MRI-only planning is an emerging approach in radiotherapy that eliminates the need for CT scans in the planning process. Traditionally, CT imaging has been the gold standard for treatment planning due to its ability to provide electron density information required for dose calculations. However, the use of MRI offers several distinct advantages, including superior soft-tissue contrast, reduced radiation exposure to patients, and the potential for a streamlined workflow.
Advantages of MRI-Only Planning
One of the primary benefits of MRI-only planning is its ability to provide exceptional soft-tissue visualisation. This is particularly valuable in treating cancers in areas like the brain, prostate, and pelvis, where precise delineation of tumour boundaries and surrounding organs at risk is crucial. The high resolution of MRI enables clinicians to achieve better target localisation and potentially improve treatment outcomes.
MRI-only planning also eliminates the need for patients to undergo both CT and MRI scans. This reduces overall scanning time, minimises patient discomfort, and decreases costs associated with dual imaging modalities. Additionally, it avoids the cumulative radiation dose from CT scans, which is particularly advantageous for patients requiring multiple imaging sessions over time.
Challenges and Solutions
Despite its advantages, MRI-only planning is not without challenges. A significant hurdle is the lack of electron density information in MRI scans, which is essential for accurate dose calculation. To address this, synthetic CT (sCT) images are generated from MRI data using advanced algorithms and machine learning techniques. These sCT images provide the required electron density information, enabling accurate dose planning without the need for CT imaging.
Another challenge is geometric distortions inherent in MRI due to magnetic field inhomogeneities and gradient non-linearities. Modern MRI systems and correction algorithms have largely mitigated these issues, ensuring accurate image geometry for treatment planning.
Implementation in Clinical Practice
The successful implementation of MRI-only planning requires careful consideration of workflow integration and staff training. Radiotherapy departments need to ensure that their MRI systems are optimised for treatment planning, including the use of dedicated coils and sequences. Additionally, staff must be trained in MRI interpretation and the generation of sCT images to maintain accuracy and efficiency.
Many centres have started adopting MRI-only planning, particularly for prostate cancer treatment. Studies have shown that the approach is clinically feasible and can achieve dosimetric accuracy comparable to conventional CT-based planning. As technology continues to advance, MRI-only planning is expected to become increasingly prevalent across a broader range of cancer types.
Conclusion
MRI-only planning represents a significant advancement in radiotherapy, combining the benefits of improved soft-tissue contrast, reduced radiation exposure, and streamlined workflows. While challenges remain, ongoing technological developments and clinical experience are paving the way for its wider adoption in modern radiotherapy practices.
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| 9 minutes of reading | 2025-05-07 Learn how automated medical workflows transform healthcare by streamlining tasks and improving the efficiency of medical staff. Image for illustration only. People depicted are models.
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