Estimate of the secondary cancer risk from megavoltage CT in tomotherapy

Dong Wook Kim, Weon Kuu Chung, Sung Hwan Ahn, Myonggeun Yoon

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


We have assessed the radiation-induced excess cancer risk to organs from megavoltage computed tomography (MVCT). MVCT was performed in coarse, normal and fine scanning modes. Using a glass dosimeter, we measured the primary and the secondary doses inside a homemade phantom and at various distances from the imaging center. The organ-specific excess absolute risk (EAR) for cancer induction was estimated using an organ-equivalent dose (OED) based on the measured imaging doses. The average primary doses inside the phantom for the coarse, normal and fine scanning modes were 0.78, 1.15 and 2.15 cGy, respectively. The average secondary dose per scan, measured 20 to 60 cm from the imaging center, ranged from 0.044 to 0.008 cGy. The EAR for major organs indicated that when 30 MVCT scans are performed to position each patient during the course of radiation treatment, organ-specific cancers may develop in as many as 6 per 10,000 persons per year.

Original languageEnglish
Pages (from-to)1199-1203
Number of pages5
JournalJournal of the Korean Physical Society
Issue number8
Publication statusPublished - 2013 Apr

Bibliographical note

Funding Information:
This research was supported by the National Nuclear R&D Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (2012M5A1A2054133) and the General Researcher Program (2012003174) through the National Research Foundation.


  • Excess cancer risk
  • Megavoltage computed tomography
  • Radiation dose

ASJC Scopus subject areas

  • General Physics and Astronomy


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