Numerical Analysis of Cold Injury of Skin in Cryogen Spray Cooling for Dermatologic Laser Surgery

Li, Dong; He, Ya‐Ling; Wang, Guo. Xiang; Xiao, Jie; Liu, Yingwen

doi:10.1115/imece2007-43876

Cited by 6 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was found that spurt duration longer than 100 ms could result in epidermal injury acutely, and 500 ms spurt duration of CSC even could cause decreased fibroblast proliferation to dermis. Li et al [56,57] also simulated the cooling process and evaluated the potential cold injury of CSC with R134a, R407C, and R404A through a multiscale model, in which cold injury was recognized once cells were dehydrated or the ice formed intracellularly. They reported spurt duration causing cold injury were 3.3, 2.2, and 1.9 s for R134a, R407C, and R404A, respectively, which was much longer than that reported by Kao et al [54,55].…”

Section: Parametric Study On Heat Transfer Of Cscmentioning

confidence: 99%

The Fundamental and Application of Transient Flashing Spray Cooling in Laser Dermatology

Zhou¹,

Chen²

2019

Advanced Cooling Technologies and Applications

View full text Add to dashboard Cite

Cryogen spray cooling (CSC) has been successfully implemented in laser dermatology such as the treatment of port wine stain. It can protect epidermis from irreversible thermal injuries and increase laser energy, leading to the improvement in therapeutic outcomes. Different from traditional steady spray cooling, CSC is highly transient with short spurt duration (several tens of milliseconds). Besides, CSC can achieve flashing atomization and fine droplets with simple structure nozzles by rapid release of superheat. In this chapter, the mechanism of CSC flashing spray, spray and thermal characteristics of droplets, the measurement method of transient temperature and algorithms for heat flux estimation, and the dynamic surface heat transfer and its relation with spray characteristics are fully discussed. Finally, the heat transfer enhancement of CSC is introduced including alternative cryogens, new nozzles, and hypobaric pressure method to increase the cooling ability, which is essential to improve therapeutic outcome, especially for darkly pigmented human skin.

show abstract

Section: Parametric Study On Heat Transfer Of Cscmentioning

confidence: 99%

The Fundamental and Application of Transient Flashing Spray Cooling in Laser Dermatology

Zhou¹,

Chen²

2019

Advanced Cooling Technologies and Applications

View full text Add to dashboard Cite

show abstract

“…The convection heat transfer coefficients, h a , represents normal cooling after CSC. The convective heat transfer coefficient, h c , during CSC, is evaluated from the following generalized correlation [19,20]:…”

Section: T Z H T T R T T H T R T Tmentioning

confidence: 99%

“…It is noticed that above relation includes two free parameters, i.e., t max and h o,max , which have to be experimentally determined and are available only for R134a [19,20]. In this paper, we assume that the relation is applicable to other cryogens like R407c and R404a, as suggested from our recent experiments [32].…”

Section: T Z H T T R T T H T R T Tmentioning

confidence: 99%

“…Jia et al [18] have even used the measured heat flux from their experiments in their model. Recently, based on the experimental data, the present authors have introduced a universal relation of dynamic varying heat transfer coefficient during cryogen spray [19,20]. This relation includes both the spatial and temporal variation of h during the short-pulsed spray cooling process.…”

mentioning

confidence: 99%

See 1 more Smart Citation

A new model of selective photothermolysis to aid laser treatment of port wine stains

Liu

Wang

et al. 2013

Chin. Sci. Bull.

