Abstract
Laser propagation through a turbid rat dura mater membrane is shown to be controllable with a wavefront modulation technique. The scattered light field can be refocused into a target area behind the rat dura mater membrane with a 110 times intensity enhancement using a spatial light modulator. The efficient laser intensity concentration system is demonstrated to imitate the phototherapy for human brain tumors. The power density in the target area is enhanced more than 200 times compared with the input power density on the dura mater membrane, thus allowing continued irradiation concentration to the deep lesion without damage to the dura mater. Multibeam inputs along different directions, or at different positions, can be guided to focus to the same spot behind the membrane, hence providing a similar gamma knife function in optical spectral range. Moreover, both the polarization and the phase of the input field can be recovered in the target area, allowing coherent field superposition in comparison with the linear intensity superposition for the gamma knife.
Highlights
Among successful surgery, radiotherapy, and chemotherapy technologies, phototherapy is regarded as a promising therapeutic technique as it has a number of distinct advantages including minimal invasiveness, lower systemic toxicity, selective tumor destruction and function preservation [1, 2]
photothermal therapy (PTT) uses optical absorbing agents to effectively convert photon energy into heat to increase the local temperature near the tumor region [3, 4], while photodynamic therapy (PDT) relies on cytotoxic singlet oxygen or reactive oxygen species from the photochemical reactions to induce tumor cell necrosis and/or apoptosis [5,6,7,8]
Vellekoop et al demonstrated a wavefront shaping technique which can focus the coherent light through disordered scattering media by using a spatial light modulator (SLM)
Summary
Radiotherapy, and chemotherapy technologies, phototherapy is regarded as a promising therapeutic technique as it has a number of distinct advantages including minimal invasiveness, lower systemic toxicity, selective tumor destruction and function preservation [1, 2]. In this article, focusing of light field through a turbid biological membrane (rat dura mater) is studied and the possibility of applying this technique to phototherapy for brain tumor is discussed. The experiment result shows a more than 200 times enhancement on power density in the target area compared with the input power density on the dura mater membrane, demonstrating the potential to improve the therapeutic efficacy of phototherapy while the effect of undesirable damage during laser delivery can be minimized. Light field concentration through a scattering biological tissue with wavefront shaping technique In this experiment, the scattering biological tissue is a rat dura mater. The result shows a 200.7 times enhancement (Table 1) This experiment demonstrates the possibility to avoid dura mater damage while the tumor behind it is experiencing a higher light fluence while increase the laser power. It shows the possibility to evaluate tumor cell necrosis and the efficacy of phototherapy
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