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Tissue response of radiation therapy assessed by electrical impedance spectroscopy (EIS) in subcutaneous tumours in rats.

Persson, B. R. R. LU orcid ; Bauréus Koch, C. LU ; Grafström, G. LU and Salford, L. G. LU (2021) In Acta Scientiarum Lundensia 2021(002). p.1-19
Abstract

The present
investigation aims to evaluate the possibility of using bio-impedance
spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance
measurements performed with CythorLab™ equipped with a signal generator with a
known high output impedance and signal measuring device able to measure the voltage
applied by the generator. The control unit triggers the signal generator that
generates an MLS-sequence. The same control unit process the signal that
simultaneously measured by the voltage-recording device. An FFT analysis
performed to obtain the magnitude of the real and imaginary parts of the
impedance spectrum. The effect of various numbers of fractions... (More)

The present
investigation aims to evaluate the possibility of using bio-impedance
spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance
measurements performed with CythorLab™ equipped with a signal generator with a
known high output impedance and signal measuring device able to measure the voltage
applied by the generator. The control unit triggers the signal generator that
generates an MLS-sequence. The same control unit process the signal that
simultaneously measured by the voltage-recording device. An FFT analysis
performed to obtain the magnitude of the real and imaginary parts of the
impedance spectrum. The effect of various numbers of fractions of radiation therapy
(RT) on the impedance measured with surface plate electrodes investigated in male
rats of the Fischer-344 strain with rat glioma N32 tumours implanted subcutaneously
on the flank. Tumours produced by injecting 100 000 N32 tumour cells just below
the skin. Tumours were treated about four weeks after injection when a solid tumour
has developed with a diameter of 1-1.5 cm. Before treating the tumours, animals
anaesthetised, and the fur over the tumour shaven and carefully to ensure good
electrical contact between electrodes and skin. The electrical impedance dispersion
of tissue modelled with an RC-equivalent circuit from which collective
impedance parameters corresponding the cell membranes, Rm Cm intra -cellular
resistance, Ri, and extra-cellular resistance R0.Impedance measurements
performed over a tumour before irradiation to 5 Gy and every minute after the
irradiation up to 8 minutes. A slight increase of impedance, and with a time
constant of 10 minutes. The growth might be due to dry skin after irradiation
or a decrease of tumour vascularity during the treatment. The capacitance of
the cell membrane related to the characteristic frequency fc does not change
significantly before and after radiation exposure. A special parameter, the "Loss
Change Index" (LCI) which defined to vary between zero if there is no
change in the phase angle and one if the phase angle after exposure approach
zero. LCI reach an extreme at the characteristic frequency. The LCI value
recorded at the characteristic frequency fc varied with the accumulated absorbed
dose and fitted to a sigmoidal dose/response relationship.

