Analyzing the patient isocenter positional accuracy with portal imaging acquired at different gantry angles and its dosimetrical impact on the dose delivery for head and neck cancers

Abstract

Objective: This study aimed to analyze the effect of different gantry angles on portal imaging in terms of isocenter shifts and their dosimetric impact on dose delivery.

Methods: Thirty patients with head and neck cancers were prospectively selected for this study. The reference anterior to posterior (AP) digitally reconstructed reference radiograph image was obtained at a gantry angle of 0°. The AP portal images were acquired at angles of 0°, 0.5°, 1°, 1.5°, and 2.0°. The average deviation of the isocenter shift with respect to the zero-gantry angle was calculated. To check the dosimetric effects, the reference fluence was compared with different fluences measured at different isocenter shifts.

Results: The average isocenter shift differences in the lateral direction were 0.7 mm, 1.3 mm, 1.9 mm, and 2.5 mm. The average difference was <±0.1 mm for isocenter shift in the longitudinal direction. The results of the statistical analysis showed that the average isocenter shift and gamma pass rate with respect to the different isocenter position errors were significant in the lateral direction.

Conclusion: The results of this study showed that as the gantry angle increased, the isocenter shifted and the percentage of deviation in the lateral direction increased.

Keywords

electronic portal imaging devices / gantry angles / intensity-modulated radiotherapy / isocenter shift / portal imaging / positional accuracy

References

[1] HunteSO, ClarkCH, ZyuzikovN, Nisbet A. Volumetric modulated arc therapy (VMAT): a review of clinical outcomes—what is the clinical evidence for the most effective implementation? Br J Radiol. 2022;95(1136):20201289.

[2] RammU, Köhn J, RodriguezDominguez R, et al. Feasibility study of patient positioning verification in electron beam radiotherapy with an electronic portal imaging device (EPID). Phys Medica. 2014;30:215-220.

[3] HermanMG, BalterJM, JaffrayDA, et al. Clinical use of electronic portal imaging: Report of AAPM Radiation Therapy Committee Task Group 58. Med Phys. 2001;28:712-737.

[4] GuoW, Muller-Polyzou R, ChenZ, MeierN, Georgiadis A. Patient Positioning in Radiotherapy. IEEE Med Meas Appl MeMeA 2020 - Conf Proc. 2020:20-25.

[5] vanElmpt W, McDermott L, NijstenS, WendlingM, LambinP, MijnheerB. A literature review of electronic portal imaging for radiotherapy dosimetry. Radiother Oncol. 2008;88:289-309.

[6] LangmackKA. Portal imaging. Br J Radiol. 2001;74:789-804.

[7] SiebersJV, KeallPJ, WuQ, Williamson JF, Schmidt-UllrichRK. Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans. Int J Radiat Oncol Biol Phys. 2005;63:422-433.

[8] XingL, LinZX, DonaldsonSS, et al. Dosimetric effects of patient displacement and collimator and gantry angle misalignment on intensity modulated radiation therapy. Radiother Oncol. 2000;56:97-108.

[9] VanHerk M. Errors and Margins in Radiotherapy. Semin Radiat Oncol. 2004;14:52-64.

[10] PrabhakarR, Laviraj MA, HareshKP, JulkaPK, RathGK. Impact of patient setup error in the treatment of head and neck cancer with intensity modulated radiation therapy. Phys Medica. 2010;26:26-33.

[11] GovindarajK, Shanmugam S, SampathrajanS. A feasibility and pilot study of the clinical efficacy of a custom designed handgrip device to improve patient immobilisation for the external beam radiotherapy of oesophageal cancers. Radiat Eff Defects Solids. 2022;177:834-846.

[12] HoogemanMS, Van Herk M, De BoisJ, LebesqueJV. Strategies to reduce the systematic error due to tumor and rectum motion in radiotherapy of prostate cancer. Radiother Oncol. 2005;74:177-185.

[13] GrafR, WustP, BudachV, Boehmer D. Potentials of on-line repositioning based on implanted fiducial markers and electronic portal imaging in prostate cancer radiotherapy. Radiat Oncol. 2009;4:13.

