Clinical delivery of intensity modulated conformal radiotherapy for relapsed or second-primary head and neck cancer using a multileaf collimator with dynamic control

Wilfried De Neve, Wezner De Gersem, Sylvie Derycke, Gert De Meerleer, Mieke Moerman, Marie Thélèse Bate, Bart Van Duyse, Luc Vakaet, Yves De Deene, Bart Mersseman, Carlos De Waeter

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84 Citations (Scopus)

Abstract

Background and purpose: Concave dose distributions generated by intensity modulated radiotherapy (IMRT) were applied to re-irradiate three patients with pharyngeal cancer. Patients, materials and methods: Conventional radiotherapy for oropharyngeal (patients 1 and 3) or nasopharyngeal (patient 2) cancers was followed by relapsing or new tumors in the nasopharynx (patients 1 and 2) and hypopharynx (patient 3). Six non- opposed coplanar intensity modulated beams were generated by combining non- modulated beamparts with intensities (weights) obtained by minimizing a biophysical objective function. Beamparts were delivered by a dynamic MLC (Elekta Oncology Systems, Crawley, UK) forced in step and shoot mode. Results and conclusions: Median PTV-doses (and ranges) for the three patients were 73 (65-78), 67 (59-72) and 63 (48-68) Gy. Maximum point doses to brain stem and spinal cord were, respectively, 67 Gy (60% of volume below 30 Gy) and 32 Gy (97% below 10 Gy) for patient 1:60 Gy (69% below 30 Gy) and 34 Gy (92% below' 10 Gy) for patient 2 and 21 Gy (96% below 10 Gy) at spinal cord for patient 3. Maximum point doses to the mandible were 69 Gy for patient 1 and 64 Gy for patient 2 with, respectively, 66 and 92% of the volume below 20 Gy. A treatment session, using the dynamic MLC, was finished within a 15-min time slot.

Original languageEnglish
Pages (from-to)301-314
Number of pages14
JournalRadiotherapy and Oncology
Volume50
Issue number3
DOIs
Publication statusPublished - 1 Mar 1999
Externally publishedYes

Bibliographical note

Erratum can be found in Radiotherapy and Oncology, 52(1), p. 89, 1999.
https://doi.org/10.1016/S0167-8140(99)00092-4

Keywords

  • Dosimetry
  • Intensity modulation
  • Multileaf collimators
  • Step and shoot

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