Dosimetric Evaluation of a Simple Planning Technique for Improving Intensity-Modulated Radiotherapy for Nasopharyngeal Cancer

PLoS One. 2015 Jul 1;10(7):e0129461. doi: 10.1371/journal.pone.0129461. eCollection 2015.

Abstract

Purpose: To evaluate the dosimetric outcomes of a simple planning technique for improving intensity-modulated radiotherapy (IMRT) for nasopharyngeal cancer (NPC).

Methods: For 39 NPC cases, generally acceptable original plans were generated and were improved by the two planning techniques, respectively: (1) a basal-dose-compensation (BDC) technique, in which the treatment plans were re-optimized based on the original plans; (2) a local-dose-control (LDC) technique, in which the original plans were re-optimized with constraints for hot and cold spots. The BDC, original, and LDC plans were then compared regarding homogeneity index (HI) and conformity index (CI) of planning target volumes (PTVs), organ-at-risk (OAR) sparing and monitor units (MUs) per fraction. The whole planning times were also compared between the BDC and LDC plans.

Results: The BDC plans had superior HIs / CIs, by 13-24% / 3-243%, respectively, over the original plans. Compared to the LDC plans, the BDC plans provided better HIs only for PTVnx (the PTV of nasopharyngeal primary tumor) by 11% and better CIs for all PTVs by 2-134%. The BDC technique spared most OARs, by 1-9%. The average MUs of the BDC, original, and LDC plans were 2149, 2068 and 2179, respectively. The average whole planning times were 48 and 69 minutes for the BDC and LDC plans, respectively.

Conclusions: For the IMRT of nasopharyngeal cancer, the BDC planning technique can improve target dose homogeneity, conformity and OAR sparing, with better planning efficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Carcinoma
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / diagnosis
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Planning Techniques
  • Radiometry
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted*
  • Radiotherapy, Intensity-Modulated* / methods
  • Tomography, X-Ray Computed
  • Young Adult

Grants and funding

This work was sponsored in part by both National Natural Science Foundation of China (Grant No. 81171994) and Shantou University Medical College Clinical Research Enhancement Initiative (Grant No. 201425). The authors’ also acknowledge support from the German Research Foundation and the Open Access Publication Funds of the TU Dresden. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.