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A hybrid approach for head and neck cancer using online image guidance and offline adaptive radiotherapy planning

  • Roopam Srivastava (a1), P.K. Sharma (a1), K.J. Maria Das (a2) and Jayanand Manjhi (a3)
Abstract
Background

This is a prospective study to evaluate the dosimetric benefits of treatment plan adaptation for patients who had undergone repeat computed tomography (ReCT)and re-planning due to treatment-induced anatomical changes during radiotherapy.

Materials and Methods

This study involved five head and neck cancer patients who had their treatment plan modified, based on weekly thrice imaging protocol. Impact of mid-course imaging was assessed in patients using ReCT and cone beam computed tomography (CBCT)-based dose verification. Patients were imaged, apart from their initial CT, during the course of their radiation therapy with a ReCT and on board imager CBCT (Varian Medical Systems Inc., Palo Alto, CA, USA). Each CBCT/CT series was rigidly registered to the initial CT in the treatment planning system Eclipse (Varian Medical Systems Inc.) using bony landmarks. The structures were copied to the current CBCT/CT series and, where needed, manually edited slicewise. The dose distribution from the treatment plan was viewed as of the current anatomy by applying the treatment plan the CBCT/CT series, and studying the corresponding dose–volume histograms for organs at risk doses.

Results

The reduction of parotid volumes due to weight loss was observed in all patients, which means an increase in predicted mean doses of parotid when initial CT plan was re-calculated on ReCT and CBCT (Table 1). This explains the necessity of adaptive planning. The predicted mean dose of parotid glands was increased and constraints to spinal cord and skin were exceeded, so re-planning was performed.

Conclusions

The CBCT is a useful tool to view anatomic changes in patients and get an estimate of their impact on dose distribution. Re-planning based on imaging in head and neck patients during the course of radiotherapy is mandatory to reduce side effects.

Copyright
Corresponding author
Author for correspondence: Roopam Srivastava, Department of Medical Physics and Radiation Safety, International Oncology Centre, Fortis Hospital, Noida, Uttar Pradesh, India. E-mail: roopam22sep@gmail.com
Footnotes
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Cite this article: Srivastava R, Sharma PK, Das KJM, Manjhi J. (2019) A hybrid approach for head and neck cancer using online image guidance and offline adaptive radiotherapy planning. Journal of Radiotherapy in Practice page 1 of 5. doi: 10.1017/S146039691800078X

Footnotes
References
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Journal of Radiotherapy in Practice
  • ISSN: 1460-3969
  • EISSN: 1467-1131
  • URL: /core/journals/journal-of-radiotherapy-in-practice
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