RapidArc dynamic versus RapidArc: A multi anatomical-site dosimetric evaluation

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment Technology

Background:

• Conventional RapidArc (RA) VMAT delivery faces challenges in optimal organ-at-risk (OAR) sparing for complex cancer cases.
• RapidArc Dynamic (RAD) is a next-generation VMAT technique featuring dynamic collimator rotation, static fields, and an advanced optimizer for enhanced dose modulation.

Purpose of the Study:

• To compare the dosimetric outcomes, specifically OAR sparing and target coverage, between conventional RA and RAD across diverse anatomical sites.
• To evaluate the potential of RAD to overcome limitations of RA in complex treatment scenarios.

Main Methods:

• Retrospective analysis of 40 cancer patients (breast, lung SBRT, prostate, head and neck), with each case replanned using both RA and RAD.
• Dosimetric evaluation using dose-volume histograms (DVH) and statistical comparison of target coverage and OAR sparing parameters.

Main Results:

• RAD demonstrated equivalent target coverage compared to RA across all studied anatomical sites.
• Significant improvements in OAR sparing were observed with RAD, including reduced doses to the heart, lungs, rectum, bladder, spinal cord, parotids, and cochleae.
• RAD also showed improved dose conformity in lung SBRT cases.

Conclusions:

• RapidArc Dynamic (RAD) provides superior OAR sparing and enhanced dose conformity compared to conventional RapidArc (RA), while maintaining target coverage.
• The findings support the clinical adoption of RAD, especially for anatomically complex treatments requiring high precision.
• Further prospective research is recommended to validate the long-term clinical benefits of RAD.