(Less)
Abstract (Swedish)
Föreliggande undersökning syftar till att utvärdera möjligheten att använda bioimpedansspektrometri för att mäta tumör- och vävnadsrespons på strålterapi. Bioimpedansmätningar utförda med CythorLab ™ utrustade med en signalgenerator med en känd högutgångsimpedans och signalmätanordning som kan mäta spänningen som appliceras av generatorn. Styrenheten utlöser signalgeneratorn som genererar en MLS-sekvens. Samma styrenhet behandlar signalen som samtidigt mätes av spänningsregistreringsenheten. En FFT-analys utfördes för att erhålla storleken på de verkliga och imaginära delarna av impedansspektret.
Effekten av olika antal fraktioner av strålterapi (RT) på impedansen uppmätt med platt elektroder undersökta i han-råttor av... (More)
Föreliggande undersökning syftar till att utvärdera möjligheten att använda bioimpedansspektrometri för att mäta tumör- och vävnadsrespons på strålterapi. Bioimpedansmätningar utförda med CythorLab ™ utrustade med en signalgenerator med en känd högutgångsimpedans och signalmätanordning som kan mäta spänningen som appliceras av generatorn. Styrenheten utlöser signalgeneratorn som genererar en MLS-sekvens. Samma styrenhet behandlar signalen som samtidigt mätes av spänningsregistreringsenheten. En FFT-analys utfördes för att erhålla storleken på de verkliga och imaginära delarna av impedansspektret.
Effekten av olika antal fraktioner av strålterapi (RT) på impedansen uppmätt med platt elektroder undersökta i han-råttor av Fischer-344-stammen med råttgliom N32-tumörer implanterade subkutant på flanken. Tumörer som produceras genom att injicera 100 000 N32-tumörceller strax under huden. Tumörer behandlades ungefär fyra veckor efter injektion när en fast tumör har utvecklats med en diameter på 1-1,5 cm. Innan du behandlar tumörerna bedövade djuren och pälsen över tumören rakades och försiktigt för att säkerställa god elektrisk kontakt mellan elektroder och hud.
Den elektriska impedansdispersionen av vävnad modellerad med en RC-ekvivalent krets från vilken kollektiva impedansparametrar motsvarar cellmembranen, Rm Cm intracellulärt motstånd, Ri och extracellulärt motstånd R0.
Impedansmätningar utförda över en tumör före bestrålning till 5 Gy och varje minut efter bestrålningen upp till 8 minuter. En liten ökning av impedansen och med en tidskonstant på 10 minuter. Tillväxten kan bero på torr hud efter bestrålning eller minskad tumö-vaskularitet under behandlingen.
Kapacitansen hos cellmembranet relaterad till den karakteristiska frekvensen fc förändras inte signifikant före och efter strålningsexponering. En speciell parameter, "Loss Change Index" (LCI) som definierade att variera mellan noll om det inte finns någon förändring i fasvinkeln och en om fasvinkeln efter exponering närmar sig noll. LCI når en extremitet vid den karakteristiska frekvensen. LCI-värdet registrerat vid den karakteristiska frekvensen fc varierade med den ackumulerade absorberade dosen och anpassades till ett sigmoidalt dos vs
responsförhållande. (Less)
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; ; and
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alternative title
Vävnadsrespons av strålterapi bedömd med elektrisk impedansspektroskopi (EIS) i subkutana tumörer hos råttor.
publishing date
type
Contribution to journal
publication status
published
subject
keywords
radiation therapy,, bio-impedance spectrometry,, tissue response,, rat glioma, N32, N32 tumours, subcutaneous,, 60Co-gamma irradiation,, RC-circuit model,, cell membranes,, dose vs /response relation., Radiation therapy, Bio-impedance spectrometry,, Tissue response, CythorLab, Rat glioma, N32 tumours, Subcutaneous, 60Co-gamma irradiation, RC-circuit model, Cell membranes, Dose/response relation
in
Acta Scientiarum Lundensia
volume
2021
issue
002
pages
1 - 19
publisher
Bertil RR Persson, Medical Radiation Physics, 22185 Lund, Sweden
ISSN
1651-5013
language
English
LU publication?
yes
additional info
The work financially supported by John and Augusta Persson´s Foundation for scientific and medical research, Lund, and Swedish Cancer Foundation (contract 00 0220)
id
220c176a-ff5f-458c-8a01-159391140df3
date added to LUP
2021-05-02 20:56:56
date last changed
2021-05-03 13:05:46
@article{220c176a-ff5f-458c-8a01-159391140df3,
  abstract     = {{<p class="MsoNormal">The present<br>
investigation aims to evaluate the possibility of using bio-impedance<br>
spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance<br>
measurements performed with CythorLab™ equipped with a signal generator with a<br>
known high output impedance and signal measuring device able to measure the voltage<br>
applied by the generator. The control unit triggers the signal generator that<br>
generates an MLS-sequence. The same control unit process the signal that<br>
simultaneously measured by the voltage-recording device. An FFT analysis<br>
performed to obtain the magnitude of the real and imaginary parts of the<br>
impedance spectrum. The effect of various numbers of fractions of radiation therapy<br>
(RT) on the impedance measured with surface plate electrodes investigated in male<br>
rats of the Fischer-344 strain with rat glioma N32 tumours implanted subcutaneously<br>
on the flank. Tumours produced by injecting 100 000 N32 tumour cells just below<br>
the skin. Tumours were treated about four weeks after injection when a solid tumour<br>
has developed with a diameter of 1-1.5 cm. Before treating the tumours, animals<br>
anaesthetised, and the fur over the tumour shaven and carefully to ensure good<br>
electrical contact between electrodes and skin. The electrical impedance dispersion<br>
of tissue modelled with an RC-equivalent circuit from which collective<br>
impedance parameters corresponding the cell membranes, R<sub>m</sub> C<sub>m</sub> intra -cellular<br>
resistance, R<sub>i</sub>, and extra-cellular resistance R0.Impedance measurements<br>
performed over a tumour before irradiation to 5 Gy and every minute after the<br>
irradiation up to 8 minutes. A slight increase of impedance, and with a time<br>
constant of 10 minutes. The growth might be due to dry skin after irradiation<br>
or a decrease of tumour vascularity during the treatment. The capacitance of<br>
the cell membrane related to the characteristic frequency fc does not change<br>
significantly before and after radiation exposure. A special parameter, the "Loss<br>
Change Index" (LCI) which defined to vary between zero if there is no<br>
change in the phase angle and one if the phase angle after exposure approach<br>
zero. LCI reach an extreme at the characteristic frequency. The LCI value<br>
recorded at the characteristic frequency fc varied with the accumulated absorbed<br>
dose and fitted to a sigmoidal dose/response relationship.</p>}},
  author       = {{Persson, B. R. R. and Bauréus Koch, C. and Grafström, G. and Salford, L. G.}},
  issn         = {{1651-5013}},
  keywords     = {{radiation therapy,; bio-impedance spectrometry,; tissue response,; rat glioma, N32; N32 tumours; subcutaneous,; 60Co-gamma irradiation,; RC-circuit model,; cell membranes,; dose vs /response relation.; Radiation therapy; Bio-impedance spectrometry,; Tissue response; CythorLab; Rat glioma; N32 tumours; Subcutaneous; 60Co-gamma irradiation; RC-circuit model; Cell membranes; Dose/response relation}},
  language     = {{eng}},
  month        = {{04}},
  number       = {{002}},
  pages        = {{1--19}},
  publisher    = {{Bertil RR Persson, Medical Radiation Physics, 22185 Lund, Sweden}},
  series       = {{Acta Scientiarum Lundensia}},
  title        = {{Tissue response of radiation therapy assessed by electrical impedance spectroscopy (EIS) in subcutaneous tumours in rats.}},
  url          = {{https://lup.lub.lu.se/search/files/97345687/ASL_2021_003_ZRT_210430.pdf}},
  volume       = {{2021}},
  year         = {{2021}},
}