Date Approved

7-3-2026

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

School of Interdisciplinary Health

First Advisor

Bethany Marshall M.S., CMD, RT(T)

Second Advisor

Kristen Vu

Academic Year

2025/2026

Abstract

Purpose: The purpose of this research was to quantify how varying hair conditions—dry hair versus wet hair, complete hair loss, and the use of hair extensions—influence surface dose during WBRT. The study evaluated mask fit differences between the varying hair parameters and the potential implications for immobilization accuracy.

Methods: Four CT scans were acquired with a water phantom and varying hair parameters. A whole brain radiation therapy (WBRT) plan was created on a dry wig human hair scan using 6MV photos. Thermoluminescent dosimeters (TLDs) were used to measure surface dose for each hair condition. Gap between the water phantom and the thermoplastic mask was measured at user origin for immobilization accuracy on each CT scan. The plan was re-calculated with fixed MU on wet hair, no hair, and added hair CT scans to quantify the difference to the whole brain.

Results: TLD data for the four hair-type surface dose measurements were compared using dose ratios. No statistically significant differences were observed between the varying hair plans (p= 0.455). The Kruskal–Wallis test was also used to evaluate differences in gap measurements and mask fit among the four hair types. No statistically significant differences were observed between the varying hair plans (p=0.058). Descriptive statistics were used to evaluate percent differences in MU. Maximum and mean doses were similar across all four plans with a 20.83 minimum absolute percent change observed on the X2 wig plan.

Conclusions: No statistically significant differences were observed in surface dose, gap measurements, mask fit, or MU. This study reinforces current clinical practices that varying hair conditions do not affect radiation treatment planning and delivery.

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