Nose

Summary

This is a target in the nose that is asymmetric with respect to the midline of the patient. The target surface abuts the patient skin over a large area, mostly on the patient’s right side, with the target left of the midline being slightly deeper and needing less buildup.

The variable-thickness OptiBol shown was modeled to give a goal buildup of 15 mm to the target from any potential beam direction in order to make it easier to achieve target sparing.

Gallery

1. Axial views with a conventional uniform bolus (5 mm) modeled in the TPS (left) and the variable-thickness OptiBol with 15 mm buildup to the target (right)
2. Depth-volume histograms showing the minimum depth of target voxels for cases of no bolus, conventional (5 mm uniform) bolus, and OptiBol with goal 15 mm buildup to the underlying target
3. Photos of the silicone OptiBol with medium-sized alignment guides, shown standalone and also on a 3D-printed holder matching the patient external contours (Note: Alignment guide options are none, small, medium, and large)
4. Photo showing a linear laser “glowing” when registered in the alignment guide groove

Details on Depth-Volume Histograms (Gallery Item 2)

Variable-Thickness OptiBol (Goal 15 mm to Target)

• 100% of the target voxels have min depth ≥ 10 mm (0% target < 10 mm)
• 97% of the target voxels have min depth ≥ 14 mm
• 95% of the target voxels have min depth ≥ 14.25 mm (where 14.25 mm is 95% of the goal buildup of 15 mm for this design)
• 90% of the target voxels have min depth ≥ 15 mm

Conventional 5 mm Uniform-Thickness Bolus

• Only 50% of the target voxels have min depth ≥ 10 mm (50% target < 10 mm)
• Only 22% of the target voxels have min depth ≥ 14 mm
• Only 20% of the target voxels have min depth ≥ 14.25 mm
• Only 17% of the target voxels have min depth ≥ 15 mm

No Bolus

• Only 26% of the target voxels have min depth ≥ 10 mm (74% target < 10 mm)
• Only 8% of the target voxels have min depth ≥ 14 mm
• Only 7% of the target voxels have min depth ≥ 14.25 mm
• Only 5% of the target voxels have min depth ≥ 15 mm