Self Cite

View full text Add to dashboard Cite

Pulsed dye lasers equipped with cryogen spray cooling (CSC) are now widely used to treat vascular malformation such as port wine stains (PWSs). This paper presents a new integrated model that can quantitatively simulate the cooling of the skin and the heating of the targeted blood vessels in PWSs during laser treatment. The new model is based on the classical homogeneous multi-layer skin model that treats PWS-containing dermis as a mixture of dermal tissue and homogeneously distributed blood. Light propagation in skin and PWSs is simulated by a Monte-Carlo method, which provides accurate description of the light scattering and absorption in the skin. Thermal response of a targeted vessel in the new model is then obtained from the thermal analysis of a Krogh-unit that consists of the vessel and the surrounding dermal tissues and is buried in PWSs. The results from the multi-layer skin model provide appropriate laser influence input as well as the initial thermal condition for the micro-model of the Krogh-unit. A general dynamic relation is also introduced on the surface of skin to quantify the convective cooling of CSC. The model is then applied to dye-laser treatment (wavelength of 585 nm) of PWSs with CSC. Numerical results demonstrate that the present model is able to quantify thermal response of a deeply buried blood vessel in PWSs as a discrete blood vessel does, with a more realistically estimate of the sheltering effect of the dermal tissue (scattering) and blood vessels (absorption) in front of the targeted vessel. To understand the poor response of PWSs in clinic, the thermal characteristics of a targeted vessel was simulated under various conditions. The effects of two morphological parameters, the vessel diameter and the burying depth of the vessel, are then systematically investigated under various pulse durations and fluences of laser. A threshold fluence for given vessel diameter and depth is then estimated quantitatively under the condition of the optimal laser pulse duration. The results indicate that significant high threshold fluence is needed for large vessels buried deeply in the dermis, explaining the physics of the difficulty in clinic of complete clearance of PWSs. The results provide guidance to the clinic selection of the laser pulse duration and laser energy fluence for given PWSs.

show abstract

“…Due to the limited experimental data, the early models of laser PWS always employed a constant heat transfer coefficient to quantify the short-pulsed cooling process (Aguilar et al, 2002;Tunnell et al, 2003;Pfefer et al, 2000;Majaron et al, 2001;Verkruysse et al, 2000). Recent experiments revealed that a strong dynamic variation in the heat transfer coefficient existed in CSC (Li et al, 2007(Li et al, , 2014Aguilar et al, 2003), which will lead to an inaccurate prediction on the cooling effect of CSC in laser treatment of PWS by the previous models. A quantitative correlation has been developed recently by present authors to describe dynamic varying heat transfer coefficient during cryogen spray (Li et al, 2007(Li et al, , 2014.…”

mentioning

confidence: 99%

Computational investigation on thermal responses of blood vessels during laser treatment of port wine stain

Liu

Chen

Wang

2016

Int Jnl of Num Meth for HFF

Self Cite

View full text Add to dashboard Cite

Purpose – The purpose of this paper is to present a numerical analysis of the laser surgery of port wine stain (PWS) with cryogen spray cooling to compare the treatment effect between pulse dye laser and Nd:YAG laser, explain the incomplete clear of the lesion and optimize the laser parameter. Design/methodology/approach – The complex structure of skin and PWS is simplified to a multi-layer skin model that consists of top epidermal layer and underneath dermis layer embedded with discrete blood vessels. The cooling effect of cryogen spray before laser firing is quantified by a general correlation obtained recently from the experimental data. The light distribution is modeled by the Monte Carlo method. The heat transfer in skin tissue is calculated by Pennes bioheat transfer model. The thermal damage of blood vessel is quantified by the Arrhenius damage integral. Findings – For the vessel size studied (10-120 µm), pulse duration is recommended shorter than 6 ms. Large and deeply buried vessels, which may survive from 595 nm laser irradiation, can be coagulated by 1,064 nm laser due to its deep light penetration depth in skin. Furthermore, a desired uniform heating within the large vessel lumen can be achieved by 1,064 nm laser whereas 595 nm laser produce non-uniform heating. Originality/value – The possible reason for the poor responding and incomplete clearance lesions is clarified. Laser wavelength and pulse duration are suggested to improve the clinical results.

show abstract

Numerical Analysis of Cold Injury of Skin in Cryogen Spray Cooling for Dermatologic Laser Surgery

Cited by 6 publications

References 0 publications

The Fundamental and Application of Transient Flashing Spray Cooling in Laser Dermatology

The Fundamental and Application of Transient Flashing Spray Cooling in Laser Dermatology

A new model of selective photothermolysis to aid laser treatment of port wine stains

Computational investigation on thermal responses of blood vessels during laser treatment of port wine stain

Contact Info

Product

Resources

About