<prompt> In treatment of papillary carcinoma thyroid, radioiodine destroys the neoplastic cells predominantly byX-raysBeta raysGamma raysAlpha particles  <response>: RADIOACTIVE IODINE I131 THERAPY:I131 is an effective agent for delivering high radiation doses to the thyroid tissueIt emits mainly beta radiation 90, which penetrates only 0.5 mm of the tissue and thus allow therapeutic effects on the thyroid without any damage to the surrounding structures, particularly the parathyroids.Mechanism of Action:I131 emits beta particles and X-rays.Beta rays are utilized for their destructive effects on thyroid cells.X-rays are useful for tracer studies. 