Radiation-induced cancers from modern radiotherapy techniques: Intensity-modulated radiotherapy versus proton therapy

Myonggeun Yoon, Sung Hwan Ahn, Jinsung Kim, Dong Ho Shin, Sung Yong Park, Se Byeong Lee, Kyung Hwan Shin, Kwan Ho Cho

Research output: Contribution to journalArticlepeer-review

74 Citations (Scopus)


Purpose: To assess and compare secondary cancer risk resulting from intensity-modulated radiotherapy (IMRT) and proton therapy in patients with prostate and head-and-neck cancer. Methods and Materials: Intensity-modulated radiotherapy and proton therapy in the scattering mode were planned for 5 prostate caner patients and 5 head-and-neck cancer patients. The secondary doses during irradiation were measured using ion chamber and CR-39 detectors for IMRT and proton therapy, respectively. Organ-specific radiation-induced cancer risk was estimated by applying organ equivalent dose to dose distributions. Results: The average secondary doses of proton therapy for prostate cancer patients, measured 20-60cm from the isocenter, ranged from 0.4 mSv/Gy to 0.1 mSv/Gy. The average secondary doses of IMRT for prostate patients, however, ranged between 3 mSv/Gy and 1 mSv/Gy, approximately one order of magnitude higher than for proton therapy. Although the average secondary doses of IMRT were higher than those of proton therapy for head-and-neck cancers, these differences were not significant. Organ equivalent dose calculations showed that, for prostate cancer patients, the risk of secondary cancers in out-of-field organs, such as the stomach, lungs, and thyroid, was at least 5 times higher for IMRT than for proton therapy, whereas the difference was lower for head-and-neck cancer patients. Conclusions: Comparisons of organ-specific organ equivalent dose showed that the estimated secondary cancer risk using scattering mode in proton therapy is either significantly lower than the cases in IMRT treatment or, at least, does not exceed the risk induced by conventional IMRT treatment.

Original languageEnglish
Pages (from-to)1477-1485
Number of pages9
JournalInternational Journal of Radiation Oncology Biology Physics
Issue number5
Publication statusPublished - 2010 Aug 1
Externally publishedYes


  • CR-39
  • IMRT
  • Organ equivalent dose
  • Proton
  • Secondary dose

ASJC Scopus subject areas

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


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