When treating with electrons, what is your approach to skin collimation to reduce penumbra next to structures such as the eye?  

Skin surface shielding/collimation can be accomplished by a few methods. One is to create an impression of the patient and then conform thin sheets of lead/high density shielding material to this shape with an appropriate aperture for the target. This is time-consuming but preferable for small targe...

Custom lead mask on the surface. 2 cm margin as opposed to 1 cm with orthovoltage. Bolus thickness depending on the target and electron energy. I’ve told patients that if there is no surface collocation, find another doctor. 

There are also 3D printing methods to create tertiary collimation. Consult your physicist(s). We are able to use the CT sim images to "print out" tertiary collimation and custom bolus. 

My favorite way of dealing with "[electron] penumbra next to structures such as the eye" is to do a 3D electron plan in the treatment planning system (e.g. Eclipse). Penumbra is an "uncertainty"... until you model it in the way we're accustomed to modeling things i.e. doing 3D planning. Physicists h...