Dose accumulation to assess the validity of treatment plans with reduced margins in radiotherapy of head and neck cancer.

Background And Purpose: Literature has reported reduced treatment toxicity in head-and-neck radiotherapy (HNRT) when reducing the planning target volume (PTV) margin from 5 to 3 mm but loco-regional control was not always preserved. This study used deformable image registration (DIR)-facilitated dose accumulation to assess clinical target volume (CTV) coverage in the presence of anatomical changes.

Materials And Methods: VMAT plans for 12 patients were optimized using 3 or 5 mm PTV and planning risk volume (PRV) margins.

Quantifying the dose accumulation uncertainty after deformable image registration in head-and-neck radiotherapy.

Background And Purpose: Deformable image registration (DIR) facilitated dose reconstruction and accumulation can be applied to assess delivered dose and verify the validity of the treatment plan during treatment. This retrospective study used in silico deformations based on clinically observed anatomical changes as ground truth to investigate the uncertainty of reconstructed and accumulated dose in head-and-neck radiotherapy (HNRT).

Materials And Methods: A planning CT (pCT), cone beam CT (CBCT) from week one of treatment and three later CBCTs were selected for 12 HNRT patients.

Monitoring anatomical changes of individual patients using statistical process control during head-and-neck radiotherapy.

Background And Purpose: Reduced toxicity while maintaining loco-regional control rates have been reported after reducing planning target volume (PTV) margins for head-and-neck radiotherapy (HNRT). In this context, quantifying anatomical changes to monitor patient treatment is preferred. This retrospective feasibility study investigated the application of deformable image registration (DIR) and Exponentially Weighted Moving Average (EWMA) Statistical Process Control (SPC) charts for this purpose.