Image distortion in MRI-based polymer gel dosimetry of gamma knife stereotactic radiosurgery systems
| Autor: | Gerard M. Perera, Yoichi Watanabe, Robertus B. Mooij |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Physics
medicine.diagnostic_test Phantoms Imaging Polymers medicine.medical_treatment Radiotherapy Planning Computer-Assisted Biophysics Magnetic resonance imaging General Medicine equipment and supplies Radiosurgery Magnetic Resonance Imaging Imaging phantom Biophysical Phenomena Nuclear magnetic resonance Distortion Medical imaging medicine Dosimetry Humans Computed radiography Fiducial marker Radiometry Gels |
| Zdroj: | Medical physics. 29(5) |
| ISSN: | 0094-2405 |
| Popis: | We have studied effects of MR (magnetic resonance) image distortion on polymer gel dosimetry of Gamma Knife stereotactic radiosurgery systems. MR images of BANG polymer gel phantoms were acquired by using a Hahn spin-echo sequence and a fast 3D imaging GRASS sequence. Image artifacts were studied by varying the directions of frequency encoding and the receiver bandwidth. The phantoms were also CT (computed tomography) scanned. The studies showed that the measured dose distributions are shifted by 1.8+/-0.5 mm (2 pixels) in the frequency encoding direction. The magnitude of the shift is inversely proportional to the receiver bandwidth in agreement with theory. Comparison of MRI with CT showed the same image shift. We concluded that the discrepancy is caused by MR image distortion due to a difference in susceptibility effects between the phantom and the fiducial markers of the Leksell localization box. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text