Dosimetric Comparison of Intensity-Modulated Stereotactic Radiotherapy With Other Stereotactic Techniques for Locally Recurrent Nasopharyngeal Carcinoma

Journal Article · Sat Jan 01 04:00:00 EST 2011 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.10.044· OSTI ID:21491539

Kung, Shiris Wai Sum ^[1]; Wu, Vincent Wing Cheung ^[2]; Leung, Sing Fai; Yu, Brian Kwok Hung; Ngai, Dennis Yuen Kan; Wong, Simon Chun Fai; Chan, Anthony Tak Cheung ^[1]

---

1. State Key Laboratory in Oncology in South China, Sir Y. K. Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute, Prince of Wales Hospital, Chinese University of Hong Kong (Hong Kong)
2. Department of Health Technology and Informatics, Hong Kong Polytechnic University (Hong Kong)

Purpose: Locally recurrent nasopharyngeal carcinoma (NPC) patients can be salvaged by reirradiation with a substantial degree of radiation-related complications. Stereotactic radiotherapy (SRT) is widely used in this regard because of its rapid dose falloff and high geometric precision. The aim of this study was to examine whether the newly developed intensity-modulated stereotactic radiotherapy (IMSRT) has any dosimetric advantages over three other stereotactic techniques, including circular arc (CARC), static conformal beam (SmMLC), and dynamic conformal arc (mARC), in treating locally recurrent NPC. Methods and Materials: Computed tomography images of 32 patients with locally recurrent NPC, previously treated with SRT, were retrieved from the stereotactic planning system for contouring and computing treatment plans. Treatment planning of each patient was performed for the four treatment techniques: CARC, SmMLC, mARC, and IMSRT. The conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV) and doses to the organs at risk (OARs) and normal tissue were compared. Results: All four techniques delivered adequate doses to the PTV. IMSRT, SmMLC, and mARC delivered reasonably conformal and homogenous dose to the PTV (CI <1.47, HI <0.53), but not for CARC (p < 0.05). IMSRT presented with the smallest CI (1.37) and HI (0.40). Among the four techniques, IMSRT spared the greatest number of OARs, namely brainstem, temporal lobes, optic chiasm, and optic nerve, and had the smallest normal tissue volume in the low-dose region. Conclusion: Based on the dosimetric comparison, IMSRT was optimal for locally recurrent NPC by delivering a conformal and homogenous dose to the PTV while sparing OARs.

• OSTI ID: 21491539
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 1 Vol. 79; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BODY
CARCINOMAS
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DIGESTIVE SYSTEM
DISEASES
DOSES
IMAGES
MEDICINE
NEOPLASMS
NUCLEAR MEDICINE
ORGANS
PHARYNX
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
RESPIRATORY SYSTEM
THERAPY
TOMOGRAPHY