DOI: http://dx.doi.org/10.18203/2320-6012.ijrms20192914

Retrospective analysis of random and systematic errors in radiation therapy of head and neck cancer patients and its clinical predictive implications with VMAT treatment

Jui Deb, Santanu Chaudhuri, Debashis Panda, Sujit Nath Sinha, Sasi Kumar, Navin Kumar, Saumen Basu, Neeraj Kumar, Aneesh P. M., Sanjeev K. Gupta

Abstract


Background: The accuracy of radiotherapy is based on the matching of 2D portal/CBCT image with a reference image. The aim of this study is to determine the random and systematic setup errors (in cm) in radiotherapy of head and neck cancer patients and to derive the setup margin and its clinical implications.

Methods: Author retrospectively reviewed the records of 25 head and neck cancer (HNC) patients treated with radiotherapy between Dec 2017 and July 2018. After immobilization, setup accuracy was assessed by registration of XVI image with planning reference image using Elekta XVI image guidance system and the isocenter correction was applied. For each patient 10 CBCT image sets were taken. The translational errors in X, Y and Z directions were used to estimate systematic (Σ) and random (σ) errors and to derive the final setup margin by using van Herk’s formula (2.5Σ + 0.7σ).

Results: The mean translational errors ranges from -0.23 cm to 0.32 cm in Lateral (X), -0.15 to 0.16 cm in Longitudinal (Y) and -0.11 to 0.17 cm in vertical (Z) directions. The Mean and SD for systematic errors 0.21±0.13, 0.11±0.18, 0.14±0.11 and random error (in cm) are -0.03±0.33, 0.00±0.21 and 0.05±0.30 in X, Y and Z axis respectively. The final total margin for CTV to PTV including setup margin in the X, Y and Z directions (in cm) were 0.56, 0.61, and 0.47 respectively.

Conclusion: Thus, the precise immobilization techniques are very important to reduce the setup margins, and the number of CBCTs during head and neck radiotherapy treatment.


Keywords


CBCT image, Head and neck cancer, Immobilization, Random and systematic errors, Radiation therapy, Setup margins

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References


Hadi SM, Farshid A, Mastaneh S, Elham H, Mina T, Rostami A, et al. Evaluation of patient setup accuracy and determination of optimal setup margin for external beam radiation therapy using electronic portal imaging device. Canc Therapy Oncol Int J. 2018;11(2):001-08.

Jones D. ICRU Report 50-prescribing, recording and reporting photon beam therapy. Med Physics. 1994;21(6):833-34.

Landberg T, Chavaudra J, Dobbs J, Gerard JP, Hanks G, Horiot JC. Report 62. J Int Comm Radiation Units Measurements. 1999;32(1):48-51.

Morgan-Fletcher LS. Prescribing, recording and reporting photon beam therapy (supplement to ICRU report 50), ICRU report 62. ICRU, pp. ix+52, 1999 (ICRU Bethesda, MD). Brit J Radiol. 2001;74(879):294.

Bel A, Herk M, Lebesque JV. Target margins for random geometrical treatment uncertainties in conformal radiotherapy. Med Phys. 1996;23:1537-47.

Stroom JC, Boer HC, Huizenga H, Visser AG. Inclusion of geometrical uncertainties in radiotherapy treatment planning by means of coverage probability. Int J Radiat Oncol Biol Phys. 1999;43(4):905-19.

Hong TS, Tome WA, Chappell RJ, Chinnaiyan P, Mehta MP, Harari PM. The impact of daily setup variation on head-and-neck intensity-modulated radiation therapy. Int J Radiat Oncol Biol Phys. 2005;61(3):779-88.

Stroom JC, Heijmen BJ. Geometrical uncertainties, radiotherapy planning margins, and the ICRU-62 report. Radio Ther Oncol. 2002;64(1):75-83.

Herk VM, Remeijer P, Lebesque JV. The probability of correct target dosages: Dose -population histograms for deriving treatment margins for radiotherapy. Int J Radiat Oncol Biol Phys. 2000;47(4):1121-35.

Herk VM. Errors and margins in radiotherapy. Semin Radiat Oncol. 2004;14:52-64.

Hurkmans CW, Remeijer P, Lebesque JV, Mijnheer BJ. Set up verification using portal imaging; review of current clinical practice. Radiother Oncol. 2001;58:105-20.

Kataria T, Abhishek A, Chadha P, Nandigam J. Set-up uncertainties: Online correction with X-ray volume imaging. J Cancer Res Ther. 2011;7(1):40-6.

Gupta T, Chopra S, Kadam A, Agarwal JP, Devi PR, Laskar GS. Assessment of three-dimensional set-up errors in conventional head and neck radiotherapy using electronic portal imaging device. Radiat Oncol. 2007;2:44.

Xu F, Wang J, Bai S, Xu QF, Shen YL, Zhong RM. Interfractional and intrafractional setup errors in radiotherapy for tumours analysed by cone beam computed tomography. Chin J Cancer. 2008;27(10):1111-6.