A shielding device includes two elongated, parallel tubes joined at a distal portion, and a shield at least one of removably and slidably situated at the distal portion. An assembly includes an applicator configured for a treatment site, an assembly block attached to the applicator, at least one rotary unit configured to be rotatably received in the assembly block, and at least one shielding device that is configured to be movably received in a respective rotary unit. A method of using the shielding device with an applicator includes inserting the distal portion of the shielding device to a treatment site, and adjusting a position of the distal portion relative to a distal end of the applicator.