First don't stress.
When you approach the checkpoint ask to speak to a supervisor.
Explain that you would like a private screening due to a medical issue.
Explain the issue to the officer. Most likely your scalp area will be hand wanded. If the wand doesn't beep, all done. Try to avoid metal (bobby pins, etc) in your hair do. An alarm MAY lead to a limited pat down as will an extereme Bee hive or similar style.
Keep smiling. The lower the ambient stress level, the better it will be for all.
Enjoy the flight! well try.

PS:
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