Analysis of 3D and 4D proton treatment planning for hepatic tumors
Name
824560127-MIT.pdf
Description
Full printable version
Size
6.08 MB
Format
Adobe PDF
Checksum (MD5)
35ddf7532c8a5c9f7c8a4058f9ce2fcd
Author(s)
Wiśniowska, Agata Elżbieta
Advisor(s)
Richard Lanza and George T.Y. Chen.
Alternative Title
Analysis of three-dimensional and four-dimensional proton treatment planning for hepatic tumors
Date Issued
2011
Publisher
Massachusetts Institute of Technology
Abstract
The purpose of this study is to assess the difference between 4D liver dose calculations versus standard 3D treatment planning and to investigate the dosimetric gain of gating on radiation dose to normal tissue. 4DCT scans are collected for 25 patients with hepatic tumors treated by proton radiotherapy. The 4D treatment planning process explicitly takes into account respiratory motion of abdominal organs. A 4DCT scan consists of 10 3D anatomical states, each at an instant of time in the respiratory cycle. 4D treatment planning includes 1) propagating the target contours, drawn by a physician on one phase, to all breathing phases using deformable registration, 2) calculating the compensating bolus for proton therapy, and then 3) calculating 4D dose distributions. Dose volume histograms are used to compute the effective uniform dose (EUD) delivered to normal liver. We found that 4DCT planning always results in a larger EUD to normal liver when compared with dose from a 3DCT plan. The mean EUD difference between 4D and 3D planning is 3.8Gy ([sigma]= 1.9Gy, p<0.000 1). Gated 4D treatment planning results in a lower EUD to normal liver compared to ungated planning, with a mean difference of 2.9 Gy ([sigma]=1.9Gy, p<0.0001). The EUD difference is only weakly correlated with the magnitude of the superior-inferior (S-I) tumor motion ([tau]=0.59 for 4D/3D, [tau]=0.48 for ungated/gated). The [Delta]EUD correlation with clinical target volume (CTV) (as fraction of liver volume) is much weaker ([tau]-0.31 for 4D/3D, [tau]=0.26 for ungated/gated). There was no evidence that the tumor position within the liver influenced the [Delta]EUD. This study suggests that physicians should consider 4D treatment planning if the risk of normal tissue complications is high. Normal tissues may also be significantly spared by gated treatment as a motion management strategy.
Description
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2011.
"June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 33-34).
Subjects
Nuclear Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Terms of Use
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
Persistent DSpace Link
