Introduction: SABR may facilitate treatment in a greater proportion of locally-advanced NSCLC patients, just as it has for early-stage disease. The oesophagus is one of the key dose-limiting organs and visualization during IGRT would better ensure toxicity is avoided. As the oesophagus is poorly seen on CBCT, we assessed the extent to which this is improved using two oral contrast agents.
Materials & methods: Six patients receiving radiotherapy for Stage I-III NSCLC were assigned to receive 50 mL Gastrografin or 50 mL barium sulphate prior to simulation and pre-treatment CBCTs. Three additional patients who did not receive contrast were included as a control group. Oesophageal visibility was determined by assessing concordance between six experienced observers in contouring the organ. 36 datasets and 216 contours were analysed. A STAPLE contour was created and compared to each individual contour. Descriptive statistics were used and a Kappa statistic, Dice Coefficient and Hausdorff distance were calculated and compared using a t-test. Contrast-induced artefact was assessed by observer scoring.
Results: Both contrast agents significantly improved the consistency of oesophagus localisation on CBCT across all comparison metrics compared to CBCTs without contrast. Barium performed significantly better than Gastrografin with improved kappa statistics (p = 0.007), dice coefficients (p < 0.001) and Hausdorff distances (p = 0.002), although at a cost of increased image artefact.
Discussion: Barium produced lower delineation uncertainties but more image artefact, compared to Gastrografin and no contrast. It is feasible to use oral contrast as a tool in IGRT to help guide clinicians and therapists with online matching and monitoring of the oesophageal position.
Keywords: Cone-beam computed tomography; Oesophagus; Oral contrast; Stereotactic body radiotherapy.
Crown Copyright © 2019 Published by Elsevier B.V. on behalf of European Society for Radiotherapy & Oncology.
Conflict of interest statement
The author declare that there is no conflict of interest.
Contouring variability of human- and deformable-generated contours in radiotherapy for prostate cancer.Phys Med Biol. 2015 Jun 7;60(11):4429-47. doi: 10.1088/0031-9155/60/11/4429. Epub 2015 May 19. Phys Med Biol. 2015. PMID: 25988718
Combining prior day contours to improve automated prostate segmentation.Med Phys. 2013 Feb;40(2):021722. doi: 10.1118/1.4789484. Med Phys. 2013. PMID: 23387745
Evaluation of a commercial DIR platform for contour propagation in prostate cancer patients treated with IMRT/VMAT.J Appl Clin Med Phys. 2020 Feb;21(2):14-25. doi: 10.1002/acm2.12787. J Appl Clin Med Phys. 2020. PMID: 32058663 Free PMC article.
A feature alignment score for online cone-beam CT-based image-guided radiotherapy for prostate cancer.Med Phys. 2018 Jul;45(7):2898-2911. doi: 10.1002/mp.12980. Epub 2018 Jun 8. Med Phys. 2018. PMID: 29772077
kV cone-beam CT-based IGRT: a clinical review.Strahlenther Onkol. 2011 May;187(5):284-91. doi: 10.1007/s00066-011-2236-4. Epub 2011 Apr 26. Strahlenther Onkol. 2011. PMID: 21533757 Review.
- Robinson L.A., Ruckdeschel J.C., Wagner H., Jr., Stevens C.W. Treatment of non-small cell lung cancer-stage IIIA: ACCP evidence-based clinical practice guidelines. Chest. 2007;132(3 Suppl):243s–265s. - PubMed
- Auperin A., Le Pechoux C., Rolland E., Curran W.J., Furuse K., Fournel P. Meta-analysis of concomitant versus sequential radiochemotherapy in locally advanced non-small-cell lung cancer. J Clin Oncol. 2010;28(13):2181–2190. - PubMed
- Coate L.E., Massey C., Hope A., Sacher A., Barrett K., Pierre A. Treatment of the elderly when cure is the goal: the influence of age on treatment selection and efficacy for stage III non-small cell lung cancer. Journal of Thoracic Oncology. 2011;6(3):537–544. - PubMed
- Driessen E.J.M., Bootsma G.P., Hendriks L.E.L., van den Berkmortel F.W.P.J., Bogaarts B.A.H.A., van Loon J.G.M. Stage III non-small cell lung cancer in the elderly: patient characteristics predictive for tolerance and survival of chemoradiation in daily clinical practice. Radiother Oncol. 2016;121(1):26–31. - PubMed