title: Neck node bolus technique in the treatment of Nasopharyngeal Carcinoma with Intensity-modulated radiotherapy.
abstract: OBJECTIVE
  To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume with intensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  This retrospective study used data from 5 consecutive patients with NPC who were treated with bolus for large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients were treated radically with IMRT according to our institution's protocol. Re-planning with IMRT without bolus for these patients with exactly the same target volumes were done for comparison. Comparison of the plans was done by comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N.
  
  
  RESULTS
  The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. The mean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showed an absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had an advantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). The mean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only 23.5 Gy for the plans without bolus.
  
  
  CONCLUSIONS
  Neck node bolus technique should be strongly considered in the treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry compared to non-bolus plans with acceptable skin toxicity.
authors: Clinical Oncology Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. vince_phua@yahoo.com
authors: Chee Ee
authors: CE
authors: Phua
authors: Ngie Min
authors: NM
authors: Ung
authors: Boon Seang
authors: BS
authors: Tan
authors: Ai Lian
authors: AL
authors: Tan
authors: Kae Yann
authors: KY
authors: Eng
authors: Bong Seng
authors: BS
authors: Ng
mesh_terms: D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D047368:Tumor Burden