The emergence of hyperthermia as a cancer therapy has been an exciting clinical development even though its potential is still unknown. One of the main problems has been correlating the observed tumor response with the temperature distributions achieved during treatment. Lack of knowledge of complete temperature distributions within the target tissue volume has lead to confusing and conflicting results which will ultimately be used to draw conclusions about hyperthermia as a clinical cancer therapy if treatment monitoring capabilities are not improved. The principal hypothesis of the proposed work is that electrical impedance changes recorded f=during hyperthermia cancer treatment are indicators which can be used to improve the monitoring and assessment of therapy delivery. To evaluate this hypothesis, electrical impedance imaging (EIT) techniques will be used to estimate temperature distributions through differential changes in reconstructed impedance profiles which will be correlated to temperature rise through empirical relationships and directly measured temperature data. While EIT is generally viewed as an imaging modality of low resolution and moderate sensitivity, the approach taken in this research counteracts some of these limitations by using internal measurements and other a priori data along with sophisticated reconstruction algorithms based on the finite element method. A prototype EIT imager has been developed and preliminary results obtained during phantom heating experiments have been promising and have suggested that temperature sensitivities on the order of 0.5 degrees Celsius are achievable in a practical setting. The research proposed as part of this project focuses on the realization of a second generation system which involves several significant hardware and software advancements including 3D imaging capabilities. Extensive in vitro and in vivo testing a of these improvements will be conducted to quantify overall system performance and potential as a thermal imaging technique for estimating temperature fields during hyperthermia delivery. If the objectives of this project can be met a valuable tool for providing desperately needed thermal data on clinically induced hyperthermia will have been realized. With the knowledge of complete temperature distributions that appears possible using EIT, relationships between therapeutic outcome and variation in tumor temperature distributions can be determined. Then, the sensitivity of the desired temperature profile to controllable treatment parameters can be systematically studied and treatment protocols which maintain a high likelihood of achieving the desired response can be developed and the efficacy of hyperthermia established based on a strong clinical rationale.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA064588-04
Application #
2667989
Study Section
Special Emphasis Panel (ZRG3-RAD (01))
Program Officer
Mahoney, Francis J
Project Start
1995-05-01
Project End
1999-02-28
Budget Start
1998-03-01
Budget End
1999-02-28
Support Year
4
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Dartmouth College
Department
Type
Schools of Engineering
DUNS #
041027822
City
Hanover
State
NH
Country
United States
Zip Code
03755
Skourou, Christina; Hoopes, P Jack; Gibbs-Strauss, Summer L et al. (2009) High dose rate radiation treatment of experimental intramuscular prostate carcinoma. Int J Radiat Biol 85:330-7
Skourou, Christina; Hoopes, P Jack; Strawbridge, Rendall R et al. (2004) Feasibility studies of electrical impedance spectroscopy for early tumor detection in rats. Physiol Meas 25:335-46
Osterman, K Sunshine; Hoopes, P Jack; DeLorenzo, Christine et al. (2004) Non-invasive assessment of radiation injury with electrical impedance spectroscopy. Phys Med Biol 49:665-83
Kerner, T E; Harto, A; Osterman, K S et al. (2001) An improved data acquisition method for electrical impedance tomography. Physiol Meas 22:31-8
Kerner, T E; Williams, D B; Osterman, K S et al. (2000) Electrical impedance imaging at multiple frequencies in phantoms. Physiol Meas 21:67-77
Hartov, A; Mazzarese, R A; Reiss, F R et al. (2000) A multichannel continuously selectable multifrequency electrical impedance spectroscopy measurement system. IEEE Trans Biomed Eng 47:49-58
Paulsen, K D; Osterman, K S; Hoopes, P J (1999) In vivo electrical impedance spectroscopic monitoring of the progression of radiation-induced tissue injury. Radiat Res 152:41-50
Osterman, K S; Paulsen, K D; Hoopes, P J (1999) Application of linear circuit models to impedance spectra in irradiated muscle. Ann N Y Acad Sci 873:21-9
Paulsen, K D; Jiang, H (1997) An enhanced electrical impedance imaging algorithm for hyperthermia applications. Int J Hyperthermia 13:459-80