The potential clinical benefit of respiratory gated radiotherapy (RGRT) in non-small cell lung cancer (NSCLC).
BACKGROUND
There is a great deal of excitement regarding respiratory gated radiotherapy (RGRT), however there remain potential errors and controversies surrounding its use. We aim to predict an improvement in the clinical outcome of RGRT in comparison with that of continuous (non-gated) irradiation by analysing toxicity parameters.


METHODS
The 4DCT scans of 15 patients, with node-positive lung cancer and > 5 mm of tumour movement, were used for this retrospective analysis. End-inspiration and end-expiration plans were created and the toxicity parameters were compared to continuous (non-gated) 4DCT plans.


RESULTS
Median reduction in V20 with inspiratory gating and expiratory gating, using a 10mm set-up margin, was 2.0% (range 0.7% to 3.9%) and 0.6% (range -1.1% to 4.7%), respectively. The reduction in MLD was 2.1 Gy (range 0.6 to 3.9 Gy) and 1.6 Gy (range -1.0 to 3.9 Gy), respectively.


CONCLUSIONS
Although there is a widespread excitement regarding this technique, this study demonstrates that there is limited reduction in toxicity parameters with the use of RGRT in comparison with continuous (non-gated) 4DCT irradiation. Due to the additional potential errors involved in RGRT, we feel that currently, it should only be performed if comparative planning of RGRT plans and continuous (non-gated) 4DCT plans has been undertaken and a likely clinical benefit has been confirmed.
The Beatson, West of Scotland Cancer Centre, Glasgow, United Kingdom. rebecca.muirhead@ggc.scot.nhs.uk
Rebecca
R
Muirhead
Carolyn
C
Featherstone
Aileen
A
Duffton
Karen
K
Moore
Stuart
S
McNee
D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D008297:Male; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D015656:Respiratory Mechanics; D012189:Retrospective Studies; D016896:Treatment Outcome