Practically acquired and modified cone-beam computed tomography images for accurate dose calculation in head and neck cancer

Chih Chung Hu, Wen Tao Huang, Chiao Ling Tsai, Jian Kuen Wu, Hsiao Ling Chao, Guo Ming Huang, Chun Wei Wang, Chien Jang Wu, Jason Chia Hsien Cheng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Background: On-line cone-beam computed tomography (CBCT) may be used to reconstruct the dose for geometric changes of patients and tumors during radiotherapy course. This study is to establish a practical method to modify the CBCT for accurate dose calculation in head and neck cancer. Patients and Methods: Fan-beam CT (FBCT) and Elekta's CBCT were used to acquire images. The CT numbers for different materials on CBCT were mathematically modified to match them with FBCT. Three phantoms were scanned by FBCT and CBCT for image uniformity, spatial resolution, and CT numbers, and to compare the dose distribution from orthogonal beams. A Rando phantom was scanned and planned with intensity-modulated radiation therapy (IMRT). Finally, two nasopharyngeal cancer patients treated with IMRT had their CBCT image sets calculated for dose comparison. Results: With 360° acquisition of CBCT and high-resolution reconstruction, the uniformity of CT number distribution was improved and the otherwise large variations for background and high-density materials were reduced significantly. The dose difference between FBCT and CBCT was < 2% in phantoms. In the Rando phantom and the patients, the dose-volume histograms were similar. The corresponding isodose curves covering ≥ 90% of prescribed dose on FBCT and CBCT were close to each other (within 2 mm). Most dosimetric differences were from the setup errors related to the interval changes in body shape and tumor response. Conclusion: The specific CBCT acquisition, reconstruction, and CT number modification can generate accurate dose calculation for the potential use in adaptive radiotherapy.

Original languageEnglish
Pages (from-to)633-644
Number of pages12
JournalStrahlentherapie und Onkologie
Issue number10
Publication statusPublished - 2011 Oct


  • Cone-beam computed tomography
  • Dose calculation
  • Head and neck cancer
  • Linear accelerator
  • Radiotherapy

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Oncology


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