DICOM2PHITS and PSFC4PHITS are user assistance programs for medical physics PHITS applications. DICOM2PHITS is a program to construct the voxel PHITS simulation geometry from patient CT DICOM image data by using a conversion table from CT number to material composition. PSFC4PHITS is a program to convert the IAEA phase-space file data to PHITS format to be used as a simulation source of PHITS. Both of the programs are useful for users who want to apply PHITS simulation to verification of the treatment planning of radiation therapy. We are now developing a program to convert dose distribution obtained by PHITS to DICOM RT-dose format. We also want to develop a program which is able to implement treatment information included in other DICOM files (RT-plan and RT-structure) as a future plan.