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MINI 18 - Radiation Topics in Localized NSCLC (ID 139)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Localized Disease - NSCLC
- Presentations: 1
MINI18.07 - Early Results of a Quality Assurance Program in a Randomized Trial of Stereotactic Body Radiotherapy for Stage I Medically Inoperable Lung Cancer (ID 2887)
16:45 - 18:15 | Author(s): J. Julian
A large Canadian multicentre randomized trial (LUSTRE) has recently opened to determine if stereotactic body radiotherapy (SBRT) to 48 Gy in 4 fractions (peripheral) or 60 Gy in 8 fractions (central) improves outcomes compared to conventionally hypofractionated radiotherapy (CRT) to 60 Gy in 15 fractions in early stage non-small cell lung cancer. Given the rapid diffusion of lung SBRT technology across Canada, a unique radiotherapy quality assurance (RTQA) program was devised to minimize variations in practice. This study describes the RTQA experience to date.
Centres participating in LUSTRE are required to satisfy three RTQA requirements prior to being accredited: (a) Respond to a survey describing treatment equipment, planning system details and image guidance parameters in order to confirm that their centre is compliant with protocol guidelines; (b) Assess SBRT delivery accuracy using a thoracic phantom produced by IROC (Imaging and Radiation Oncology Core); and (c) Successfully complete four treatment plans from the developed trial planning guide using SBRT and CRT for one centrally and one peripherally located cancer.
Currently 13 centres are undergoing RTQA: (a) Surveys have been completed in 8 centres, 2 require revision, and 3 are incomplete. (b) Phantom testing has been completed in 9 centres, 2 are incomplete, 1 has results pending, and 1 is being resubmitted. Although 6/13 centres were identified as having active SBRT programs (>3 patients/month), only 2/6 had completed the IROC phantom prior to study accreditation (most having in-house end-to-end tests). (c) 8/13 centres have successfully submitted their test cases. All 8 submitting centres passed on SBRT/CRT distributions and conformality indices. However, 5/8 centres required resubmission for contouring revisions. In one case, the GTV/ITV was incorrectly contoured. In another case, it was contoured on the incorrect dataset. In the remainder, normal organs (lungs, bronchi, esophagus) had contouring errors, particularly the bronchial tree; contours excluded the major bronchi, and in 2 cases, normal lung parenchyma was included. Some centres did not follow standardized nomenclature for targets and normal organs, as they were likely new to this naming convention. Some issues were related to misinterpretation of the planning guide, prompting the trial group to work with centres to ensure a seamless future workflow.
Preliminary results show that most well-established lung SBRT centres rely on their own in-house standards, while others are using LUSTRE RTQA to implement new SBRT programs. Our experience shows that when centres participate in an independent review, alterations are recommended that can improve their own existing QA processes, and contribute to standardized practice nationwide. Such an RTQA process can be a model worth considering in future radiotherapy randomized trials, and also when instituting new radiotherapy technologies into existing clinical programs.
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