Daily Image Guidance With Cone-Beam Computed Tomography for Head-and-Neck Cancer Intensity-Modulated Radiotherapy: A Prospective Study

Robert B. Den, Anthony Doemer, Greg Kubicek, Greg Bednarz, James M. Galvin, William M. Keane, Ying Xiao, Mitchell Machtay

Research output: Contribution to journalArticlepeer-review

103 Scopus citations

Abstract

Purpose: To report on a prospective clinical trial of the use of daily kilovoltage cone-beam computed tomography (CBCT) to evaluate the interfraction and residual error motion of patients undergoing intensity-modulated radiotherapy for head-and-neck cancer. Methods and Materials: Patients were treated with intensity-modulated radiotherapy with an Elekta linear accelerator using a mounted CBCT scanner. CBCT was performed before every treatment, and translational (but not rotational) corrections were performed. At least once per week, a CBCT scan was obtained after intensity-modulated radiotherapy. Variations were measured in the medial-lateral, superoinferior, and anteroposterior dimensions, as well as in the rotation around these axes. Results: A total of 28 consecutive patients (1,013 CBCT scans) were studied. The average interfraction shift was 1.4 ± 1.4, 1.7 ± 1.9, and 1.8 ± 2.1 mm in the medial-lateral, superoinferior, and anteroposterior dimensions, respectively. The corresponding average residual error shifts were 0.7 ± 0.8, 0.9 ± 0.9, and 0.9 ± 0.9 mm. These data indicate that in the absence of daily CBCT image-guided radiotherapy, a clinical target volume to planning target volume margin of 3.9, 4.1, and 4.9 mm is needed in the medial-lateral, superoinferior, and anteroposterior dimensions, respectively. With daily CBCT, corresponding margins of 1.6, 2.5, and 1.9 mm should be acceptable. Subgroup analyses showed that larynx cancers and/or intratreatment weight loss indicate a need for slightly larger clinical target volume to planning target volume margins. Conclusion: The results of our study have shown that image-guided radiotherapy using CBCT for head-and-neck cancer is effective. These data suggest it allows a reduction in the clinical target volume to planning target volume margins by about 50%, which could facilitate future studies of dose escalation and/or improved toxicity reduction. Caution is particularly warranted for cases in which the targets are mobile (e.g., the tongue).

Original languageEnglish (US)
Pages (from-to)1353-1359
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume76
Issue number5
DOIs
StatePublished - Apr 2010

All Science Journal Classification (ASJC) codes

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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