Criteria for Verification and Replanning Based on the Adaptive Radiotherapy Protocol "Best for Adaptive Radiotherapy"...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Establishing clear criteria for adaptive radiotherapy (ART) patient selection and timing remains a challenge in image-guided radiotherapy (IGRT).
• Current decision-making for replanning lacks standardized guidelines, potentially leading to suboptimal treatment adjustments.

Purpose of the Study:

• To introduce and validate the Best for Adaptive Radiotherapy (B-ART) protocol for patient selection in ART.
• To identify anatomical and clinical predictors necessitating replanning in head and neck (HN) cancer patients undergoing helical tomotherapy (HT).

Main Methods:

• Retrospective analysis of 82 HN cancer patients treated with HT requiring replanning due to soft tissue changes observed on daily MVCT.
• Implementation of the B-ART protocol criteria: patients with >3 mm anatomical changes on 3-4 consecutive scans were considered for ART.
• Comparison of initial CT (iCT) and replanning CT (rCT) scan volumes for clinical target volumes (CTV1, CTV2), parotid glands (PG), and body contour (B-body).

Main Results:

• The primary reasons for replanning included PTV outside body contour (85.4%), PG shrinkage (84.1%), B-body deviations (84.1%), and setup deviations (48.8%).
• Significant mean volume reductions were observed in both right (20.9%) and left (20.5%) parotid glands (p < 0.001).
• Advanced stage disease (T3-T4), chemoradiation, increased weight loss, and oropharyngeal localization were significantly associated with the need for ART.

Conclusions:

• The B-ART protocol provides objective criteria to guide patient selection and timing for ART, reducing variability in decision-making.
• The protocol facilitates early detection and response to significant anatomical changes during radiotherapy.
• The findings highlight key predictors for ART, aiding in personalized treatment adjustments for HN cancer patients.