Ultrasound irradiation to a certain site of the body affects the efficacy of drug delivery through changes in the permeability of cell membrane. Temperature increase in irradiated area may be affected by frequency, intensity, period of ultrasound, and blood perfusion. The aim of present study is to use computer simulation and offer an appropriate model for thermal distribution profile in prostate tumor. Moreover, computer model was validated by in vivo experiments. Method. Computer simulation was performed with COMSOL software. Experiments were carried out on prostate tumor induced in nude mice (DU145 cell line originated from human prostate cancer) at frequency of 3？MHz and intensities of 0.3, 0.5, and 1？w/cm2 for 300 seconds. Results. Computer simulations showed a temperature rise of the tumor for the applied intensities of 0.3, 0.5 and 1？w/cm2 of 0.8, 0.9, and 1.1°C, respectively. The experimental data carried out at the same frequency demonstrated that temperature increase was 0.5, 0.9, and 1.4°C for the above intensities. It was noticed that temperature rise was very sharp for the first few seconds of ultrasound irradiation and then increased moderately. Conclusion. Obtained data holds great promise to develop a model which is able to predict temperature distribution profile in vivo condition. 1. Introduction Prostate cancer is one of the most common malignant cancers in men [1]. There are a variety of treatments for prostate cancer among which chemotherapy is one of the most important methods. Application of chemotherapy for treatment of cancer is associated with some limitations. Today, drug targeting towards cancer cells and increasing drug concentration inside the tumor are the greatest purposes of researchers because systematic distribution of the anticancer agent may induce damages in normal tissue [2, 3]. Application of ultrasound is one of the basic techniques which has been used to increase the efficiency of drug delivery [4]. Traditionally, ultrasound waves have been used either for ultrasound hyperthermia or physiotherapy to warm the tissue or to kill cancerous cells [5]. Due to the ability of deep penetration into the living tissues, application of ultrasound wave has recently become an interesting area in noninvasive treatment and diagnostic medicine [6]. Ultrasound wave can deliver mechanical energy into the desired area inside the body. Absorption of ultrasound mechanical energy can increase tissue temperature to a relatively high value which may be used in therapy [7]. In drug delivery, ultrasound waves vibrate drug carriers and
References
[1]
A. Blana, B. Walter, S. Rogenhofer, and W. F. Wieland, “High-intensity focused ultrasound for the treatment of localized prostate cancer: 5-year experience,” Urology, vol. 63, no. 2, pp. 297–300, 2003.
[2]
M. A. Moses, H. Brem, and R. Langer, “Advancing the field of drug delivery: taking aim at cancer,” Cancer Cell, vol. 4, no. 5, pp. 337–341, 2003.
[3]
Z. Liu, K. Chen, C. Davis et al., “Drug delivery with carbon nanotubes for in vivo cancer treatment,” Cancer Research, vol. 68, no. 16, pp. 6652–6660, 2008.
[4]
I. V. Larina, B. M. Evers, T. V. Ashitkov, C. Bartels, K. V. Larin, and R. O. Esenaliev, “Enhancement of drug delivery in tumors by using interaction of nanoparticles with ultrasound radiation,” Technology in Cancer Research and Treatment, vol. 4, no. 2, pp. 217–226, 2005.
[5]
O. M. Hassan, N. S. D. Hassan, and Y. M. Kadah, “Modeling of ultrasound hyperthermia treatment of breast tumors,” in Proceedings of the 26th National Radio Science Conference (NRSC '09), March 2009.
[6]
K. P. Curra, P. D. Mourad, V. A. Khokhlova, R. O. Cleveland, and L. A. Crum, “Numerical simulations of heating patterns and tissue temperature response due to high-intensity focused ultrasound,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 47, no. 4, pp. 1077–1089, 2000.
[7]
W. G. Pitt, G. Husseini, and B. J. Staples, “Ultrasonic drug delivery: a general review,” Expert Opinion on Drug Delivery, vol. 1, no. 1, pp. 37–56, 2004.
