Impact Assessment of Systemic Geometric Distortion in 1.5T Magnetic Resonance Imaging Simulation through Three‑dimensional Geometric Distortion Phantom on Dosimetric Accuracy for Magnetic Resonance Imaging‑only Prostate Treatment Planning
Issued Date
2024-01-01
Resource Type
ISSN
09716203
eISSN
19983913
Scopus ID
2-s2.0-85204986730
Journal Title
Journal of Medical Physics
Volume
49
Issue
3
Start Page
356
End Page
362
Rights Holder(s)
SCOPUS
Bibliographic Citation
Journal of Medical Physics Vol.49 No.3 (2024) , 356-362
Suggested Citation
Chaknam K., Worapruekjaru L., Suphaphong S., Stansook N., Sodkokkruad P., Asavaphatiboon S. Impact Assessment of Systemic Geometric Distortion in 1.5T Magnetic Resonance Imaging Simulation through Three‑dimensional Geometric Distortion Phantom on Dosimetric Accuracy for Magnetic Resonance Imaging‑only Prostate Treatment Planning. Journal of Medical Physics Vol.49 No.3 (2024) , 356-362. 362. doi:10.4103/jmp.jmp_62_24 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/101496
Title
Impact Assessment of Systemic Geometric Distortion in 1.5T Magnetic Resonance Imaging Simulation through Three‑dimensional Geometric Distortion Phantom on Dosimetric Accuracy for Magnetic Resonance Imaging‑only Prostate Treatment Planning
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Abstract
Aims: Magnetic resonance imaging (MRI)-only radiotherapy has emerged as a solution to address registration errors that can lead to missed dose delivery. However, the presence of systemic geometric distortion (SGD) stemming from gradient nonlinearity (GNL) and inhomogeneity of the main magnetic field (B0) necessitates consideration. This study aimed to quantitatively assess residual SGD in 1.5T MRI simulation using a three-dimensional (3D) geometric distortion phantom and evaluate its impact on dosimetric accuracy for retrospective prostate cancer patients. Materials and Methods: Ten retrospective cases of prostate cancer patients treated with volumetric modulated arc radiotherapy (VMAT) were randomly selected. A geometric distortion phantom was scanned on a 1.5T MRI simulation using a 3D T1 volumetric interpolated breath-hold examination sequence, varying bandwidth (BW), and two-phase-encoding directions. Distortion maps were generated and applied to the original computed tomography (oriCT) plan to create a distorted computed tomography plan (dCT), and a dice similarity coefficient (DSC) was observed. Dosimetric accuracy was evaluated by recalculating radiation dose for dCT plans using identical beam parameters as oriCT. Results: The SGD increased with distance from the isocenter in all series. DSC exceeded 0.95 for all plans except the rectum. Regarding GNL’s impact on dosimetric accuracy, most mean percentage errors for clinical target volume, planning target volume, and both femurs were under 2% in all plans, except for the bladder and rectum. Conclusion: SGD pre-evaluation is crucial and should be incorporated into a quality assurance program to ensure effective MRI-simulation performance before MRI-only treatment planning for prostate cancer.