Treatment Planning Protocols: A Method to Improve Consistency in IMRT Planning

Abstract

The Ottawa Hospital Cancer Centre (TOHCC) is a tertiary academic cancer center operating ten megavolt treatment units and treating approximately 4000 new patients per year. The treatment equipment includes 2 helical tomotherapy units (TomoTherapy HI-ART, TomoTherapy Inc., Madison, WI) and a high proportion of the more complex cases and clinical trials patients are treated with these units. The radiation therapists assigned to the tomotherapy units perform all treatment planning and treatment delivery. With this model, training in intensity-modulated radiation therapy (IMRT) treatment planning is required for each therapist assigned to the program. Although the therapists do not rotate frequently to other units, the training of new staff assigned to a tomotherapy unit is challenging. Tomotherapy is different from the other technology in the department, and the therapists assigned to these units have the additional role of treatment planning. The treatment planning process is labor-intensive and presents opportunities for error. During treatment planning, structures are classified into either tumor or sensitive structure settings. After settings are assigned, structures are prioritized on the basis of overlap between 2 or more structures of the same setting, referred to as overlap priority. Overlap priorities ensure that dose constraints and dose reporting are assigned to the appropriate structure volume, as outlined by the treatment planner. Setting the overlap priority is a source of error t TOHCC, especially for inexperienced planners. Expeience is important when selecting overlap priority and nitial optimization parameters to efficiently produce igh-quality treatment plans. This work describes a method to reduce treatment lanning time, standardize the planning process, and inimize the potential for errors, all imperative features f an efficient IMRT planning process for research trial ases.