Date of Graduation
8-2014
Document Type
Thesis (MS)
Program Affiliation
Medical Physics
Degree Name
Masters of Science (MS)
Advisor/Committee Chair
Stephen Kry, PhD.
Committee Member
David Followill, PhD
Committee Member
Anita Mahajan, MD
Committee Member
Narayan Sahoo, PhD.
Committee Member
Francesco Stingo, PhD.
Committee Member
Paige Summers, MS
Abstract
Proton therapy is gaining acceptance as a cancer treatment modality, as it allows for dose deposition to the target volume while sparing the surrounding healthy tissue. This technique is advantageous for craniospinal pediatric patients, as it reduces the radiation side effects that can occur. The purpose of this study is to design an anthropomorphic pediatric spine phantom for use in the evaluation of proton therapy facilities for clinical trial participation by the Imaging and Radiation Oncology Core (IROC) Houston QA Center. It was hypothesized that the designed phantom would evaluate patient simulation, treatment planning and delivery, assuring agreement between the measured and calculated doses within 5%/3mm, with 85% of pixels passing criteria for gamma analysis and also a TLD point dose agreement within 5%. Tissue equivalency was determined by measuring the relative stopping power and Hounsfield unit of potential phantom materials. The materials selected as bone, tissue, and cartilage substitutes were Techron HPV Bearing Grade (RSP 1.3, HU 595.6), solid water (RSP 1.004, HU 16), and blue water (RSP 1.07, HU 86), respectively. The design also incorporates two thermoluminescent dosimeter (TLD)-100 capsules and radiochromic film embedded for dose evaluation. CT images of the phantom were acquired and used to create passive scattering and spot scanning treatment plans. Each plan was delivered three times at a dose of 6 Gy. The following attributes were evaluated: absolute dose agreement, distal range, field width, junction match and right/left dose profile alignment. The hypothesis was accepted for the passive scattering plans, making this phantom and delivery technique suitable for use in IROC Houston proton approval process.
Keywords
IROC Proton Spine Phantom