Date Approved

8-7-2026

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

School of Interdisciplinary Health

First Advisor

Sarah Johnson

Academic Year

2025/2026

Abstract

Abstract

Purpose: Research easily accessible substitutes for Superflab which conform better to the patient surface and are more conformal in an attempt to increase efficacy of bolus for clinical use.

Methods: For this experiment, sand and rice were measured based on Hounsfield units (HU) and relative electron density (RED) and placed into bags to be formed to a patient surface, securing their shape through the use of a vacuum sealer. After repeated CT scans with the chosen materials, plans were calculated on each scan followed by measurement of HU, air gap volume, bolus volume, and dosimetric parameters including monitor units and PTV coverage. Sand was removed from the process after fabrication due to its failure to hold a consistent shape.

Results: Upon measurement and data analysis, the mean, minimum, and Hounsfield Unit (HU) measurements between rice and Superflab presented a difference which was statistically significant. Although the measured air gaps in the rice bolus were consistently lower than that of the Superflab, these results were not statistically significant. The Superflab bolus exhibited superior mean, maximum, and minimum values in terms of PTV coverage, all of which were statistically significant. The difference in monitor units between the rice bolus and Superflab bolus plans was statistically significant.

Conclusion: This study suggests that rice is not a superior substitute to Superflab as bolus material. It was shown that although more conformal and reproducible, this is not statistically significant which is seen in the plan analysis where PTV coverage is statistically better in the plans calculated with Superflab bolus.

Key words: Superflab, bolus, rice, conformal, air gaps

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