Palliative radiation therapy for bone tumors is widely implemented for variety of purposes. Among them, for treatment of vertebral compression fractures due to bone tumors, percutaneous vertebroplasty (PVP) and external beam radiation therapy after PVP are used. The contrast media mixed into bone cement are high atomic number materials. Moreover, dose calculations using Computed Tomography (CT) images may be inaccurate due to X-ray interactions and high density material employed in the commonly used Radiation Treatment Planning System (RTPS). The effect of contrast medium on dose distributions in radiotherapy of bone tumors after PVP is unknown. Toward this end, we investigated the depth dose in the phantom, which was configured to the water-equivalent solid phantom, and contrast medium was acquired by film measurement and calculation of the RTPS. As a result, very high dose enhancement occurred.Additionally, our dose calculation algorithm, which employed methods such as Monte Carlo, and installing information of object substances to the RTPS were required for accurate calculation of dose distribution. Such features are not included in commercially available RTPSs, and if materials of high atomic numbers, such as metal implants, were included in the radiation field, the hot spot may not be recognized in the RTPS. In the radiotherapy of bone tumors after PVP, we recommend the opposing portal irradiation than the single field irradiation to reduce dose enhancement due to the backscatter.