[8]
S. Humbert, T. Bettinger, F. Yan, and R. H. Guy, “Plasma membrane poration induced by ultrasound exposure: implication for drug delivery,” Journal of Controlled Release, vol. 104, no. 1, pp. 213–222, 2005.
[9]
R. J. Zemp, J. Tavakkoli, and R. S. C. Cobbold, “Modeling of nonlinear ultrasound propagation in tissue from array transducers,” Journal of the Acoustical Society of America, vol. 113, no. 1, pp. 139–152, 2003.
[10]
S. Ginter, “Numerical simulation of ultrasound-thermotherapy combining nonlinear wave propagation with broadband soft-tissue absorption,” Ultrasonics, vol. 37, no. 10, pp. 693–696, 2000.
[11]
J. Tavakkoli, D. Cathignol, and R. Souchon, “Modeling of pulsed finite-amplitude focused sound beams in time domain,” Journal of the Acoustical Society of America, vol. 104, no. 4, pp. 2061–2072, 1998.
[12]
H. H. Pennes, “Analysis of tissue and arterial blood temperatures in the resting human forearm,” Applied Physiology, vol. 85, no. 1, pp. 5–34, 1998.
[13]
W. Shen and J. Zhang, “Modeling and numerical simulation of bioheat transfer and biomechanics in soft tissue,” Mathematical and Computer Modelling, vol. 41, no. 11-12, pp. 1251–1265, 2005.
[14]
J. W. Durkee and P. P. Antich, “Exact solutions to the multi-region time-dependent bioheat equation with transient heat sources and boundary conditions,” Physics in Medicine and Biology, vol. 36, no. 3, pp. 345–368, 1991.
[15]
D. Orel and J. Rozman, “A computer simulation of ultrasound thermal bio-effect in embryonic models,” Radioengineering, vol. 12, pp. 26–30, 2003.
M. Pernot, J. Porquet, C. Olive, F. Vignon, D. Cassereau, and J. Aubry, “3D finite differences simulation of coupled acoustic wave and bio-heat equations: skull heating prediction for non invasive hifu therapy,” in Proceedings of the World Congress on Ultrasonics, Paris, France, September 2003.
[18]
M. Jankun, T. Kelly, A. Zaim et al., “Computer model for cryosurgery of the prostate,” Computer Aided Surgery, vol. 4, pp. 193–199, 1999.
[19]
A. Trakic, F. Liu, and S. Crozier, “Transient temperature rise in a mouse due to low-frequency regional hyperthermia,” Physics in Medicine and Biology, vol. 51, no. 7, pp. 1673–1691, 2006.
[20]
P. N. T. Wells, Biomedical Ultrasonic, Academic Press, London, UK, 1977.
[21]
W. Hendee and E. Riteno, Medical Imaging Physics, chapter 19, Wiley, New York, NY, USA, 4th edition, 2002.
[22]
L. Curiel, F. Chavrier, B. Gignoux, S. Pichardo, S. Chesnais, and J. Y. Chapelon, “Experimental evaluation of lesion prediction modelling in the presence of cavitation bubbles: intended for high-intensity focused ultrasound prostate treatment,” Medical and Biological Engineering and Computing, vol. 42, no. 1, pp. 44–54, 2004.
[23]
R. Souchon, G. Bouchoux, E. Maciejko et al., “Monitoring the formation of thermal lesions with heat-induced echo-strain imaging: a feasibility study,” Ultrasound in Medicine and Biology, vol. 31, no. 2, pp. 251–259, 2005.
[24]
M. B. Shiran, M. Motevalian, R. Ravanfar, and S. Bohlooli, “The effect of bubble surface charge on phonophoresis: implication in transdermal piroxicam delivery,” Iranian Journal of Pharmacology and Therapeutics, vol. 7, no. 1, pp. 15–19, 2008.
