Target position uncertainty during visually guided deep-inspiration breath-hold radiotherapy in locally advanced lung cancer

Publication date: Available online 27 February 2017
Source:Radiotherapy and Oncology
Author(s): Jonas Scherman Rydhög, Steen Riisgaard de Blanck, Mirjana Josipovic, Rasmus Irming Jølck, Klaus Richter Larsen, Paul Clementsen, Thomas Lars Andersen, Per Rugaard Poulsen, Gitte Fredberg Persson, Per Munck af Rosenschold
PurposeThe purpose of this study was to estimate the uncertainty in voluntary deep-inspiration breath-hold (DIBH) radiotherapy for locally advanced non-small cell lung cancer (NSCLC) patients.MethodsPerpendicular fluoroscopic movies were acquired in free breathing (FB) and DIBH during a course of visually guided DIBH radiotherapy of nine patients with NSCLC. Patients had liquid markers injected in mediastinal lymph nodes and primary tumours. Excursion, systematic- and random errors, and inter-breath-hold position uncertainty were investigated using an image based tracking algorithm.ResultsA mean reduction of 2–6mm in marker excursion in DIBH versus FB was seen in the anterior-posterior (AP), left–right (LR) and cranio-caudal (CC) directions. Lymph node motion during DIBH originated from cardiac motion. The systematic- (standard deviation (SD) of all the mean marker positions) and random errors (root-mean-square of the intra-BH SD) during DIBH were 0.5 and 0.3mm (AP), 0.5 and 0.3mm (LR), 0.8 and 0.4mm (CC), respectively. The mean inter-breath-hold shifts were −0.3mm (AP), −0.2mm (LR), and −0.2mm (CC).ConclusionIntra- and inter-breath-hold uncertainty of tumours and lymph nodes were small in visually guided breath-hold radiotherapy of NSCLC. Target motion could be substantially reduced, but not eliminated, using visually guided DIBH.



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