Abstarct: In this study, to investigate the effect of aluminum oxide, copper, and silver nanoparticles on the dose buildup factor, MAGAS and PAGAS polymer gels were used as nanoparticle carriers. The source of gamma rays is a cesium source. The detector used to measure the dose buildup factor is NaI(TL). In radiation therapy, the use of lead shields, which are heavy, inflexible, and toxic, will cause problems. Therefore, the use of lightweight, flexible, and non-toxic shields in radiation therapy is essential. Composites can be used to achieve this goal. A composite, in its simplest form, consists of two components: a matrix and a reinforcement. To make the shield light and flexible, a material that is light and flexible can be used as a matrix, and to make the shield better attenuate the rays, nanoparticles that better attenuate the rays after they hit the shield can be used as an reinforcement. A polymer gel containing nanoparticles is a composite in which the polymer gel is the matrix and the nanoparticles are the reinforcement. Given that the goal of the radiation therapy process is to destroy cancer cells by irradiation the cancerous tissue, and on the other hand, some of this radiation hits the healthy tissues surrounding the cancerous tissue, and this action destroys the healthy tissues surrounding the cancerous tissue, we cannot continue radiation therapy as much as we want. In order to cause the most destruction in cancer cells with the least radiation exposure and the least damage to healthy tissues surrounding the cancer tissue, we inject nanoparticles into the cancer tissues. According to the results of this research, it is observed that the amount of radiation energy absorption in polymer gel containing silver nanoparticles is greater than that in polymer gel containing copper nanoparticles, and the amount of radiation energy absorption in polymer gel containing copper nanoparticles is greater than that in polymer gel containing aluminum oxide nanoparticles. To make a suitable shield (light, flexible, and non-toxic), a light, flexible, and non-toxic material with uniformly distributed silver nanoparticles can be used because the presence of silver nanoparticles increases the absorption of radiation energy in this material, and increased radiation energy absorption causes further attenuation of the radiation after it hits this material. Silver nanoparticles can also be used in radiation therapy because the presence of silver nanoparticles in cancerous tissue causes further destruction of the cancerous tissue due to increased absorption of radiation energy.