An agent based model of laser hair removal

Agent Based Model of Laser Hair Removal

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Click 'Setup' and 'Go' keys below. The laser will be administered if 'give laser' switch is on.

created with NetLogo

WHAT IS IT?

Demonstration video

Laser hair removal (LHR) is a popular cosmetic dermatology procedure. However LHR is slow and expensive. Standardization is extremely complicated because of the difficulties in tracking and the long time period required for LHR. Though several mathematical models have been proposed, none is simple enough to be used as a patient education tool. This is an attempt at visually modelling LHR using the ‘Agent Based Modelling Method’. Experimental parameters are used wherever possible.

HOW IT WORKS

The model assigns individual hairs as independent oscillators randomly distributed over the anagen and telogen phase. Since the percentage of catagen hairs is small compared to the other two, it is not included in the model.
After each laser session, the chance of injury to hair and skin is calculated. It is further segregated as chance for

Injury to melanocyte
Thinning of hair
Anagen to Telogen Conversion
Permanent destruction

Please refer to the publication below for further details.

HOW TO USE IT

Clicking on setup will initialise the system with the set parameters. The visual interface is 1 cm2 of skin surface area. The grey hairs are in anagen and the yellow ones are in telogen. If the ‘give-laser’ switch is turned on the set number of laser sessions will be administered. Damaged hair will appear as red. If the background becomes red an uncommon side effect (pigmentation, crusting or scarring) has occurred.

THINGS TO NOTICE

The “Hirsutism Index” is calculated according to the following formula.
(5 * count visible hairs) + (3 * mean [hair-diameter] of hairs) + (2 * mean [hair-pigmentation] of hairs) + (mean [hair-length - hair-depth] of hairs)
The % improvement in “Hirsutism Index” is also displayed in the monitor marked ‘improvement %’.

THINGS TO TRY

The chance of hair and skin injury is also displayed. Parameters should be adjusted so that hair injury is maximised and skin injury is minimised.

EXTENDING THE MODEL

This model can be further extended by including less frequently encountered phenomena like paradoxical stimulation and phase synchronization. Besides catagen stage can be included in the model along with pulse duration.

NETLOGO FEATURES

ABM has been used for the study of complex systems in several fields including immunology. The intrinsic modular nature of ABM helps in representing a complex system like perturbations of hair growth cycle following the administration of an external agent like laser. Besides the visual interface provided by the NetLogo implementation of ABM makes the simulation easy to use and understand.

RELATED MODELS

Refer to the publication

CREDITS AND REFERENCES

The model is prepared by Dr Bell Raj Eapen and is available from my homepage http://www.gulfdoctor.net/model/lhr.htm

Please cite the following publication if you extend the model or use it for related projects.

Eapen BR. Agent-based model of laser hair removal: A treatment optimization and patient education tool. Indian J Dermatol Venereol Leprol. 2009 July-Aug;75(4):383-87. [Full Text] [Pubmed]

Read this non technical article about this model in associated content.