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  4. Patient Dose Accuracy Improvements for Patients Treated in the TROG 15.01 Stereotactic Prostate Ablative Radiotherapy with Kilovoltage Intrafraction Monitoring (SPARK) Trial

Patient Dose Accuracy Improvements for Patients Treated in the TROG 15.01 Stereotactic Prostate Ablative Radiotherapy with Kilovoltage Intrafraction Monitoring (SPARK) Trial

EA Hewson1*, DT Nguyen1,2, R O'Brien1, P Poulsen3, J Booth4,5, P Greer6, T Eade4, A Kneebone4, G Hruby4, T Moodie7, A Hayden7, S Turner7, N Hardcastle8, S Siva8, K Tai8, M Sidhom9, S Arumugam9, J Martin6, P Keall1, (1) ACRF Image X Institute, University of Sydney Medical School, NSW, AU, (2) School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW, AU, (3) Department of Oncology, Aarhus University Hospital, Aarhus, DK, (4) Northern Sydney Cancer Centre, Royal North Shore Hospital, NSW, AU, (5) School of Physics, University of Sydney, NSW, AU, (6) Calvary Mater Newcastle, Waratah, NSW, AU, (7) Crown Princess Mary Cancer Centre, Westmead, NSW, AU, (8) Peter MacCallum Cancer Centre, VIC, AU, (9) Liverpool Hospital, Liverpool and Macarthur Cancer Therapy Centres, NSW, AU

Presentations

(Wednesday, 7/15/2020) 4:30 PM - 5:30 PM [Eastern Time (GMT-4)]

Room: Track 2

Purpose:
Increasing interest in stereotactic ablative radiotherapy (SABR) has boosted the need for real-time image-guided radiotherapy (IGRT). Kilovoltage Intrafraction Monitoring (KIM) is an image-guidance technology that utilizes the on-board kV imager on a linac to achieve real-time motion monitoring. This study reported the total dose improvement received by patients treated in the TROG15.01 Stereotactic Prostate Ablative Radiotherapy with KIM (SPARK) trial.

Methods:
Forty-four prostate cancer patients were treated across four institutions using KIM-guided SABR with 36.25Gy prescribed to the PTV. Prostate motion was monitored using KIM and corrected in real-time using gating and couch-shifts (34 patients) or MLC tracking (10 patients). The dose delivered to the prostate and organs at risk was retrospectively evaluated using a motion-encoded dose-reconstruction method and compared to an estimation of what would have been delivered without real-time IGRT.

Results:
39/44 (89%) patients had at least one fraction where motion was corrected. The patient dose over five fractions showed that all patients treated with real-time IGRT received a dose within 5% of the planned PTV D95%. Without real-time IGRT, six patients (14%) would not have received a dose within 5% of the planned PTV D95%. When real-time IGRT was used, the range of differences between the plan and delivered doses for the CTV D98%, PTV D95%, rectum V30Gy, and bladder V30Gy were [-0.9%, 1.1%], [-2.3%, -0.8%], [-1.8%, 1.4%] and [-1.4%, 1.7%] respectively. If patients were treated without real-time IGRT the range of differences would have been [-5.6%, 1.1%], [-17.0%, 0.8%], [-6.2%, 1.2%] and [-2.9%, 8.5%] respectively.

Conclusion:
For the first time, the total dose delivered over a SABR course for prostate cancer patients treated using KIM-guidance was quantified. Without real-time IGRT, the dose to the targets of 14% of the trial cohort would be compromised, further emphasizing the importance of real-time IGRT for high dose treatments.

Funding Support, Disclosures, and Conflict of Interest: The authors acknowledge funding from Cancer Australia. PJK is an inventor of licensed and unlicensed patents related to the KIM technology.

Keywords

Image-guided Therapy, Prostate Therapy

Taxonomy

TH- External Beam- Photons: Motion management - intrafraction

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