A dosimetric comparison of real-time adaptive and non-adaptive radiotherapy: A multi-institutional study encompassing robotic, gimbaled, multileaf collimator and couch tracking

Abstract

PurposeA study of real-time adaptive radiotherapy systems was performed to test the hypothesis that, across delivery systems and institutions, the dosimetric accuracy is improved with adaptive treatments over non-adaptive radiotherapy in the presence of patient-measured tumor motion.Methods and materialsTen institutions with robotic(2), gimbaled(2), MLC(4) or couch tracking(2) used common materials including CT and structure sets, motion traces and planning protocols to create a lung and a prostate plan. For each motion trace, the plan was delivered twice to a moving dosimeter; with and without real-time adaptation. Each measurement was compared to a static measurement and the percentage of failed points for γ-tests recorded.ResultsFor all lung traces all measurement sets show improved dose accuracy with a mean 2%/2 mm γ-fail rate of 1.6% with adaptation and 15.2% without adaptation (p < 0.001). For all prostate the mean 2%/2 mm γ-fail rate was 1.4% with adaptation and 17.3% without adaptation (p < 0.001). The difference between the four systems was small with an average 2%/2 mm γ-fail rate of <3% for all systems with adaptation for lung and prostate.ConclusionsThe investigated systems all accounted for realistic tumor motion accurately and performed to a similar high standard, with real-time adaptation significantly outperforming non-adaptive delivery methods.

Respiratory motion-management in stereotactic body radiation therapy for lung cancer – A dosimetric comparison in an anthropomorphic lung phantom (LuCa)

“…Other tracking systems are assumed to give similar benefits for tracking over other motion-management techniques. A multi-institutional study was performed by Colvill et al [23] to compare real-time adaptive therapy with robotic, gimbaled, MLC and couch tracking. The four modalities were found to perform similarly on the 2%/2 mm and 3%/3 mm failure criteria.…”

Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

“…To estimate individual systematic correlation, prediction, and rotation errors, we used the average over Preprint to be submitted to International Journal of Radiation Oncology * Biology * Physics [7] Pseudo 4D Error Dose Calculation…”

“…This method also has been described as highly accurate in phantoms [7,13,14], in simulations [15,16], and in patients [17][18][19][20][21], allowing the application of high radiation doses inside the gross and clinical tumor volume (GTV/CTV) while applying minimal safety margins to maximize sparing of the surrounding normal tissue. The resulting high local tumor control rates for liver lesions have been published repeatedly [22][23][24].…”

Validation of dynamic treatment-couch tracking for prostate SBRT

“…A multi‐institutional study compared real‐time adaptive therapy with robotic, gimbaled, MLC, and couch tracking. Over all tracking modalities, the mean gamma failure rate of prostate treatments decreased from 17.3% with no adaptation to 1.4% with motion adaptation.…”