Potential dosimetric benefit of an adaptive plan selection strategy for short-course radiotherapy in rectal cancer patients

Abstract Purpose An adaptive plan selection strategy can account for daily target volume variations for radiotherapy in rectal cancer patients. The aim was to quantify the daily dosimetric consequences of plan selection compared to a non-adaptive approach. Materials and methods Ten patients with rec...

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Published in:Radiotherapy and oncology 2016-06, Vol.119 (3), p.525-530
Main Authors: Lutkenhaus, Lotte J, de Jong, Rianne, Geijsen, Elisabeth D, Visser, Jorrit, van Wieringen, Niek, Bel, Arjan
Format: Article
Language:English
Subjects:
Adaptive radiotherapy
Adult
Aged
Aged, 80 and over
Cone-Beam Computed Tomography
Female
Hematology, Oncology and Palliative Medicine
Humans
Male
Middle Aged
Normal tissue sparing
Organs at Risk
Plan selection
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted - methods
Rectal cancer
Rectal Neoplasms - diagnostic imaging
Rectal Neoplasms - pathology
Rectal Neoplasms - radiotherapy
Short-course treatment
Tumor Burden
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Summary:Abstract Purpose An adaptive plan selection strategy can account for daily target volume variations for radiotherapy in rectal cancer patients. The aim was to quantify the daily dosimetric consequences of plan selection compared to a non-adaptive approach. Materials and methods Ten patients with rectal cancer, treated with 25 Gy in five fractions to the mesorectum and pelvic lymph nodes, were selected. The adaptive strategy was simulated by creating three plans per patient, with varying upper ventral PTV margins, and selecting the smallest PTV covering the entire mesorectum on every daily CBCT scan. Subsequently, mesorectum, bladder, and bowel cavity were delineated on these scans. Daily dose–volume histograms were calculated for both the adaptive and non-adaptive plan, with a ventral PTV margin of 20 mm. Coverage of the mesorectum, defined as V95% > 99%, was calculated, as well as bladder and bowel cavity V95% and V15Gy. Results In one patient, mesorectum coverage improved. A reduction in bladder V95% and bowel cavity V15Gy was found, of 6.9% and 18.4 cm3 ( p < 0.01), respectively. Conclusion Plan selection for radiotherapy in rectal cancer can improve coverage of the target volume. Overall dosimetric sparing of bladder and bowel cavity was limited but could be beneficial for individual patients.
ISSN:0167-8140
1879-0887
DOI:10.1016/j.radonc.2016.04.018