[14] GramD, GramD, HaraldssonA, et al. Residual positioning errors and uncertainties for pediatric craniospinal irradiation and the impact of image guidance. Radiat Oncol. 2020;15:1-11.

[15] BelA, VosPH, RodrigusPT, et al. High-Precision Prostate Cancer Irradiation By Clinical Application of an Offline Patient Setup Verification Procedure, Using Portal Imaging. Int J Radiat Oncol Biol Phys. 1996;35:321-332.

[16] KangS, LiJ, MaJ, et al. Evaluation of interfraction setup variations for postmastectomy radiation therapy using EPID-based in vivo dosimetry. J Appl Clin Med Phys. 2019;20:43-52.

[17] ZhangX, DaiG, ZhongR, et al. Radiomics analysis of EPID measurements for patient positioning error detection in thyroid associated ophthalmopathy radiotherapy. Phys Medica. 2021;90:1-5.

[18] TanakaY, OitaM, InomataS, Fuse T, AkinoY, ShimomuraK. Impact of patient positioning uncertainty in noncoplanar intracranial stereotactic radiotherapy. J Appl Clin Med Phys. 2020;21:89-97.

[19] MiuraH, Hiokikazunari, OzawaS, et al. Uncertainty in the positioning of patients receiving treatment for brain metastases and wearing surgical mask underneath thermoplastic mask during COVID-19 crisis. J Appl Clin Med Phys. 2021;22:274-280.

[20] DaiG, ZhangX, LiuW, et al. Analysis of EPID Transmission Fluence Maps Using Machine Learning Models and CNN for Identifying Position Errors in the Treatment of GO Patients. Front Oncol. 2021;11:1-13.

[21] MoreM, JainV, GurjarOP. Clinical experience of intensity modulated radiotherapy pre-treatment quality assurance for carcinoma head and neck patients with epid and imatrixx in rural center. J Biomed Phys Eng. 2020;10:691-698.

[22] RowshanfarzadP, McGarry CK, BarnesMP, SabetM, EbertMA. An EPID-based method for comprehensive verification of gantry, EPID and the MLC carriage positional accuracy in Varian linacs during arc treatments. Radiat Oncol. 2014;9:1-10.

[23] GrégoireV, Ang K, BudachW, et al. Delineation of the neck node levels for head and neck tumors: a 2013 update. DAHANCA, EORTC, HKNPCSG, NCIC CTG, NCRI, RTOG, TROG consensus guidelines. Radiother Oncol. 2014;110(1):172-181.

[24] ChaikhA, GiraudJY, PerrinE, Bresciani JP, BalossoJ. The choice of statistical methods for comparisons of dosimetric data in radiotherapy. Radiat Oncol. 2014;9:1-11.

[25] VanderstraetenB, Reynaert N, PaelinckL, et al. Accuracy of patient dose calculation for lung IMRT: A comparison of Monte Carlo, convolution/superposition, and pencil beam computations. Med Phys. 2006;33:3149-3158.

[26] WoonW, Ravindran PB, EkanayakeP, VikramanS, LimYYF, KhalidJ. A study on the effect of detector resolution on gamma index passing rate for VMAT and IMRT QA. J Appl Clin Med Phys. 2018;19:230-248.

[27] SukumarP, Padmanaban S, JeevanandamP, SyamKumar SA, Nagarajan V. A study on dosimetric properties of electronic portal imaging device and its use as a quality assurance tool in Volumetric Modulated Arc Therapy. Reports Pract Oncol Radiother. 2011;16:248-255.

[28] PANDUB, KhannaD, MohandassP, et al. Dosimetric comparison and plan evaluation of different dose computing algorithms for different radiotherapy techniques in head and neck tumours. Iran J Med Phys. 2022;19:346-355.

RIGHTS & PERMISSIONS

2024 2024 The Author(s). Precision Radiation Oncology published by John Wiley & Sons Australia, Ltd on behalf of Shandong Cancer Hospital & Institute.