Development and QA of IGRT procedures for node-positive prostate cancer patients in the PEARLS trial
Olivia Naismith,
United Kingdom
OC-0421
Abstract
Development and QA of IGRT procedures for node-positive prostate cancer patients in the PEARLS trial
Authors: Olivia Naismith1, Sophie Alexander2,3, Amanda Webster4, Elizabeth Miles5, Shama Hassan6, Julia Murray7,8
1Radiotherapy Trials QA Group (RTTQA), The Royal Marsden NHS Foundation Trust, London, United Kingdom; 2Radiotherapy Trials QA Group (RTTQA), The Royal Marsden NHS Foundation Trust, Sutton, United Kingdom; 3The Institute of Cancer Research, Radiotherapy, Sutton, United Kingdom; 4Radiotherapy Trials QA Group (RTTQA), University College London Hospital (UCLH), London, United Kingdom; 5Radiotherapy Trials QA Group (RTTQA), Mount Vernon Hospital, Northwood, United Kingdom; 6The Institute of Cancer Research, Clinical Trials and Statistics Unit, Sutton, United Kingdom; 7The Royal Marsden NHS Foundation Trust, Radiotherapy, Sutton, United Kingdom; 8The Institute of Cancer Research, Clinical Oncology, Sutton, United Kingdom
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Purpose or Objective
PEARLS (ISRCTN 36344989; CRUK/19/016) is a multicentre randomised Phase II/III trial for node-positive prostate cancer. The experimental arm gives extended field IMRT to the prostate, pelvis (PP) and para-aortic (PPP) region, with an integrated boost to involved lymph nodes.
Treating this cohort of patients is new for many RTTs. Image verification must consider both prostate and nodal targets, however, this is complicated by motion of the prostate independent of bony anatomy. Comprehensive IGRT guidance and an innovative QA programme were therefore developed to support implementation of the trial.
This work presents QA initiatives, investigates the range of IGRT and immobilisation, with an interim review of initial patients treated in the trial.
Material and Methods
IGRT guidance was developed with multi-disciplinary input from a range of UK centres, and considered multiple treatment and imaging platforms. For PP/PPP arm patients it included management of deviations between prostate and bone (a surrogate for nodal targets) with threshold limits set (≤5 mm; >5 mm but ≤10 mm; >10 mm) for escalation.
A pre-trial facility questionnaire (FQ) was sent to all centres enrolled to participate in the trial. The FQ assessed the centres’ experience of prostate IGRT. A novel approach was the introduction of IGRT workshops and one-to-one sessions to share experiences and agree procedures. An IGRT verification log was developed to collect setup deviation information for all recruited PP/PPP patients.
Results
15 centres are open and actively delivering treatment, and another 18 are progressing with QA.
Interim QA results from 18 centres and the RT delivery feasibility from 28 patients are reported. 2 IGRT workshops were well attended by >100 people; 5 centres had one-to-one sessions with the QA team.
PPP IGRT techniques from the first 18 centres’ FQ submissions are summarised in Figure 1.
For the first 28 PP/PPP patients treated in PEARLS, radiotherapy was successfully delivered with no re-plans required. Table 1 presents IGRT verification log results.
Fewer than 1% (4/560) of fractions had a prostate/nodes deviation >10 mm, which was corrected in all cases by an intervention before treatment delivery. Of the fractions delivered, 5.9% had a deviation of >5 mm to ≤10 mm and 94.1% were ≤5 mm. The difference in the results for PPP and PP treatments was small.
Only 29/560 fractions required a re-setup and, of these, 25 were due to patient positioning or anatomy (e.g. pelvic pitch, rectal gas).
Conclusion
The QA initiatives implemented have supported centres in delivering the treatment required for the trial. The IGRT log results provided reassurance in the quality of the IGRT guidance, independent of equipment type, and that prostate and para-aortic nodes radiotherapy can be accurately delivered.