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Nicholas Hardcastle
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P1.14 - Radiotherapy (ID 700)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P1.14-017 - Impact of Systematic EBUS-TBNA Mediastinal Staging on Radical Radiotherapy Planning in NSCLC (ID 8497)
09:30 - 09:30 | Presenting Author(s): Nicholas Hardcastle
- Abstract
Background:
Radical radiotherapy often relies solely on radiological imaging to determine treatment volumes. Systematic mediastinal staging with endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) may identify PET-occult sites of mediastinal disease, or demonstrate benign causes for PET-positive LN. This study evaluated 1) Involved nodal coverage 2) Doses to organs-at-risk when planned based on PET-CT and EBUS-TBNA and 3) Incident dose to mediastinal nodes between 3D-CRT and Intensity-Modulated-Radiotherapy (IMRT).
Method:
Radical radiotherapy plans (60Gy/30 fractions) were created for patients with stage change following EBUS-TBNA from a prospective clinical trial. We compared lung Normal-Tissue-Complication-Probability (NTCP, pneumonitis), oesophageal and heart dose for planning to targets based on PET-CT versus PET-CT+EBUS-TBNA. The incidental dose to PET-negative/EBUS-TBNA-positive nodes from 3DCRT and IMRT was evaluated using volume receiving 35Gy as a surrogate for control of sub-clinical disease (Kepka, IJROBP, 73(5) 2009).
Result:
Of 30 patients enrolled, four were upstaged by EBUS-TBNA; these patients had a significant geographic miss of nodal GTV when planned to PET-positive nodes only (Figure 1). When planned based on PET-CT alone, the incidental dose to PET-negative/EBUS-TBNA-positive nodes was higher with IMRT for two patients (v35Gy increased by 17% & 6%; Figure 1a&b) and lower with IMRT (v35Gy reduced by 16% and 6%; Figure 1c&d) for two, dependent on nodal position relative to the primary. Six patients had negative pathology for PET avid nodal stations; Inclusion of EBUS-negative, PET-positive nodes resulted in an average increased lung NTCP of 5% (range 1%-13%), mean oesophagus dose of 13Gy (range 4-23Gy) and mean heart dose of 4Gy (range -0.1-11Gy) over plans based on EBUS-positive nodes alone. Figure 1
Conclusion:
Systematic EBUS-TBNA has the potential to improve loco-regional control and limit the probability of lung and heart toxicity. The incidental dose to adjacent tissue is inherently related to involved node/tumour position and not solely dictated by the radiation delivery technique.
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P2.05 - Early Stage NSCLC (ID 706)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Early Stage NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P2.05-006 - Credentialing of Radiotherapy Centres in Australasia for a Phase III Clinical Trial on SABR (TROG 09.02 CHISEL) (ID 9985)
09:30 - 09:30 | Presenting Author(s): Nicholas Hardcastle
- Abstract
Background:
A randomised phase III clinical trial comparing Stereotactic Ablative Body Radiotherapy (SABR) with conventional radiotherapy for early stage lung cancer in peripheral location has been conducted in Australia and New Zealand under the auspices of the Trans Tasman Radiation Oncology Group (TROG). As SABR technology at the commencement of the trial was new to most centres in our region and the techniques used are complex and technologically challenging a credentialing program was developed for centres wishing to join the trial.
Method:
The credentialing program used a prospective risk management approach with high risk elements considered to be (i) the ability to create a plan that meets all dosimetric constraints, (ii) the dose calculation in the presence of inhomogeneities and (iii) the management of motion. Participating centres were asked to develop treatment plans for two test cases made available in DICOM format, and inhomogeneity corrections and dose delivery was assessed during a site visit using a phantom with moving inserts (modified Modus Quasar).
Result:
Site visits were conducted in 17 Australian and 3 New Zealand radiotherapy facilities. All centres were able to produce acceptable plans for both test cases, in particular after the protocol was amended to allow delivery of 48Gy in 4 fractions for lesions close to the chest wall in addition to the original trial arm of 54Gy in 3 fractions. The tests conducted during site visit with lung and air inhomogenieties confirmed known shortcomings of the AAA algorithm for dose calculation behind the inhomogeneity. The dose was assessed using an ionisation chamber and radiochromic film in a stationary and moving cylinder (sinusoidal motion, 1cm amplitude, 4s period) in the phantom for a typical treatment delivery including at least one non-coplanar beam. The measurements confirmed in an end-to-end test that all participating centres were able to deliver SABR with the required accuracy. Overall, the site visit took 3 hours of time on the treatment unit and was well received by participating staff. For several facilities it proved to be a useful step in the process of developing a SABR program.
Conclusion:
The credentialing process including a site visit documented that participating centres were able to deliver dose to a phantom as required in the trial protocol. It also gave an opportunity to provide education about the trial and discuss technical issues such as 4D CT, small field dosimetry and patient immobilisation with staff in participating centres.
