How deep into the skin does the IG-SRT radiation go?

IG-SRT uses superficial X-rays that penetrate only a short distance – approximately 3 to 5 millimeters deep into the tissue. This depth is roughly the thickness of the skin (epidermis and dermis). It’s enough to treat skin cancers that reside in those layers, but it does not reach underlying fat, muscle, or internal organs. The exact penetration can be adjusted slightly by the energy setting on the machine, but by design, it’s meant for lesions at or near the skin surface. For reference, 5 mm is about the depth of a grain of rice. Most basal and squamous cell carcinomas are within that realm. This shallow penetration is a safety feature – it ensures that the radiation is not unnecessarily reaching tissues beneath the skin. So, you can visualize it as treating a “slice” of your skin where the cancer is, and nothing below that slice. If a tumor were, say, 8 mm deep (which is uncommon for these skin cancers without involving other structures), the doctor might consider other options or carefully plan the treatment. But for the typical cases, IG-SRT’s penetration is more than sufficient to cover the tumor while protecting deeper tissues.