MRIdian for kidney cancers

MRI-guided radiotherapy improves on conventional image-guided radiotherapy (IGRT) by providing enhanced soft tissue definition without additional radiation exposure through high-quality MR images.

By capturing MR images of the target many times per second, the MRIdian provides real-time, moving images that capture the anatomical position changes that occur naturally within the body. Uniquely, the MRIdian allows tracking of the target position in real time, coupled with a gating facility that prevents beam delivery when the target is outside the treatment boundaries. This level of accuracy means that uncertainty is reduced, eliminating the need for large margins around the target.

The MRIdian has opened up new avenues of treatment, particularly tumours that move and are within close proximity of organs at risk (OAR) such as tumours of the kidney, where high doses are achievable while keeping the doses to OARs within tolerance.

The MRIdian allows clinicians to provide true online adaptive radiotherapy. The treatment planning system is clear and intuitive, making daily re-contouring of tumour and normal tissues straightforward. The updated plans are rapidly re-optimised providing a personalised radiation treatment for each patient on every fraction.

• The MRIdian uses a patented split-magnet MR design so that the radiation beam is not distorted by the magnetic field and is at the optimum distance for exceptionally sharp, high dose-rate SABR 
• The MR set-up captures multiple high-definition, high-quality images many times a second, detecting even the slightest movement of the tumour and surrounding organs 
• The MRIdian allows the clinicians to perform real-time, on-table plan adjustments to reflect both inter– and intra-fraction anatomical changes or movements 
• When the gating target moves outside the pre-specified gating boundary, the radiation beam automatically stops until the target returns back inside the gating boundary 
• The gating target and gating boundary are visualised on the display and some patients benefit from being able to view this while inside the MRIdian, thus enabling them to take an active role in gated delivery by adjusting their breathing 
• Coupled with the unique target tracking and gating system is a precise stereotactic radiation beam, giving the clinician greater control and confidence in delivering maximal dose to the tumour target while preserving critical structures

References

1. Siva S, Ellis RJ, Ponsky L, Teh BS, Mahadevan A, Muacevic A, Staehler M, Onishi  H, Wersall P, Nomiya T, Lo SS. Consensus statement from the International Radiosurgery Oncology Consortium for Kidney for primary renal cell carcinoma. Future Oncol. 2016 Mar;12(5):637-645 
2. Siva S, Correa R, Warner A, Staehler M, Ellis R, Ponsky L et al. Stereotactic Ablative Radiotherapy for ≥T1b Primary Renal Cell Carcinoma: A Report From the International Radiosurgery Oncology Consortium for Kidney (IROCK). Int. J. Radiat. Oncol. Biol. Phys. 2020;108(4):941-949. 

Further reading

1. Thompson R, Ordonez M, Iasonos A, Secin F, Guillonneau B, Russo P et al. Renal Cell Carcinoma in Young and Old Patients—Is There a Difference? J. Urol. 2008;180(4):1262-1266. 
2. Kothari G, Louie A, Pryor D, Vela I, Lo S, Teh B et al. Stereotactic body radiotherapy for primary renal cell carcinoma and adrenal metastases. Chin. Clin. Oncol. 2017;6(S2):S17-S17.  
3. Buy X, Lang H, Garnon J, Sauleau E, Roy C, Gangi A. Percutaneous Renal Cryoablation: Prospective Experience Treating 120 Consecutive Tumors. AJR Am. J. Roentgenol 2013;201(6):1353-1361.  
4. Lagerveld B, Brenninkmeijer M, van der Zee J, van Haarst E. Can RENAL and PADUA Nephrometry Indices Predict Complications of Laparoscopic Cryoablation for Clinical Stage T1 Renal Tumors?. J. Endourol. 2014;28(4):464-471. 
5. Kim E, Tanagho Y, Bhayani S, Saad N, Benway B, Figenshau R. Percutaneous cryoablation of renal masses: Washington University experience of treating 129 tumours. BJU Int. 2012;111(6):872-879. 
6. Correa R, Louie A, Zaorsky N, Lehrer E, Ellis R, Ponsky L et al. The Emerging Role of Stereotactic Ablative Radiotherapy for Primary Renal Cell Carcinoma: A Systematic Review and Meta-Analysis. Eur. Urol. Focus. 2019;5(6):958-969. 
7. Rühle A, Andratschke N, Siva S, Guckenberger M. Is there a role for stereotactic radiotherapy in the treatment of renal cell carcinoma?. Clinical and Translational Radiation Oncology. 2019;18:104-112.