skip to main content

Title: Optimizing Collimator Margins for Isotoxically Dose-Escalated Conformal Radiation Therapy of Non-Small Cell Lung Cancer

Purpose: Isotoxic dose escalation schedules such as IDEAL-CRT [isotoxic dose escalation and acceleration in lung cancer chemoradiation therapy] (ISRCTN12155469) individualize doses prescribed to lung tumors, generating a fixed modeled risk of radiation pneumonitis. Because the beam penumbra is broadened in lung, the choice of collimator margin is an important element of the optimization of isotoxic conformal radiation therapy for lung cancer. Methods and Materials: Twelve patients with stage I-III non-small cell lung cancer (NSCLC) were replanned retrospectively using a range of collimator margins. For each plan, the prescribed dose was calculated according to the IDEAL-CRT isotoxic prescription method, and the absolute dose (D{sub 99}) delivered to 99% of the planning target volume (PTV) was determined. Results: Reducing the multileaf collimator margin from the widely used 7 mm to a value of 2 mm produced gains of 2.1 to 15.6 Gy in absolute PTV D{sub 99}, with a mean gain ± 1 standard error of the mean of 6.2 ± 1.1 Gy (2-sided P<.001). Conclusions: For NSCLC patients treated with conformal radiation therapy and an isotoxic dose prescription, absolute doses in the PTV may be increased by using smaller collimator margins, reductions in relative coverage being offset by increases in prescribed dose.
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7] ; ;  [6] ;  [1] ;  [2]
  1. Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom)
  2. (United Kingdom)
  3. William Buckland Radiotherapy Centre, Alfred Hospital, Commercial Road, Melbourne (Australia)
  4. Oxford Cancer Centre, Oxford University Hospitals, Oxford (United Kingdom)
  5. Velindre Cancer Centre, Velindre Road, Whitchurch, Cardiff (United Kingdom)
  6. Clatterbridge Cancer Centre, Clatterbridge Road, Wirral (United Kingdom)
  7. Department of Radiotherapy, Guy's and St. Thomas' NHS Foundation Trust, London (United Kingdom)
Publication Date:
OSTI Identifier:
22416531
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 88; Journal Issue: 5; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; COLLIMATORS; LUNGS; NEOPLASMS; OPTIMIZATION; PATIENTS; PLANNING; PNEUMONITIS; RADIATION DOSES; RADIOTHERAPY; SAFETY MARGINS; SCHEDULES