Biological effective dose (BED) distribution calculation is desirable for combining multiple treatments based on image sets at different times and/or with different fractionations, e.g., re-irradiation. In addition, the composite BED plan needs to be converted back to a physical dose plan in a common fractionation for plan evaluation and/or comparison. The purpose of this work is to develop a practical workflow to composite 3D BED plan and to convert it back to a physical dose plan.The workflow was developed using contouring software. The organ-specific radiobiological parameters (e.g., α/β, γ/α and dt) for different organs at risk (OAR) were obtained by fitting available clinical dose volume constraint data using a linear-quadratic-linear (LQ-L) model and were stored in the software. The BEDs in each voxel for two separate treatments were calculated using the LQ-L model for each OAR. By contour-based deformable image registration (DIR) algorithm in the software, the two images were registered to obtain a 3D composite BED. Using the rearranged LQ-L model in the software extension, the physical dose was calculated for a given fractionation scheme voxel by voxel from the 3D composite BED.The contouring software workflow along with the organ-specific BED parameters was implemented and successfully tested with two head and neck cancer re-irradiation cases. Case I was initially treated with 36 Gy in 6 fractions in 2017 and was re-irradiated with 35 Gy in 5 fractions in 2020. The case II had the first treatment of 70 Gy in 35 fractions in 2008 and the second treatment with 40 Gy in 5 fractions in 2020. The composite BED distributions calculated by the contouring software workflow were converted back to physical dose distributions with 2 Gy per fraction. The total physical doses received by the OARs after second treatments were all within acceptable clinical dose limits, consistent with the fact that no radiation related toxicity was reported for both patients. The obtained organ-specific parameters and the calculation results for these two cases are tabulated below.A practical workflow along with organ-specific radiobiological parameters was developed to generate BED composite plan and to convert it back into physical dose distribution. This study provides an additional tool to evaluate overall dose for each OAR in re-irradiation or iso-toxic adaptive radiation therapy.