Planning and delivery of four-dimensional radiation therapy with multileaf collimators

2008 2008

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Abstract (summary)

This study is an investigation of the application of multileaf collimators (MLCs) to the treatment of moving anatomy with external beam radiation therapy. First, a method for delivering intensity modulated radiation therapy (IMRT) to moving tumors is presented. This method uses an MLC control algorithm that calculates appropriate MLC leaf speeds in response to feedback from real-time imaging. The algorithm does not require a priori knowledge of a tumor’s motion, and is based on the concept of self-correcting DMLC leaf trajectories . This gives the algorithm the distinct advantage of allowing for correction of DMLC delivery errors without interrupting delivery. The algorithm is first tested for the case of one-dimensional (1D) rigid tumor motion in the beam’s eye view (BEV). For this type of motion, it is shown that the real-time tracking algorithm results in more accurate deliveries, with respect to delivered intensity, than those which ignore motion altogether. This is followed by an appropriate extension of the algorithm to two-dimensional (2D) rigid motion in the BEV. For this type of motion, it is shown that the 2D real-time tracking algorithm results in improved accuracy (in the delivered intensity) in comparison to deliveries which ignore tumor motion or only account for tumor motion which is aligned with MLC leaf travel. Finally, a method is presented for designing DMLC leaf trajectories which deliver a specified intensity over a moving tumor without overexposing critical structures which exhibit motion patterns that differ from that of the tumor. In addition to avoiding overexposure of critical organs, the method can, in the case shown, produce deliveries that are superior to anything achievable using stationary anatomy. In this regard, the method represents a systematic way to include anatomical motion as a degree of freedom in the optimization of IMRT while producing treatment plans that are deliverable with currently available technology. These results, combined with those related to the real-time MLC tracking algorithm, show that an MLC is a promising tool to investigate for the delivery of four-dimensional radiation therapy.

Indexing (details)

Biomedical engineering;
Nuclear physics;
0541: Biomedical engineering
0756: Nuclear physics
0992: Medicine
Identifier / keyword
Health and environmental sciences; Applied sciences; Pure sciences; Four-dimensional therapy; Intensity-modulated radiation therapy; Multileaf collimators; Organ motion; Radiation therapy; Respiratory motion
Planning and delivery of four-dimensional radiation therapy with multileaf collimators
McMahon, Ryan L.
Number of pages
Publication year
Degree date
School code
DAI-B 70/01, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Papiez, Lech; Sandison, George
Committee member
Langer, Mark; Stantz, Keith; Stewart, Robert D.
Purdue University
Health Sciences
University location
United States -- Indiana
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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