Date Approved


Graduate Degree Type


Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Lee Culp

Academic Year



One of the most important organs in the body is the brain; It controls numerous functions vital for everyday life. Due to the compactness of the brain, introducing even the smallest abnormal growth can cause cranial pressure resulting in symptoms such as loss of vision, headaches, reduction of memory and seizures1. Brain lesions can present as cancerous, noncancerous, or metastatic. Treatment options for cranial lesions are dependent on the pathology, histology, and stage of the tumor: with chemotherapy, surgery, and radiation therapy being the most common. A few radiation therapy techniques include 3D conformal radiation therapy (3DCRT), gamma knife, volumetric modulated arc therapy (VMAT), and stereotactic radiosurgery (SRS).

Stereotactic radiosurgery is a noninvasive treatment option for lesions that may be unresectable or near critical organs. A newly developed planning technique for SRS treatments was developed by Varian Medical Systems named HyperArcTM generating patient specific beam parameters to spare as many critical organs as possible. A prior research study investigated RapidArcTM plans to original HyperArcTM plans to determine if a non-HyperArcTM plan could give similar or better Dosimetric outcomes. Further investigation to determine if a dosimetrist could create the same or better results with RapidArcTM planning through the addition of Dosimetric rings is the purpose of this research.

The paired sample T Test was used to gather statistical data to determine critical organ mean doses, maximum doses, and target conformity. All treatment plans were prescribed to the Gross Tumor Volume (GTV) with 12 Gy in 1 fraction and normalized so that 100% of prescription dose covered 99% of the target. When evaluating the benefit of using the HyperArcTM technique compared to the RapidArcTM it was found that the inclusion of rings on the RapidArcTM plans using Auto 500 (NTO) mimicked plans using HyperArcTM with minor variations. The drawn conclusion was that both HyperArcTM and RapidArcTM with rings and Auto 500 (NTO) are viable techniques in the treatment planning for brain lesions.