Sir Peter MacCallum Department of Oncology - Research Publications
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ItemCone-beam computed tomography for lung cancer - validation with CT and monitoring tumour response during chemo-radiation therapy(WILEY, 2017-04)INTRODUCTION: Cone-beam computed tomography (CBCT) is a valuable image-guidance tool in radiation therapy (RT). This study was initiated to assess the accuracy of CBCT for quantifying non-small cell lung cancer (NSCLC) tumour volumes compared to the anatomical 'gold standard', CT. Tumour regression or progression on CBCT was also analysed. METHODS: Patients with Stage I-III NSCLC, prescribed 60 Gy in 30 fractions RT with concurrent platinum-based chemotherapy, routine CBCT and enrolled in a prospective study of serial PET/CT (baseline, weeks two and four) were eligible. Time-matched CBCT and CT gross tumour volumes (GTVs) were manually delineated by a single observer on MIM software, and were analysed descriptively and using Pearson's correlation coefficient (r) and linear regression (R2 ). RESULTS: Of 94 CT/CBCT pairs, 30 patients were eligible for inclusion. The mean (± SD) CT GTV vs CBCT GTV on the four time-matched pairs were 95 (±182) vs 98.8 (±160.3), 73.6 (±132.4) vs 70.7 (±96.6), 54.7 (±92.9) vs 61.0 (±98.8) and 61.3 (±53.3) vs 62.1 (±47.9) respectively. Pearson's correlation coefficient (r) was 0.98 (95% CI 0.97-0.99, ρ < 0.001). The mean (±SD) CT/CBCT Dice's similarity coefficient was 0.66 (±0.16). Of 289 CBCT scans, tumours in 27 (90%) patients regressed by a mean (±SD) rate of 1.5% (±0.75) per fraction. The mean (±SD) GTV regression was 43.1% (±23.1) from the first to final CBCT. CONCLUSION: Primary lung tumour volumes observed on CBCT and time-matched CT are highly correlated (although not identical), thereby validating observations of GTV regression on CBCT in NSCLC.
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ItemDevelopment of a multicentre automated model to reduce planning variability in radiotherapy of prostate cancer(ELSEVIER, 2019-07)BACKGROUND AND PURPOSE: Inter-institutional studies highlighted correlation between consistent radiotherapy quality and improved overall patient survival. In treatment planning automation has the potential to address differences due to user-experience and training, promoting standardisation. The aim of this study was to evaluate implementation and clinical effect of a multicentre collaboratively-developed automated planning model for Intensity-Modulated Radiation Therapy/Volumetric-Modulated Arc Therapy of prostate. The model was built using a variety of public institutions' clinical plans, incorporating different contouring and dose protocols, aiming at minimising their variation. METHODS AND MATERIALS: A model using 110 clinically approved and treated prostate plans provided by different radiotherapy centres was built with RapidPlan (RP), for use on intact and post-prostatectomy prostate cases. The model was validated, distributed and introduced into clinical practice in all institutions. To investigate its impact a total of 126 patients, originally manually inverse planned (OP), were replanned using RP without additional planner manual intervention. Target and organ-at-risk (OAR) metrics were statistically compared between original and automated plans. RESULTS: For all centres combined and individually, RP provided plans comparable or superior to OP for all dose metrics. Statistically significant reductions with RP were found in bladder (V40Gy) and rectal (V50Gy) low doses (within 2.3% and 3.4% for combined and 4% and 10% individually). No clinically significant changes were seen for the PTV, independently of seminal vesicle inclusion. CONCLUSION: This project showed it is feasible to develop, share and implement RP models created with plans from different institutions treated with a variety of techniques and dose protocols, with the potential of improving treatment planning results and/or efficiency despite the original variability.
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ItemNo Preview AvailableSystematic endobronchial ultrasound-guided transbronchial needle aspiration improves radiotherapy planning in non-small cell lung cancer(European Respiratory Society, 2019-07)Objectives: Patients suitable for radical chemoradiotherapy for lung cancer routinely have radiotherapy (planning) volumes based on positron emission tomography (PET)-computed tomography (CT) imaging alone. Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) can identify PET-occult malignancy and benign PET-avid regions. We investigated the impact of EBUS-TBNA on curative-intent radiotherapy in non-small cell lung cancer (NSCLC). Methods: A prospective multicentre trial was undertaken, investigating the impact of systematic EBUS-TBNA in addition to PET-CT for patients considered for radical chemoradiotherapy with NSCLC. A subset analysis of patients with discordant findings between PET-CT and EBUS-TBNA was performed. Radiotherapy plans investigated tumour coverage and dose to critical organs at risk (OARs) using PET-CT alone in comparison to PET-CT and EBUS-TBNA. Results: Of 30 patients enrolled, 10 had discordant findings between PET-CT and EBUS-TBNA. EBUS-TBNA-derived plans allowed for reduction in dose to OARs in patients downstaged by EBUS-TBNA, and reduced the risk of geographic miss in treating PET-occult disease in four patients where EBUS-TBNA identified malignant involvement of PET-negative lymphadenopathy. With the addition of EBUS-TBNA to radiotherapy planning, reductions were noted of 5.7%, 3.7% and 12.5% for the risks of symptomatic pneumonitis, mean heart dose and mean oesophageal dose, respectively. Conclusions: This study demonstrates for the first time that systematic EBUS-TBNA prior to radical-intent radiotherapy significantly improves coverage of subclinical disease through detection of PET-occult metastases. Identification of false-positive lymph node involvement in highly selected cases may reduce radiation dose to critical structures, and risk of organ toxicity.