A Review of Real-Time 3D IGRT on Standard-Equipped Cancer Radiotherapy Systems: Are We at the Tipping Point for the Era of Real-Time Radiotherapy?

Publication date: Available online 14 April 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): P.J. Keall, D.T. Nguyen, R. O'Brien, P. Zhang, L. Happersett, J. Bertholet, P.R. Poulsen
PurposeUntil now, real-time 3D image guided radiotherapy (IGRT) has been the domain of dedicated cancer radiotherapy systems. However, the tipping point to the broad adoption of real-time IGRT is the availability of this technology on standard-equipped radiotherapy systems. The purpose of this work is to review real-time 3D IGRT on standard-equipped cancer radiotherapy systems, focusing on clinically implemented solutions.MethodThree groups in three continents have clinically implemented novel real-time 3DIGRT solutions on standard-equipped linear accelerators. These technologies encompass kilovoltage, combined megavoltage-kilovoltage and combined kilovoltage-optical imaging. The cancer sites treated span pelvic and abdominal tumors where respiratory motion is present. For each method the 3D-measured motion during treatment is reported. Post-treatment, dose reconstruction was used to assess the treatment quality in the presence of motion with and without real-time 3D IGRT. The geometric accuracy was quantified through phantom experiments. A literature search was conducted to identify additional real-time 3D IGRT methods that could be clinically implemented in the near future.ResultsThe real-time 3D IGRT methods were successfully clinically implemented and have been used to treat over 200 patients. Systematic target position shifts were observed using all three methods. Dose reconstruction demonstrated that the delivered dose is closer to the planned dose with real-time 3D IGRT than without real-time 3D IGRT. In addition, compromised target dose coverage and variable normal tissue doses were found without real-time 3D IGRT. The geometric accuracy results with real-time 3D IGRT had a mean error of <0.5mm and a standard deviation of less than 1.1mm. Numerous additional articles exist that describe real-time 3D IGRT methods using standard-equipped radiotherapy systems that could also be clinically implemented.ConclusionsMultiple clinical implementations of real-time 3D IGRT on standard-equipped cancer radiotherapy systems have been demonstrated. Many more approaches that could be implemented were identified. These solutions provide a pathway for the broader adoption of methods to make radiotherapy more accurate, impacting tumor and normal tissue dose, margins and ultimately patient outcomes.



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