Position accuracy evaluation of multileaf collimator (MLC) static in linear accelerator

• Published in: IOP conference series. Materials Science and Engineering 2018-11, Vol.432 (1), p.12052
• Main Authors: Rahmat, Y, Pawiro, S A, Baihaqi, Y A, Fadli, M, Nainggolan, A
• Format: Article
• Language: English
• Subjects: Accuracy; Algorithms; Collimators; Dosimeters; Edge detection; Error analysis; Evaluation; Matlab; Position measurement
• ISSN: 1757-8981; 1757-899X; 1757-899X
• DOI: 10.1088/1757-899X/432/1/012052

This study was aimed to evaluate the accuracy of static MLC positions using gafchromic BT3 film. EBT3 gafchromic film was scanned using Vidar dosimetry Pro Advantage and was analyzed using Matlab algorithm. Matlab algorithm which determined leaf edge of MLC was using Edge Detection Function with Laplacian of Gaussian Method. The precision of MLC leafs on Linac 1 and Linac 2 was measured using the Matlab application code and being compared to early data in TPS setting. The measurement showed that average value of the best precision was obtained at line 6 and the lowest at line 2 both in Linac 1 and 2. MLC leaf measurement error using Matlab was still within tolerance limit AAPM TG 142 which is ± 1 mm. An Error value of the MLC was increased if the leaf movement over the normal position. This effect was caused by an influence of vertical line scattering (VL) and inaccuracy positioning of gafchromic film EBT3 when scanned. The result of this study showed that MLC position accuracy in LINA C 1 and 2 was still within tolerance limit based on AAPM PG 142. It could be an alternative measurement of MLC position accuracy more easily.