Clinically evaluating directional dependence of 2D seven29 ion-chamber array with different IMRT plans

Syam Kumar, Aswathi Cheruparambil, Anjana Parakkat Thokkayil, Sitha Gangadharan Padmini, Aparna Perumangat


Purpose: This study aims to clinically evaluate the directional dependence of a 2D seven29 ion-chamber array with different intensity-modulated radiotherapy (IMRT) plans.

Methods: Twenty-five patients who had already been treated with IMRT plans were selected for the study. Verification plans were created in an Eclipse treatment planning system (TPS) for each treatment plan. The verification plans were executed twice for each patient. The first IMRT plan used a true gantry angle (plan-related approach), and the second plan used a 0° gantry angle (field-related approach). Measurements were performed using a Varian Clinac 2100 iX linear accelerator. The fluence was measured for all the delivered plans and analyzed using Verisoft software. A comparison of the fluence was performed between IMRT with a static gantry (0° gantry angle) and real gantry angles.

Results: The results indicate that the Gamma average was 98.8 % for IMRT with a 0° gantry angle and 96.616% for IMRT with a true gantry angle. Average percent difference of normalized doses for IMRT delivered with zero degree gantry angle and IMRT with actual gantry angles is 0.15 and 0.88 respectively.

Conclusion: The ion chamber of the 2D array used in IMRT verification has angular dependence, reducing the verification accuracy when the 2D array is used for measuring the actual beams of the treatment plan.


IMRT; 2D Array; Octavius Phantom; Gamma Analysis

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Bohsung J, Charité Berlin KFS, Mitte S. The 2d-array seven 29a new way of dosimetric verification of IMRT beams. PTW-Freiburg Lörracher Straße 7, Freiburg, Germany, 2004.

Sadagopan R, Bencomo JA, Martin RL, et al. Characterization and clinical evaluation of a novel IMRT quality assurance system. J Appl Clin Med Phys. 2009;10:2928.

Van Esch A, Clermont C, Devillers M, et al. On-line quality assurance of rotational radiotherapy treatment delivery by means of a 2D ion chamber array and the Octavius phantom. Med Phys. 2007;34:3825-37.

Sotiri Stathakis. Ionization chamber array for patient specific VMAT, Tomotherapy and IMRT QA. J Phys: Conf Ser. 2010;250.

Daniel J, Kishore M, Das S, et al. Gantry‐angle dependence of a 2D ion chamber array for IMAT QA. Med Phys.2010; 37:3237.

Li QL, Deng XW, Chen LX, et al. The angular dependence of a 2-dimensional diode array and the feasibility of its application in verifying the composite dose distribution of intensity-modulated radiation therapy. Chin J Cancer. 2010;29:617-20.

Hussein M, Adams EJ, Jordan TJ, et al. A critical evaluation of the PTW 2D-ARRAY seven29 and OCTAVIUS II phantom for IMRT and VMAT verification. J Appl Clin Med Phys. 2013;14:4460.

Li JG, Yan G, Liu C. Comparison of two commercial detector arrays for IMRT quality assurance. J Appl Clin Med Phys. 2009; 10:2942.

Low DA. Gamma Dose Distribution Evaluation Tool. J Phys.: Conf Ser. 2010:250 012071.

Spezi E, Angelini AL, Romani F, Ferri A. Characterization of a 2D ion chamber array for the verification of radiotherapy treatments. Phys Med Biol. 2005;50:3361-73.

Syamkumar SA, Padmanabhan S, Sukumar P, et al. Characterization of response of 2d array seven29 detector and its combined use with Octavius phantom for the patient-specific quality assurance in rapidarc treatment delivery. Med Dosim. 2012; 37:53-60.

Choi D, Nookala P, Patyal B. How to improve the dose accuracy for gantry angle dependent patient specific IMRT QA using 2D Ion chamber array with octavius phantom. Med Phys. 2012; 39:3725.

Jin H, Keeling V, Ahmad S. Effect of energy and field size on angular dependence of 2d diode array. Med Phys. 2013;40:220.

Shimohigashi Y, Araki F, Tominaga H, et al. Angular dependence correction of MatriXX and its application to composite dose verification. J Appl Clin Med Phys. 2012;13:3856.

Alber M, Broggi S, Wagter CD, et al. Guidelines for the Verification of IMRT. ESTRO No. 9, Mijnheer, Georg, 2008.

Prescribing, Recording, and Reporting photon- Beam Intensity-Modulated Radiation Therapy (IMRT): Contents. J ICRU. 2010;10(1):NP.


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