### Abstract

We consider the general problem of laser pulse heating of a spherical dielectric particle embedded in a liquid. The discussed range of the problem parameters is typical for medical and biological applications. We focus on the case, when the heat diffusivity in the particle is of the same order of magnitude as that in the fluid. We perform quantitative analysis of the heat transfer equation based on interplay of four characteristic scales of the problem, namely the particle radius, the characteristic depth of light absorption in the material of the particle and the two heat diffusion lengths: in the particle and in the embedding liquid. A new quantitative characteristic of the laser action, that is the cooling time, describing the temporal scale of the cooling down of the particle after the laser pulse is over, is introduced and discussed. Simple analytical formulas for the temperature rise in the center of the particle and at its surface as well as for the cooling time are obtained. We show that at the appropriate choice of the problem parameters the cooling time may be by many orders of magnitude larger the laser pulse duration. It makes possible to minimize the undesirable damage of healthy tissues owing to the finite size of the laser beam and scattering of the laser radiation, simultaneously keeping the total hyperthermia period large enough to kill the pathogenic cells. An example of application of the developed approach to optimization of the therapeutic effect at the laser heating of particles for cancer therapy is presented.

Original language | English |
---|---|

Article number | 263677 |

Pages (from-to) | 2781-2788 |

Number of pages | 8 |

Journal | Biomedical Optics Express |

Volume | 7 |

Issue number | 7 |

DOIs | |

Publication status | Published - Jul 1 2016 |

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### All Science Journal Classification (ASJC) codes

- Biotechnology
- Atomic and Molecular Physics, and Optics

### Cite this

*Biomedical Optics Express*,

*7*(7), 2781-2788. [263677]. https://doi.org/10.1364/BOE.7.002781

**Laser heating of dielectric particles for medical and biological applications.** / Tribelsky, Michael I.; Fukumoto, Yasuhide.

Research output: Contribution to journal › Article

*Biomedical Optics Express*, vol. 7, no. 7, 263677, pp. 2781-2788. https://doi.org/10.1364/BOE.7.002781

}

TY - JOUR

T1 - Laser heating of dielectric particles for medical and biological applications

AU - Tribelsky, Michael I.

AU - Fukumoto, Yasuhide

PY - 2016/7/1

Y1 - 2016/7/1

N2 - We consider the general problem of laser pulse heating of a spherical dielectric particle embedded in a liquid. The discussed range of the problem parameters is typical for medical and biological applications. We focus on the case, when the heat diffusivity in the particle is of the same order of magnitude as that in the fluid. We perform quantitative analysis of the heat transfer equation based on interplay of four characteristic scales of the problem, namely the particle radius, the characteristic depth of light absorption in the material of the particle and the two heat diffusion lengths: in the particle and in the embedding liquid. A new quantitative characteristic of the laser action, that is the cooling time, describing the temporal scale of the cooling down of the particle after the laser pulse is over, is introduced and discussed. Simple analytical formulas for the temperature rise in the center of the particle and at its surface as well as for the cooling time are obtained. We show that at the appropriate choice of the problem parameters the cooling time may be by many orders of magnitude larger the laser pulse duration. It makes possible to minimize the undesirable damage of healthy tissues owing to the finite size of the laser beam and scattering of the laser radiation, simultaneously keeping the total hyperthermia period large enough to kill the pathogenic cells. An example of application of the developed approach to optimization of the therapeutic effect at the laser heating of particles for cancer therapy is presented.

AB - We consider the general problem of laser pulse heating of a spherical dielectric particle embedded in a liquid. The discussed range of the problem parameters is typical for medical and biological applications. We focus on the case, when the heat diffusivity in the particle is of the same order of magnitude as that in the fluid. We perform quantitative analysis of the heat transfer equation based on interplay of four characteristic scales of the problem, namely the particle radius, the characteristic depth of light absorption in the material of the particle and the two heat diffusion lengths: in the particle and in the embedding liquid. A new quantitative characteristic of the laser action, that is the cooling time, describing the temporal scale of the cooling down of the particle after the laser pulse is over, is introduced and discussed. Simple analytical formulas for the temperature rise in the center of the particle and at its surface as well as for the cooling time are obtained. We show that at the appropriate choice of the problem parameters the cooling time may be by many orders of magnitude larger the laser pulse duration. It makes possible to minimize the undesirable damage of healthy tissues owing to the finite size of the laser beam and scattering of the laser radiation, simultaneously keeping the total hyperthermia period large enough to kill the pathogenic cells. An example of application of the developed approach to optimization of the therapeutic effect at the laser heating of particles for cancer therapy is presented.

UR - http://www.scopus.com/inward/record.url?scp=84977079494&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84977079494&partnerID=8YFLogxK

U2 - 10.1364/BOE.7.002781

DO - 10.1364/BOE.7.002781

M3 - Article

AN - SCOPUS:84977079494

VL - 7

SP - 2781

EP - 2788

JO - Biomedical Optics Express

JF - Biomedical Optics Express

SN - 2156-7085

IS - 7

M1 - 263677

ER -