Prospective evaluation of the setup errors and its impact on safety margin for cervical cancer pelvic conformal radiotherapy.
Pelvic conformal radiotherapy
Set-up errors
Set-up margin
Journal
Reports of practical oncology and radiotherapy : journal of Greatpoland Cancer Center in Poznan and Polish Society of Radiation Oncology
ISSN: 1507-1367
Titre abrégé: Rep Pract Oncol Radiother
Pays: Poland
ID NLM: 100885761
Informations de publication
Date de publication:
Historique:
received:
02
04
2019
revised:
22
10
2019
accepted:
19
02
2020
entrez:
7
3
2020
pubmed:
7
3
2020
medline:
7
3
2020
Statut:
ppublish
Résumé
The primary objective was to assess set-up errors (SE) and secondary objective was to determine optimal safety margin (SM). To evaluate the SE and its impact on the SM utilizing electronic portal imaging (EPI) for pelvic conformal radiotherapy. 20 cervical cancer patients were enrolled in this prospective study. Supine position with ankle and knee rest was used during CT simulation. The contouring was done using consensus guideline for intact uterus. 50 Gy in 25 fractions were delivered at the isocenter with ≥95% PTV coverage. Two orthogonal (Anterior and Lateral) digitally reconstructed radiograph (DRR) was constructed as a reference image. The pair of orthogonal [Anterior-Posterior and Right Lateral] single exposure EPIs during radiation was taken. The reference DRR and EPIs were compared for shifts, and SE was calculated in the X-axis, Y-axis, and Z-axis directions. 320 images (40 DRRs and 280 EPIs) were assessed. The systematic error in the Z-axis (AP EPI), X-axis (AP EPI), and Y-axis (Lat EPI) ranged from -12.0 to 11.8 mm, -10.3 to 7.5 mm, and -8.50 to 9.70 mm, while the random error ranged from 1.60 to 6.15 mm, 0.59 to 4.93 mm, and 1.02 to -4.35 mm. The SM computed were 7.07, 6.36, and 7.79 mm in the Y-axis, X-axis, and Z-axis by Van Herk's equation, and 6.0, 5.51, and 6.74 mm by Stroom's equation. The computed SE helps defining SM, and it may differ between institutions. In our study, the calculated SM was approximately 8 mm in the Z-axis, 7 mm in X and Y axis for pelvic conformal radiotherapy.
Sections du résumé
AIM
OBJECTIVE
The primary objective was to assess set-up errors (SE) and secondary objective was to determine optimal safety margin (SM).
BACKGROUND
BACKGROUND
To evaluate the SE and its impact on the SM utilizing electronic portal imaging (EPI) for pelvic conformal radiotherapy.
MATERIAL AND METHODS
METHODS
20 cervical cancer patients were enrolled in this prospective study. Supine position with ankle and knee rest was used during CT simulation. The contouring was done using consensus guideline for intact uterus. 50 Gy in 25 fractions were delivered at the isocenter with ≥95% PTV coverage. Two orthogonal (Anterior and Lateral) digitally reconstructed radiograph (DRR) was constructed as a reference image. The pair of orthogonal [Anterior-Posterior and Right Lateral] single exposure EPIs during radiation was taken. The reference DRR and EPIs were compared for shifts, and SE was calculated in the X-axis, Y-axis, and Z-axis directions.
RESULTS
RESULTS
320 images (40 DRRs and 280 EPIs) were assessed. The systematic error in the Z-axis (AP EPI), X-axis (AP EPI), and Y-axis (Lat EPI) ranged from -12.0 to 11.8 mm, -10.3 to 7.5 mm, and -8.50 to 9.70 mm, while the random error ranged from 1.60 to 6.15 mm, 0.59 to 4.93 mm, and 1.02 to -4.35 mm. The SM computed were 7.07, 6.36, and 7.79 mm in the Y-axis, X-axis, and Z-axis by Van Herk's equation, and 6.0, 5.51, and 6.74 mm by Stroom's equation.
CONCLUSION
CONCLUSIONS
The computed SE helps defining SM, and it may differ between institutions. In our study, the calculated SM was approximately 8 mm in the Z-axis, 7 mm in X and Y axis for pelvic conformal radiotherapy.
Identifiants
pubmed: 32140083
doi: 10.1016/j.rpor.2020.02.006
pii: S1507-1367(20)30020-1
pmc: PMC7049598
doi:
Types de publication
Journal Article
Langues
eng
Pagination
260-265Informations de copyright
© 2020 Greater Poland Cancer Centre. Published by Elsevier B.V. All rights reserved.
Références
Int J Radiat Oncol Biol Phys. 1995 Dec 1;33(5):1311-20
pubmed: 7493856
Int J Radiat Oncol Biol Phys. 1996 Jan 1;34(1):213-9
pubmed: 12118554
Med Dosim. 2005 Spring;30(1):36-42
pubmed: 15749010
Radiother Oncol. 2001 Feb;58(2):105-20
pubmed: 11166861
Jpn J Clin Oncol. 2011 Sep;41(9):1119-26
pubmed: 21875938
Radiother Oncol. 2001 Apr;59(1):87-93
pubmed: 11295211
Med Phys. 1996 Nov;23(11):1897-902
pubmed: 8947904
Int J Radiat Oncol Biol Phys. 2003 Jul 15;56(4):1105-11
pubmed: 12829148
Radiother Oncol. 1995 Jun;35(3):232-9
pubmed: 7480827
Radiother Oncol. 1997 Sep;44(3):265-70
pubmed: 9380826
Br J Radiol. 2009 Jan;82(973):49-61
pubmed: 18955413
Int J Radiat Oncol Biol Phys. 1995 Apr 30;32(1):227-33
pubmed: 7721620
Int J Radiat Oncol Biol Phys. 2000 Jan 15;46(2):499-506
pubmed: 10661359
Radiother Oncol. 2002 Jul;64(1):75-83
pubmed: 12208578
Med Phys. 2009 Mar;36(3):961-73
pubmed: 19378757
Int J Radiat Oncol Biol Phys. 1996 May 1;35(2):321-32
pubmed: 8635940
Radiat Oncol. 2011 Aug 24;6:101
pubmed: 21864393
Radiother Oncol. 1992 Aug;24(4):261-71
pubmed: 1410582
Radiother Oncol. 1999 Jul;52(1):29-34
pubmed: 10577683
Int J Radiat Oncol Biol Phys. 2000 Jul 1;47(4):1121-35
pubmed: 10863086
Strahlenther Onkol. 2012 May;188(5):395-401
pubmed: 22318329
Radiother Oncol. 2003 Jul;68(1):41-9
pubmed: 12885451