Hi All,
When you buy an UVB-NB hand held (usually a 9w bulb) , you have to be aware of:
1- Despite its a 9 watt bulb, it irradiates only 1.16 miliwatts of UVB-NB, per square centimeter, at 5 cm far (2 inches).
2- So, you you expose the patch for 60 seconds, you will transfer 60 x 1.15 mw = 70 milijoules.
3- 70 milijoules will be the transfered (delivered) energy.
4- If you use a 18w (2 x 9w) hand held, it irradiates only 2 miliwatts of UVB-NB, per square centimeter, at 5cm far (2 inches).
5- So, you you expose the patch for 60 seconds, you will transfer 60 x 2 mw = 120 milijoules.
6- 120 milijoules will be the transfered (delivered) energy.
7- So, before using any UVB-NB hand held, check with your doctor the right protocol. Doctors must tell you how much energy has to be transffered to each patch. So you have to adjust the exposure time based on the formula: Energy = UVB-NB Power x Time
Power will vary with your device as mentioned above.
Don't get burned!
Replies
Thanks for sharing Flavio...For those who just buy NB UVB lamps since there are different lamps ..start by few secondes and inncrease gradually until you get pink and hold that time...dont get burn red is burning sign.
Dont use uvb for long period... use it by doctors supervison at the begning.
Hiya how long should it be used for, shouldn't you stop using it when some colour comes back?
If you reach full re-pigmentation, replaces it for sun bath before 9AM and after 5PM.
Thankyou:)
recently i fond some case history of vitiligo patient who take puva or nb-uva and note that if you sudden close or quit from puva or nb-uva after take it long time then white spot are really faster grow up. i saw that result in more then 50% of case history,anybody know something about that tell me.
Rocky, I really don't think UVB-NB can cause it. Specially if you do low dosages 3x a week.
Send the link so that we can try to understand it better.
I have a 9w bulb.
What should the distance be when i use the handheld UVB machine for back of my hands and palm hand ?
The closer it is, the more energy is transferred. You have to know how much energy each patch needs.
For example: If you want to transfer 1J (1000mJ) to your hand, if you keep the 9w bulb at 5cm (2") far, it will provide 1,15mw (per cm2). So, 1000mJ / 1,15 mw = 870 seconds (14,5 minutes).
So, the first thing to know is the UVB-NB exposure protocol. It means, how much energy needs to be transferred to each patch. Doctors should be able to tell you, but most of them don't know.
The other way to do it, is trial / error approach, that means: you start with 30 second exposure time at 5cm (2") far and wait 12 hours to see if the patch has got pink. If so, keep this time. If not, increase 15 seconds and try again. I don't like this approach, since you eventually get burned.