A simpler method for total scalp irradiation: the multijaw-size concave arc technique

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Lateral electron-photon technique (LEPT) and intensity-modulated radiation therapy (IMRT) are standard for total scalp irradiation but are time-consuming.
• Efficient and effective scalp irradiation techniques are crucial for treating conditions like angiosarcoma.

Purpose of the Study:

• To introduce and evaluate the multijaw-size concave arc technique (MCAT) for total scalp irradiation.
• To compare MCAT with LEPT and IMRT regarding treatment planning, dose distribution, delivery efficiency, and safety.

Main Methods:

• CT datasets from eight scalp angiosarcoma patients were re-planned using MCAT, LEPT, and IMRT.
• MCAT involved a dynamic conformal arc with a multileaf collimator for brain shielding and additional arcs to mitigate cranial hotspots.
• Treatment plans were assessed for planning target volume (PTV) dose homogeneity, underdosage, overdosage, brain dose, delivery time, and monitor units (MUs).

Main Results:

• All three techniques successfully delivered the prescribed 40 Gy dose to 95% of the PTV.
• MCAT demonstrated superior PTV dose homogeneity and reduced under/overdosage compared to LEPT.
• MCAT showed reduced delivery time (by ~50%) and MUs (by at least 100) compared to LEPT and IMRT.
• While IMRT offered slightly better dose homogeneity, MCAT was comparable and significantly more efficient.

Conclusions:

• The multijaw-size concave arc technique (MCAT) is a viable and efficient method for total scalp irradiation.
• MCAT significantly reduces treatment time and MUs, offering a practical alternative to LEPT and IMRT.
• MCAT provides effective dose delivery to the scalp while minimizing radiation exposure to the brain.