Hyperthermia properties of fiducial ... -...
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Paolo Arosio 1 , Matteo Avolio 2 , Letizia Bonizzoni 1 , Marco Cobianchi 2 , Salvatore Gallo 1 , Marco Gargano 1 , Nicola Ludwig 1 , Francesco Orsini 1 , Ivan Veronese 1 SAMPLES Typical gold fiducial markers, are dispersed in gel samples, using various geometric configurations simulating the actual position of the markers in the clinical practice. SCOPE Investigating the hyperthermia properties of the fiducial markers employed in Image-Guided Radiation Therapy (IGRT) under application of external alternating current field, in order to find out possible therapeutic effects, currently unexplored, and to study the physics mechanisms of the observed macroscopic effects. 1) Dipartimento di Fisica and INSTM, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy; 2) Dipartimento di Fisica and INSTM, Università degli Studi di Pavia, Via Bassi 6, 27100, Pavia, Italy; Hyperthermia properties of fiducial markers used in Image-Guided Radiation Therapy 3 mm x 1.2 mm Magnetic stimulation: - alternating current field (H AC ): from 7 to 20 kA/m - frequency from 100 to 1000 kHz EXPERIMENTAL SETUP Temperature measurement: - optical fiber based sensor - high resolution thermal camera (FLIR A065, 640x520 pixel, 0.05 K thermal resolution) RESULTS Temperature traces measured by the optical fiber for different fiducial configurations under the application of magnetic field. The optical fiber was positioned ~ 7 mm far from each fiducials. Thermal profile of few cm long passing over one fiducial, in agarose gel sample, registered at t= 120 s after starting the magnetic stimulation. The temperature of the fiducial appears low due to its very low emissivity (ε=0.01). Time A) B) C) D) Images of the hydrogel matrices acquired by the thermal camera at different times after starting the magnetic stimulation. A) one fiducial in agarose, B) three fiducials in agarose, C) one fiducial in PVA, D) three fiducials in PVA. CONCLUSIONS Preliminary results attested an increase of the temperature in the gel matrices as effect of the heating of the gold fiducial markers under a suitable magnetic stimulation. Hyperthermia evidences were also evaluated in the typical experimental conditions (2<H AC <15 kA/m and f=100 kHz) employed at present in Fluid Magnetic Hyperthermia clinical trials. Such evidences pave the way to extend the study to other types of fiducial markers and tissue samples, in order to interpret and model the observed phenomena. This project is supported by the Department of Physics in the frame of the “piano di sostegno alla ricerca 2015/17, linea 2, azione A”. H AC of 109.8 kHz and 16.15 kA/m Hydrogel matrices used as tissue mimicking materials: • 1.5% Agarose gel, • 8.0% Glutaraldehyde-crosslinked poly(vinyl alcohol) (PVA) gel External thermalization system (liquid tube circulating system connected to a reservoir at controlled temperature) used to reach a quasi-adiabatic condition MATERIAL CHARACTERIZATION The chemical composition of the samples was determined by XRF (Bruker Artax 200 spectrometer, filtered Mo anode tube, 40 kV and 0.8 mA, 0.65 mm spot diameter, 300 s) after cleaning in ultrasonic bath. The obtained spectra show an excellent agreement of the two cylindrical sample bases and a Au metallic standard (99.95% certified) Fiducial Optical fiber
Transcript of Hyperthermia properties of fiducial ... -...
Paolo Arosio1, Matteo Avolio2, Letizia Bonizzoni1, Marco Cobianchi2, Salvatore Gallo1, Marco Gargano1, Nicola Ludwig1, Francesco Orsini1, Ivan Veronese1
SAMPLES
Typical gold fiducial markers, are dispersed in gel samples,using various geometric configurations simulating theactual position of the markers in the clinical practice.
SCOPE Investigating the hyperthermia properties of the fiducial markers employed in Image-Guided Radiation Therapy (IGRT) underapplication of external alternating current field, in order to find out possible therapeutic effects, currently unexplored, and to study thephysics mechanisms of the observed macroscopic effects.
1) Dipartimento di Fisica and INSTM, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy;2) Dipartimento di Fisica and INSTM, Università degli Studi di Pavia, Via Bassi 6, 27100, Pavia, Italy;
Hyperthermia properties of fiducial markers used in Image-Guided Radiation Therapy
3 mm x 1.2 mm
Magnetic stimulation: - alternating current field (HAC):
from 7 to 20 kA/m- frequency from 100 to 1000 kHz
EXPERIMENTAL SETUP
Temperature measurement: - optical fiber based sensor
- high resolution thermal camera (FLIR A065, 640x520
pixel, 0.05 K thermal resolution)
RESULTS
Temperature traces measured by the opticalfiber for different fiducial configurations underthe application of magnetic field.The optical fiber was positioned ~ 7 mm farfrom each fiducials.
Thermal profile of few cm long passingover one fiducial, in agarose gel sample,registered at t= 120 s after starting themagnetic stimulation. The temperature ofthe fiducial appears low due to its verylow emissivity (ε=0.01).
Time
A)
B)
C)
D)
Images of the hydrogel matrices acquired by the thermal camera at different times after starting the magnetic stimulation. A) one fiducial in agarose, B) three fiducials in agarose, C) one fiducial in PVA, D) three fiducials in PVA.
CONCLUSIONS
Preliminary results attested an increase of the temperature in the gel matrices as effect of the heating of the gold fiducial markers under a suitable magnetic stimulation. Hyperthermia evidences were also evaluated in the typical experimental conditions (2<HAC<15 kA/m and f=100 kHz) employed at present in Fluid Magnetic Hyperthermia clinical trials. Such evidences pave the way to extend the study to other types of fiducial markers and tissue samples, in order to interpret and model the observed phenomena.This project is supported by the Department of Physics in the frame of the “piano di sostegno alla ricerca 2015/17, linea 2, azione A”.
HAC of 109.8 kHz and 16.15 kA/m
Hydrogel matrices used as tissue mimicking materials:• 1.5% Agarose gel,• 8.0% Glutaraldehyde-crosslinked
poly(vinyl alcohol) (PVA) gel
External thermalization system(liquid tube circulating systemconnected to a reservoir atcontrolled temperature) usedto reach a quasi-adiabaticcondition
MATERIAL CHARACTERIZATIONThe chemical composition of the samples was determined byXRF (Bruker Artax 200 spectrometer, filtered Mo anode tube,40 kV and 0.8 mA, 0.65 mm spot diameter, 300 s) aftercleaning in ultrasonic bath.
The obtained spectra showan excellent agreement ofthe two cylindrical samplebases and a Au metallicstandard (99.95% certified)
Fiducial
Optical fiber
