2D patient setup veri fication in MRI-only radiotherapy versus current CT-based veri fication |
Manija Ghafory
|
| Abstract | Radiation therapy (RT) is one of the most common treatment method for cancer patients. The purpose of RT is to cure the patient through ionizing radiation. This requires a treatment planning process with high accuracy. The current treatment planning is based on a computed tomography (CT) scan which contains information about the electron densities, which are required for dose calculation. The CT scan is also important for 2D patient setup verification. RT based on magnetic resonance imaging (MRI) has proved advantages compared to the CT due to e.g. better delineation of tumour volume and organ at risks. The aim of this study is to investigate the possibility of using MRI for 2D patient setup veri fication.
Data from four palliative patients receiving cranial RT was used in this study. The patients were scanned with 1 Tesla open MRI-system and MRI ultrashort echo-time (UTE) sequence scans were required. The Markov random fi eld (MRF) segmentation method was used to classify each MRI UTE sequence data into air, soft tissue and bone and created a substituted CT (sCT) scans. sCT bone digital reconstructed radiographs (DRRs) were generated from the sCT scans and CT bone DRRs were generated from the planning CT scans. Manual match of OBIs on both CT DRRs and sCT DRRs were performed in Offine Review Eclipse V.10 (Varian Medical System). A 2D lateral and frontal match was performed by ve radiation therapists (RTTs). A statistical evaluation was made of whether there is a signi ficant difference in 2D patient setup veri fication when performing matching on sCT generated DRRs as compared to CT generated DRRs.
The MRF segmentation facilitated creating sCT scan and generated bone DRRs.
A signifi cant difference between the sCT and CT generated DRRs was seen in longitudinal (lateral) direction, vertical direction and pitch (rotation) when performing 2D lateral match. For the frontal match a signifi cant difference was observed in rnt (rotation) whereas longitudinal (front) and lateral directions were non-significant.
This study showed that treatment planning solely based on MRI is a feasible alternative to current CT based on treatment planning due to 2D setup verification. |
| Type | Master's thesis [Academic thesis] |
| Year | 2013 |
| Publisher | Technical University of Denmark, DTU Compute, E-mail: compute@compute.dtu.dk |
| Address | Matematiktorvet, Building 303-B, DK-2800 Kgs. Lyngby, Denmark |
| Series | M.Sc.-2013-23 |
| Note | DTU supervisor: Rasmus Larsen, rlar@dtu.dk, DTU Compute |
| Electronic version(s) | [pdf] |
| Publication link | http://www.compute.dtu.dk/English.aspx |
| BibTeX data | [bibtex] |
| IMM Group(s) | Image Analysis & Computer Graphics |