Accelerated large volume irradiation with dynamic Jaw/Dynamic Couch Helical Tomotherapy

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Helical Tomotherapy (HT) is utilized for large and complex target volumes in radiotherapy.
• Next-generation Dynamic Jaw/Dynamic Couch (DJDC) HT delivery aims to accelerate treatments and minimize organ at risk (OAR) exposure through a reduced dose penumbra.

Purpose of the Study:

• To compare the efficacy of Regular HT (Reg) with different field widths (2.5 cm and 5.0 cm) against DJDC HT (5.0 cm maximum field width).
• To evaluate target coverage, conformity, integral dose, OAR exposure, and treatment time in challenging clinical scenarios: Hemithoracic Irradiation, Whole Abdominal Irradiation (WAI), and Total Marrow Irradiation (TMI).

Main Methods:

• Three challenging clinical radiotherapy scenarios were selected.
• CT datasets were used to calculate dosimetry and treatment time for Regular HT (2.5 cm and 5.0 cm field widths) and DJDC HT (5.0 cm maximum field width).
• Key metrics included target coverage, conformity, integral dose, OAR exposure, and treatment duration.

Main Results:

• Both Reg 5.0 cm and DJDC 5.0 cm significantly reduced treatment times across all evaluated scenarios compared to Reg 2.5 cm.
• DJDC HT demonstrated a substantially lower integral dose due to a smaller dose penumbra, despite minor increases in dose to specific OARs (kidneys, parotid glands, thyroid).
• OAR exposure was comparable between Reg 5.0 cm and DJDC 5.0 cm in Hemithoracic Irradiation and WAI.

Conclusions:

• The next-generation DJDC HT technique shows efficiency in improving radiotherapy treatment times.
• DJDC HT maintains comparable plan quality to conventional methods.
• While not yet clinically available, DJDC HT presents a promising advancement for radiotherapy delivery.