Single fraction partial breast irradiation in prone position

Area of Science:

• Radiation Oncology
• Medical Physics
• Surgical Oncology

Background:

• Partial breast irradiation (PBI) is an alternative to whole breast irradiation.
• Accelerated PBI techniques aim to reduce treatment time.
• Prone positioning may offer dosimetric advantages for breast irradiation.

Purpose of the Study:

• To introduce and evaluate a novel single-session prone partial breast irradiation technique.
• To assess the feasibility and early toxicity of this approach.
• To determine the dosimetric outcomes of the proposed technique.

Main Methods:

• A dedicated positioning device and immobilization system were used for prone breast positioning.
• Clinical target volume (CTV) was defined based on surgical clips and mammography.
• Planning target volume (PTV) was created with a 3 mm margin.
• A dose of 21 Gy to PTV was prescribed using 3D-CRT with 5 fields.
• Patients were treated in a single session.

Main Results:

• High PTV coverage achieved: 99.9% within 90% and 98.6% within 95% of prescribed dose.
• Minimal overdose to PTV (3.4% > 105% of prescribed dose).
• Limited skin dose (15.2 Gy to 3% of skin volume).
• Low dose to surrounding organs at risk (lungs, heart, contralateral breast).
• No significant early toxicity observed at 9-month median follow-up.

Conclusions:

• Single-session prone partial breast irradiation using 3D-CRT is technically feasible.
• The technique demonstrates favorable dose distribution and early toxicity profile.
• This approach represents a promising alternative for accelerated partial breast irradiation.