Influence of pulse duration on frequency pattern of temperature variations in a phantom with Gold-gold sulfide particles during laser irradiation

摘要

Hyperthermia is an adjuvant cancer treatment in which the cancerous tissue is heated to a high temperature (up to 45°C) and expedites the process of cancer cells destruction. This modality is applied in combination with other treatments such as chemotherapy and radiation therapy. Moreover, hyperthermia sensitizes cancer cells to radiation or other treatment approaches. On the other hand, nanotechnology utilizes the engineered functional systems at nano scale and currently metal nanoparticles play a significant role in medicine. Among these, gold-gold sulfide nanoparticles (GGS-NPs)-assisted photothermal therapy has emerged as an efficient manner for selective killing of cancer cells. The phantom was consisted of two parts; the inner part simulates a tumor with 20 and 9 mm in height and diameter, respectively and the outer part simulates tumor's neighbor tissues. The phantom was illuminated by a millisecond pulsed diode laser (800nm) in the presence and absence of GGS-NPs into the simulated tumor. The temperature variations pattern was recorded by a digital thermometer (Waterproof super-fast needle probe, K Type, Testo 735-2). The sensors diameter located in certain situations into the simulated tumor was 1.4 mm. The Wigner-Ville analysis has been used to study frequency pattern of temperature signals into mentioned optical gel phantom during laser irradiating at one fluence and three pulse durations. By estimating instantaneous frequencies of temperature signals induced in different parameters of laser irradiation, the best pulse duration can be selected for Hyperthermia application. Our findings have anticipated that GGS synergism with laser pulses can be utilized to induce an increased temperature in a target region and it was estimated the pulsed laser irradiation at fluence of 40 mJ/cm-2 and 30 ms duration as the best condition in order to provide a proper profile in temperature variations of tumor.