular and therefore enable fast adaptation to any other sensor array or/and application. Sensors and sensor arrays will be extensively tested in the system for sensor characterization with electrons from 90Sr source and X-rays and also in phantom with therapeutic source (192Ir).
Significance for science
Scientific importance of the project is discovery of charge multiplication in single crystalline diamond detectors, which was a first such observation in the world. Also important is measurement of specific ionization of 90Sr electrons in diamond detectors. The sensitivity measurements of different RadFET sensors at different photon energies are important, particularly when used in unknown radiation fields, such as frequently encountered in nuclear applications. Important are also measurements of temperature dependence of RadFET response and its annealing after irradiations. The development of multi-channel continuous sensor readers, precise pico-ampere meter and pulsed RadFET reader is also important particularly in building complex sensor arrays. They encompass solutions for reading out dosimetry sensors which are unique.
Significance for the country
The project contributes to improved use of radiation sensors in medicine and nuclear applications. The knowledge gained in the project allows us to setup complex dosimetry arrays and has also a commercial potential. The technology for production of the readers was transferred to company Particulars d.o.o. The most important achievement would be the use of developed sensor arrays during the treatments in oncology. It would lead to more successful treatment and smaller probability of mistakes. Sensors technologies, diamond detectors and RadFETs with accompanied readout systems are suitable for the use in radiotherapies. In addition the software tools were developed which can be used to independently verify dose distributions obtained with commercial software. A transfer of knowledge to students is also important (MSc. thesis). As a part of the Physics experiments subject in last two years of undergraduate study, a demonstrator dosimetry system will be setup for introduction of the field of dosimetry to the students.
Most important scientific results Annual report 2014, 2015, final report
Most important socioeconomically and culturally relevant results Annual report 2014, 2015, final report
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