Date Approved

8-13-2021

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

Health Professions

First Advisor

Lauren Rydquist

Academic Year

2020/2021

Abstract

Abstract

In this study, a four-arc partial field hippocampal sparing volumetric arc treatment technique plan was compared to a two-arc plan with open fields to determine if there was a superior planning technique between the two hippocampal sparing techniques. The planning objectives that the two types of plans adhered to were outlined in the Radiation Therapy Oncology Group (RTOG) 0933 protocol (2011). This retrospective based study used the data from 10 eligible patients who were 18 years or older and had previously received hippocampal avoidance whole brain radiation therapy between the years 2019 and 2021. From this data, the researcher created two plans for each patient, each plan utilizing one of the two techniques tested. Statistical analysis showed that the 4 Partial Beam Arcs treatment technique showed only slight advantages over the 2 Open Arcs plans. The variable 2% PTV WB_Max (cGy) was deemed to have a significant difference between the two plans (p = 0.002), the Hot Spot % measure results deemed that there was a significant difference between the two tested treatment techniques (p = 0.002), and for the Total MU measure the results deemed that there was also a significant difference between the two tested treatment techniques (p = 0.002). This study provides a great platform for other studies to continue research conducted comparing other hippocampal sparing VMAT techniques. Continued research on this subject will narrow the results to the best way to plan for this sort of treatment. Finding the best treatment planning technique that most consistently meets the treatment planning criteria is extremely beneficial for clinics to have further consistency in planning overall between dosimetrists for hippocampal avoidance whole brain treatments.

Keywords: Hippocampal sparing whole brain treatment, RTOG 0933 Protocol, VMAT techniques, hippocampal avoidance, retrospective comparison study

Comments

Spectrum Health, Lemmen-Holton Cancer Center

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