Sahachjesdakul, P. “A Comparison between the Las Vegas and the PTW EPID QC PHANTOM® for portal imaging quality assurance”. Journal of Thai Association of Radiation Oncology, vol. 17, no. 1, June 2011, pp. 86-91, https://he01.tci-thaijo.org/index.php/jtaro/article/view/203491.