The first clinical implementation of electromagnetic transponder‐guided MLC tracking. Issue 2 (23rd January 2014)

• Record Type: Journal Article
• Authors: Keall, Paul J.; Colvill, Emma; O'Brien, Ricky; Ng, Jin Aun; Poulsen, Per Rugaard; Eade, Thomas; Kneebone, Andrew; Booth, Jeremy T.
• Is Part Of: Medical physics. Volume 41:Issue 2(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-01-23
• Subjects: Dose‐volume analysis -- Quality assurance in radiotherapy -- Tissue response -- Conformal radiation treatment -- Dosimetry/exposure assessment -- Reconstruction; beam handling techniques -- cancer -- dosimetry -- image reconstruction -- medical image processing -- object tracking -- radiation therapy -- transponders; real‐time adaptation -- beam‐tumor targeting -- MLC tracking -- clinical translation; Radiation therapy -- Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Responders; Transponders -- Scintigraphy; Multileaf collimators -- Dosimetry -- Cancer -- Motion compensation -- Quality assurance -- Linear accelerators -- Computer software -- Therapeutics -- Computed tomography -- Electromagnetic therapy; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4862509
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : We report on the clinical process, quality assurance, and geometric and dosimetric results of the first clinical implementation of electromagnetic transponder‐guided MLC tracking which occurred on 28 November 2013 at the Northern Sydney Cancer Centre. Methods: : An electromagnetic transponder‐based positioning system (Calypso) was modified to send the target position output to in‐house‐developed MLC tracking code, which adjusts the leaf positions to optimally align the treatment beam with the real‐time target position. Clinical process and quality assurance procedures were developed and performed. The first clinical implementation of electromagnetic transponder‐guided MLC tracking was for a prostate cancer patient being treated with dual‐arc VMAT (RapidArc). For the first fraction of the first patient treatment of electromagnetic transponder‐guided MLC tracking we recorded the in‐room time and transponder positions, and performed dose reconstruction to estimate the delivered dose and also the dose received had MLC tracking not been used. Results: : The total in‐room time was 21 min with 2 min of beam delivery. No additional time was needed for MLC tracking and there were no beam holds. The average prostate position from the initial setup was 1.2 mm, mostly an anterior shift. Dose reconstruction analysis of the delivered dose with MLC tracking showed similar isodose and target dose volume histograms to the planned treatment and a 4.6% increase in the fractional rectal V60 . Dose reconstruction without motion compensation showed a 30% increase in the fractional rectal V60 from that planned, even for the small motion. Conclusions: : The real‐time beam‐target correction method, electromagnetic transponder‐guided MLC tracking, has been translated to the clinic. This achievement represents a milestone in improving geometric and dosimetric accuracy, and by inference treatment outcomes, in cancer radiotherapy.