Evaluation of CBCT based dose calculation in the thorax and pelvis using two generic algorithms

Area of Science:

• Medical Physics
• Radiotherapy Physics

Background:

• Cone-beam CT (CBCT) is widely used in image-guided radiotherapy.
• Accurate dose calculation is crucial for effective radiotherapy planning and delivery.

Purpose of the Study:

• To evaluate the dosimetric performance of two algorithms: corrected CBCT (corrCBCT) and virtual CT (vCT).
• To assess the suitability of these algorithms for adaptive radiotherapy workflows.

Main Methods:

• Sixty patients with breast, lung, prostate, and anal/rectal cancer were included.
• Clinical treatment plans were recalculated on corrCBCT, vCT, and reference CT (refCT).
• Dosimetric comparison was performed using gamma analysis and dose metrics (D98%, D50%, D2%).

Main Results:

• Both corrCBCT and vCT demonstrated high dosimetric accuracy with gamma pass rates >98% for most patients.
• Equivalence of dose metrics within ±1 Gy was observed across all patient groups.
• Pelvic patients showed equivalence within ±1% of refCT dose; thoracic patients showed equivalence within ±2.5% for most metrics.

Conclusions:

• corrCBCT and vCT images exhibit excellent dosimetric agreement with refCT.
• These imaging techniques hold significant potential for enhancing adaptive radiotherapy workflows.