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Current Oncology
Volume 13
Issue 3
10.3390/curroncol13030010
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Current Oncology is published by MDPI from Volume 28 Issue 1 (2021). Previous articles were published by another publisher in Open Access under a CC-BY (or CC-BY-NC-ND) licence, and they are hosted by MDPI on mdpi.com as a courtesy and upon agreement with Multimed Inc..
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Article

Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume

by
O. Ballivy
1,
W. Parker
1,2,*,
T. Vuong
1,
G. Shenouda
1 and
H. Patrocinio
1,2
1
Division of Radiation Oncology, Department of Oncology, McGill University, Montreal, Quebec, Canada
2
Medical Physics Unit, Department of Oncology, McGill University, Montreal, Quebec, Canada
*
Author to whom correspondence should be addressed.
Curr. Oncol. 2006, 13(3), 108-115; https://doi.org/10.3390/curroncol13030010
Submission received: 1 March 2006 / Revised: 5 April 2006 / Accepted: 3 May 2006 / Published: 1 June 2006
Versions Notes

Abstract

We assessed the effect of geometric uncertainties on target coverage and on dose to the organs at risk (OARS) during intensity-modulated radiotherapy (IMRT) for head-and-neck cancer, and we estimated the required margins for the planning target volume (PTV) and the planning organ-at-risk volume (PRV). For eight headand- neck cancer patients, we generated IMRT plans with localization uncertainty margins of 0 mm, 2.5 mm, and 5.0 mm. The beam intensities were then applied on repeat computed tomography (CT) scans obtained weekly during treatment, and dose distributions were recalculated. The dose–volume histogram analysis for the repeat CT scans showed that target coverage was adequate (V100 ≥ 95%) for only 12.5% of the gross tumour volumes, 54.3% of the upper-neck clinical target volumes (CTVS), and 27.4% of the lower-neck CTVS when no margins were added for PTV. The use of 2.5-mm and 5.0-mm margins significantly improved target coverage, but the mean dose to the contralateral parotid increased from 25.9 Gy to 29.2 Gy. Maximum dose to the spinal cord was above limit in 57.7%, 34.6%, and 15.4% of cases when 0-mm, 2.5-mm, and 5.0-mm margins (respectively) were used for PRV. Significant deviations from the prescribed dose can occur during IMRT treatment delivery for headand- neck cancer. The use of 2.5-mm to 5.0-mm margins for PTV and PRV greatly reduces the risk of underdosing targets and of overdosing the spinal cord.
Keywords: imrt; ptv margins; head and neck; geometric uncertainties; 3D crt imrt; ptv margins; head and neck; geometric uncertainties; 3D crt

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MDPI and ACS Style

Ballivy, O.; Parker, W.; Vuong, T.; Shenouda, G.; Patrocinio, H. Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume. Curr. Oncol. 2006, 13, 108-115. https://doi.org/10.3390/curroncol13030010

AMA Style

Ballivy O, Parker W, Vuong T, Shenouda G, Patrocinio H. Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume. Current Oncology. 2006; 13(3):108-115. https://doi.org/10.3390/curroncol13030010

Chicago/Turabian Style

Ballivy, O., W. Parker, T. Vuong, G. Shenouda, and H. Patrocinio. 2006. "Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume" Current Oncology 13, no. 3: 108-115. https://doi.org/10.3390/curroncol13030010

APA Style

Ballivy, O., Parker, W., Vuong, T., Shenouda, G., & Patrocinio, H. (2006). Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume. Current Oncology, 13(3), 108-115. https://doi.org/10.3390/curroncol13030010

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