Experimental validation of Monte Carlo depth-dose calculations using radiochromic dye film dosimetry for a beta-gamma 153Sm radionuclide applied to the treatment of rheumatoid arthritis.

In this work we compare the Monte Carlo (MCNP4B) calculated beta-gamma depth-dose profile for a liquid 153Sm beta-gamma source used in radiation synovectomy with the experimental depth-dose distribution obtained using radiochromic dye film dosimetry. The calculated and experimental depth-dose distribution shows a very good agreement (within 5%) in the region where the dose deposition is dominated by the beta particle component (first 800 microm depth on tissue-equivalent material). The agreement worsens, reaching a maximum deviation of 15%, at depths close to the maximum range of the beta particles. Finally the agreement improves for the region where the gamma component accounts for one-third of the total absorbed dose (depths >1 mm). The possible contributions to these differences are discussed, as well as their relevance for the application of 153Sm in the treatment of rheumatoid arthritis.