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Dosimetric and radiobiological evaluation of four radiation techniques in preoperative rectal cancer radiotherapy

Dosimetric and radiobiological evaluation of four radiation techniques in preoperative rectal... Abstract Purpose: To compare tumour dose distribution, conformality, homogeneity, normal tissue avoidance, tumour control probability (TCP) and normal tissue complication probability (NTCP) using 3D conformal radiation therapy (3DCRT), 3- and 4-field intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with locally advanced rectal cancer. Materials and methods: Twenty-four patients staged T 1–3 N + M 0 with locally advanced rectal cancer underwent neoadjuvant chemoradiation therapy. Four different radiotherapy plans were prepared for each patient: 3DCRT, 3- and 4-field IMRT and VMAT are evaluated for target distribution using CI and homogeneity index (HI), normal tissue avoidance using D max, V 45, V 40, V 50 and TCP and NTCP using the Lyman–Kutcher–Burman model. Results: VMAT has better HI (HI = 1·32) and 3DCRT exhibited better conformality (CI = 1·05) than the other radiotherapy techniques. With regard to normal tissue avoidance, all radiotherapy plans met the constraints. D max in the 3DCRT plans was statistically significant (p = 0·04) for bladder and no significant differences in V 40 and V 50. In the bowel bag, no significant differences in D max for any radiotherapy plan and V 40 was lower in 3DCRT than VMAT (p = 0·024). In the case of femoral heads, 3DCRT has a statistically significant lower dose on D max than 4-field IMRT (p = 0·00 « 0·05). VMAT has the biggest TCP (80·76%) than the other three radiotherapy plans. With regard to normal tissue complications, probabilities were shown to be very low, of the order of 10-14 and 10-41 for bowel bag and femoral heads respectively. Conclusions: It can be concluded that 3DCRT plan improves conformity and decreases radiation sparing in the organ at risks, but the VMAT plan exhibits better homogeneity and greater TCP. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Radiotherapy in Practice Cambridge University Press

Dosimetric and radiobiological evaluation of four radiation techniques in preoperative rectal cancer radiotherapy

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References (27)

Publisher
Cambridge University Press
Copyright
© The Author(s), 2020. Published by Cambridge University Press
ISSN
1467-1131
eISSN
1460-3969
DOI
10.1017/S1460396920000564
Publisher site
See Article on Publisher Site

Abstract

Abstract Purpose: To compare tumour dose distribution, conformality, homogeneity, normal tissue avoidance, tumour control probability (TCP) and normal tissue complication probability (NTCP) using 3D conformal radiation therapy (3DCRT), 3- and 4-field intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with locally advanced rectal cancer. Materials and methods: Twenty-four patients staged T 1–3 N + M 0 with locally advanced rectal cancer underwent neoadjuvant chemoradiation therapy. Four different radiotherapy plans were prepared for each patient: 3DCRT, 3- and 4-field IMRT and VMAT are evaluated for target distribution using CI and homogeneity index (HI), normal tissue avoidance using D max, V 45, V 40, V 50 and TCP and NTCP using the Lyman–Kutcher–Burman model. Results: VMAT has better HI (HI = 1·32) and 3DCRT exhibited better conformality (CI = 1·05) than the other radiotherapy techniques. With regard to normal tissue avoidance, all radiotherapy plans met the constraints. D max in the 3DCRT plans was statistically significant (p = 0·04) for bladder and no significant differences in V 40 and V 50. In the bowel bag, no significant differences in D max for any radiotherapy plan and V 40 was lower in 3DCRT than VMAT (p = 0·024). In the case of femoral heads, 3DCRT has a statistically significant lower dose on D max than 4-field IMRT (p = 0·00 « 0·05). VMAT has the biggest TCP (80·76%) than the other three radiotherapy plans. With regard to normal tissue complications, probabilities were shown to be very low, of the order of 10-14 and 10-41 for bowel bag and femoral heads respectively. Conclusions: It can be concluded that 3DCRT plan improves conformity and decreases radiation sparing in the organ at risks, but the VMAT plan exhibits better homogeneity and greater TCP.

Journal

Journal of Radiotherapy in Practice – Cambridge University Press

Published: Dec 1, 2021

Keywords: dosimetric parameters; normal tissue complication probability; preoperative radiation therapy; rectal cancer; tumour control probability

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