PO-0896: Treatment planning training for a large group in geographically spread centres

I. Kristensen, C. Vallhagen Dahlgren, H. Nyström
2013 Radiotherapy and Oncology  
Purpose/Objective: The purpose was to design and implement a comprehensive computerised calculation program to execute radiation-shielding evaluations for radiotherapy. The program addresses both individual and collective contributing factors that are intrinsic to shielding calculations e.g. building construction, treatment equipment and delivery techniques, workload and occupancy. It incorporates modern and emerging novel treatment delivery techniques and the resulting overall effects on
more » ... ion protection required. The secondary aim was to verify the shielding program by applying it to existing bunkers where measurements of photon and neutron doserate were made and to identify its advantages for modelling future radiotherapy bunkers. Materials and Methods: The calculation methods used to establish the photon and associated neutron dose rates employ the theoretical approach from the NCRP Report 151, and the IAEA Safety Report No. 47, among others. The advantage of including new treatment techniques (extra-cranial stereotactic and ablative RT,VMAT, FFF, robotic radio-surgery) and newly available constructional materials improves the usefulness of the program for any radiotherapy centre. The program can evaluate existing bunkers for changes in workload, treatment technique or delivery. It contains all variables to enable modelling of a new build using concrete,high-density materials and layered materials. Calculations using actual workload compared to 'worst -case' scenarios and the consequences on construction costs were evaluated. The contributions of photon, neutron scatter and neutron capture gamma rays were investigated with differing maze geometries. Special topics such as skyshine and ozone production were included too. The program includes all necessary TVLs and other intrinsic data, for modelling the spectrum of nominal photon energies clinically available, including flattened and flattening-filter-free (FFF) beam data. Results: The program's logic and accuracy was successfully validated by comparison to literature and using measurements taken at two sites with different bunker designs. The program was used to calculate potential shielding changes to an existing bunker due to increasing the beam energy. The results showed adequate shielding except at the maze entrance. The impact of actual workloads versus theorised workload was also investigated. There was a 10-20% reduction in shielding when the workload theorised in 2003 was compared to actual 2012 workload for three bunkers, which could reduce the building costs by 10%. Conclusions: A comprehensive calculation program for bunker shielding was developed to include contemporary and emerging treatment methods. Its accuracy and functionality were proven in the case studies. It is more functional and manageable than previous programs used at the institution.
doi:10.1016/s0167-8140(15)33202-3 fatcat:rvwllpdvcnafvlgkxfpcohml7u