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MO23 - Radiotherapy II: Lung Toxicity, Target Definition and Quality Assurance (ID 107)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Radiation Oncology + Radiotherapy
- Presentations: 1
MO23.08 - Inter-observer Variability in Gross Tumour Volume Delineation on Kilo-voltage Cone Beam Computed Tomography (CBCT) Scans for Lung Cancer Radiotherapy Treatment Verification (ID 3294)
10:30 - 12:00 | Author(s): S.K. Vinod
The use of CBCT is essential for precise treatment delivery of radiotherapy for lung cancer. The current work practice at many centres is to use bony landmarks to match on-treatment CBCT to the radiotherapy planning CT to verify treatment. To take full advantage of this imaging modality for lung cancer, soft-tissue matching is preferred as it ensures that the actual lung cancer is within the radiotherapy fields regardless of bony anatomy. However Radiation Therapists (RTs) are trained in bony matching and not soft tissue matching. The purpose of this study was to determine the level of inter-observer variability in lung cancer gross tumour volume (GTV) delineation on CBCT and alignment of the CBCT with a planning GTV between Radiation Therapists (RTs), a Radiation Oncologist (RO) and a Radiologist (RD)
Ten RTs, one RO and one RD independently delineated the lung cancer GTV for fifteen lung cancer patients on Elekta Synergy CBCT image datasets taken on the first treatment fraction. The window and level settings used by each observer were recorded. Each observer then performed an alignment of the CBCT GVT to the radiotherapy planning GTV and translational errors were recorded. The difference in the isocentre corrections for the alignment shifts and Centre of Volume, Volume and Concordance Index (CI) for the contoured volumes were calculated to determine the level of agreement between the RT’s and the RD and between the RTs and the RO, in comparison to the variation between the RD and RO. In an ideal setting the difference between the RTs and the RO and the RTs and the RD would be at least equivalent to the difference between the RD and RO.
The difference between the RT’s and RO and RD was found to be not statistically equivalent to the difference between the RD and RO. The mean isocentre difference between the RO and RD was 0.40cm, compared with 0.42cm and 0.51cm between the RT’s and the RO and RD respectively. The mean CI between the RD and RO was 0.56 (0.44,0.69), which was smaller than the lower bound of the 95 % confidence intervals (95%) of the RT’s compared to the RD (0.5, 0.56) and RO (0.52,0.59). The mean log COV difference was -0.82cm between the RD and RO and -0.54 and -0.65cm between the RT’s and RO and RD respectively. The volume results showed that only 6 of thirty comparisons were equivalent. The mean volume difference between the RD and RO was 0.44cm and 4.73 cm and 5.7cm between the RT’s and RO and RD respectively.
The variation between the RTs and the RO and RD was greater than the variation between the RO and RD. Advanced training is necessary to educate the RTs on soft-tissue matching on CBCT for lung cancer radiotherapy.
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P1.09 - Poster Session 1 - Combined Modality (ID 212)
- Event: WCLC 2013
- Type: Poster Session
- Track: Combined Modality
- Presentations: 1
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
P1.09-020 - Clinical guideline adherence in locally advanced non-small cell lung cancer: A south western Sydney perspective (ID 3171)
09:30 - 16:30 | Author(s): S.K. Vinod
Stage III non-small cell lung cancer (NSCLC) typically represents up to one third of all new NSCLC diagnoses, and can be a technically difficult and controversial group of patients to definitively manage. In 2004, the National Health and Medical Research Council published a set of evidence based clinical guidelines for the management of lung cancer in Australia. This study aims to investigate adherence to these national guidelines in the treatment of Stage III cancers and identify factors associated with the receipt of guideline recommended therapy (GRT) and patient survival.
A retrospective cohort of newly diagnosed, Stage III NSCLC was identified from the South Western Sydney (SWS) Local Health District Clinical Cancer Registry. Cases were diagnosed between 2006 and 2011 and resided within SWS local postcode boundaries. Pre-2010 diagnosed “wet” stage IIIB cases with malignant pleural effusion were excluded from analysis. GRT was assigned to each case based on stage group and performance status (ECOG) at diagnosis. Significant factors associated with adherence to GRT and the effect these factors had on patient survival was determined using univariate analysis and Cox proportional hazards regression model.
Of 316 eligible cases identified, 19 patients (6%) had no ECOG documentation found, and were excluded from the analysis. Median age of the remaining cohort was 69 years, and 64% were male. Disease stage distribution was 58% for IIIA cases and 42% for IIIB. 85% of patients were identified as having Good ECOG (0-2) at diagnosis. Overall 55% of the total; 63% of IIIA and 46% of IIIB patients received GRT. 24% of IIIA patients received surgery alone in combination with chemotherapy and/or radiotherapy. 31% of IIIB patients received either concurrent or combination chemo-radiation. On univariate analysis, the receipt of GRT was associated with patient age (p <0.001), disease stage (p 0.003), and performance status (p <0.001). Morphological subtype was trending (p 0.056). Overall median survival was 11.4 months. Patient survival was not significantly improved with the receipt of GRT.
Adherence to GRT was associated with tumour stage, patient age and performance status. In this cohort of patients, the receipt of GRT did not have a significant impact on survival.