Assessment of thermal effects of interstitial laser phototherapy on mammary tumors using proton resonance frequency method.
ABSTRACT Laser immunotherapy (LIT) uses a synergistic approach to treat cancer systemically through local laser irradiation and immunological stimulation. Currently, LIT utilizes dye-assisted noninvasive laser irradiation to achieve selective photothermal interaction. However, LIT faces difficulties treating deeper tumors or tumors with heavily pigmented overlying skin. To circumvent these barriers, we use interstitial laser irradiation to induce the desired photothermal effects. The purpose of this study is to analyze the thermal effects of interstitial irradiation using proton resonance frequency (PRF). An 805-nm near-infrared laser with an interstitial cylindrical diffuser was used to treat rat mammary tumors. Different power settings (1.0, 1.25, and 1.5 W) were applied with an irradiation duration of 10 min. The temperature distributions of the treated tumors were measured by a 7 T magnetic resonance imager using PRF. We found that temperature distributions in tissue depended on both laser power and time settings, and that variance in tissue composition has a major influence in temperature elevation. The temperature elevations measured during interstitial laser irradiation by PRF and thermocouple were consistent, with some variations due to tissue composition and the positioning of the thermocouple's needle probes. Our results indicated that, for a tissue irradiation of 10 min, the elevation of rat tumor temperature ranged from 8 to 11°C for 1 W and 8 to 15°C for 1.5 W. This is the first time a 7 T magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. Our work provides a basic understanding of the photothermal interaction needed to control the thermal damage inside a tumor using interstitial laser treatment. Our work may lead to an optimal protocol for future cancer treatment using interstitial phototherapy in conjunction with immunotherapy.
Full-textDOI: · Available from: Nataliya Smith, Jun 07, 2015
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ABSTRACT: Photothermal therapy is an effective means to induce tumor cell death, since tumor tissue is more sensitive to temperature increases than normal tissue. Biological responses depend on tissue temperature; target tissue temperature needs to be precisely measured and controlled to achieve desired thermal effects. In this work, a unique photoacoustic (PA) sensor is proposed for temperature measurement during interstitial laser phototherapy. A continuous-wave laser light and a pulsed laser light, for photothermal irradiation and photoacoustic temperature measurement, respectively, were delivered to the target tissue through a fiber coupler. During laser irradiation, the PA amplitude was measured. The Grüneisen parameter and the bioheat equation were used to determine the temperature in strategic positions in the target tissue. Our results demonstrate that the interstitial PA amplitude is a linear function of temperature in the range of 22 to 55 °C, as confirmed by thermocouple measurement. Furthermore, by choosing appropriate laser parameters, the maximum temperature surrounding the active diffuse fiber tip in tissue can be controlled in the range of 41 to 55 °C. Thus, this sensor could potentially be used for fast, accurate, and convenient three-dimensional temperature measurement, and for real-time feedback and control of interstitial laser phototherapy in cancer treatment.Sensors 03/2015; 15(3):5583-5593. DOI:10.3390/s150305583 · 2.05 Impact Factor
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ABSTRACT: A novel, promising potential cancer vaccine strategy was proposed to use a two-injection procedure for solid tumors to prompt the immune system to identify and systemically eliminate the primary and metastatic cancers. The two-injection procedure consists of local photothermal application on a selected tumor intended to liberate whole cell tumor antigens, followed by a local injection of an immunoadjuvant that consists of a semi-synthetic functionalized glucosamine polymer, N-dihydro-galacto-chitosan (GC), which is intended to activate antigen presenting cells and facilitate an increased uptake of tumor antigens. This strategy is thus proposed as an in situ autologous cancer vaccine (inCVAX) that may activate antigen presenting cells and expose them to tumor antigens in situ, with the intention of inducing a systemic tumor specific T-cell response. Here, the development of inCVAX for the treatment of metastatic cancers in the past decades are systematically reviewed. The antitumor immune responses of local photothermal treatment and immunological stimulation with GC are also discussed. This treatment approach is also commonly referred to as laser immunotherapy (LIT). Copyright © 2015. Published by Elsevier Ireland Ltd.Cancer Letters 01/2015; 359(2). DOI:10.1016/j.canlet.2015.01.029 · 5.02 Impact Factor
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ABSTRACT: In this study, we proposed photoacoustic imaging to monitor the temperature increase during photothermal therapy, which was carried out by utilizing a continuous wave laser and photoabsorber-enhanced black ink with a absorption peak in the near-infrared optical range. A focusing photoacoustic imaging is interfaced with a nanosecond pulsed laser to image tissue-mimicking phantoms before and after laser irradiation. The results demonstrated that changes in the photoacoustic signal could reflect temperature changes in tissue. More importantly, photoacoustic signal could be used to determine the temperature at the boundary of photoabsorber-enhance tissue during photothermal irradiation. Thus, the photoacoustic imaging could potentially become an effective tool to guide photoabsorber-enhanced photothermal therapy.Proceedings of SPIE - The International Society for Optical Engineering 02/2013; DOI:10.1117/12.2001756 · 0.20 Impact Factor