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The ratio of weight loss to planning target volume significantly impacts setup errors in nasopharyngeal cancer patients undergoing helical tomotherapy with daily megavoltage computed tomography Cover

The ratio of weight loss to planning target volume significantly impacts setup errors in nasopharyngeal cancer patients undergoing helical tomotherapy with daily megavoltage computed tomography

Open Access
|Sep 2016

Figures & Tables

Setup error of the medial-lateral (ML) direction at each treatment fraction.
Setup error of the medial-lateral (ML) direction at each treatment fraction.
Setup error of the superior-inferior (SI) direction at each treatment fraction.
Setup error of the superior-inferior (SI) direction at each treatment fraction.
Setup error of the anterior-posterior (AP) direction at each treatment fraction.
Setup error of the anterior-posterior (AP) direction at each treatment fraction.
Linear regression graph of anterior-posterior (AP) setup error and weight loss normalized by planning target volume (PTV) (R2 = 0.059, p < 0.001).
Linear regression graph of anterior-posterior (AP) setup error and weight loss normalized by planning target volume (PTV) (R2 = 0.059, p < 0.001).

Setup errors by the specified threshold

ML error (%)SI error (%)AP error (%)
< 1.0 mm3549 (49.1)2471 (34.2)525 (7.3)
1.0~1.9 mm2315 (32.0)2076 (28.7)939 (13.0)
2.0~2.9 mm925 (12.8)1390 (19.2)1492 (20.6)
3.0~3.9 mm314 (4.3)729 (10.1)1800 (24.9)
4.0~4.9 mm85 (1.2)330 (4.6)1310 (18.1)
≥ 5.0 mm45 (0.6)237 (3.3)1167 (16.1)

Patient characteristics (n = 217)

VariableNumber (%)
Age
Median46
Range17–76
Sex
Male160(73.7)
Female57(26.3)
T stage
197(44.7)
232(14.7)
350(23.0)
438(17.5)
N stage
051(23.5)
167(30.9)
267(30.9)
3a18(8.3)
3b15(6.9)
AJCC stage
I29(13.4)
II47(21.7)
III76(35.0)
IVA32(14.7)
IVB33(15.2)
Chemotherapy
No27(12.4)
Yes190(87.6)
Fraction
33 (2.12 Gy/fraction)182(83.9)
35 (2 Gy/fraction)35(16.1)

Setup error by clinical factors

ML errorSI errorAP error
Overall1.2 ± 0.61.8 ± 0.83.4 ± 1.4
T stage
1,2 (n = 129)1.2 ± 0.61.8 ± 0.93.3 ± 1.5
3,4 (n = 88)1.1 ± 0.51.7 ± 0.83.5 ± 1.3
p value0.2410.8140.414
N stage
0, 1 (n = 117)1.1 ± 0.61.7 ± 0.83.4 ± 1.3
2, 3a, 3b (n = 100)1.2 ± 0.61.9 ± 0.93.4 ± 1.5
p value0.1330.2390.890
BMI
< 25 (n = 138)1.2 ± 0.61.7 ± 0.83.2 ± 1.3
≥ 25 (n = 79)1.2 ± 0.51.9 ± 0.93.6 ± 1.5
p value0.8450.1770.053
PTV
< 850 cc (n = 113)1.2 ± 0.71.9 ± 0.93.6 ± 1.5
≥ 850 cc (n = 104)1.2 ± 0.51.6 ± 0.73.2 ± 1.3
p value0.2920.0210.03
Weight loss
≤ 5% (n = 84)1.1 ± 0.41.6 ± 0.72.9 ± 1.1
> 5% (n = 133)1.2 ± 0.61.9 ± 0.93.6 ± 1.5
p value0.2790.010<0.001
DOI: https://doi.org/10.1515/raon-2016-0047 | Journal eISSN: 1581-3207 | Journal ISSN: 1318-2099
Language: English
Page range: 427 - 432
Submitted on: Mar 15, 2016
Accepted on: Jul 19, 2016
Published on: Sep 8, 2016
Published by: Association of Radiology and Oncology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 times per year

© 2016 Wei-Hsien Hou, Chun-Wei Wang, Chiao-Ling Tsai, Feng-Ming Hsu, Jason Chia-Hsien Cheng, published by Association of Radiology and Oncology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.