Page 61 - Fisica In Medicina n° 1/2017

^Äëíê~Åí=cáëáÅá= =INCORRECT DLS VALUE. PRE TREATMENT VERIFICATION QA OF PLANS WERE PERFORMED USING BI-PLANAR DIODE DEVICES. A GAMMA ANALYSIS WAS CARRIED OUT USING DIFFERENT LOCAL/GLOBAL GAMMA CRITERIA: 3%/3 MM, 3%/2 MM, AND 2%/2 MM.ResultsOur results showed a good performance of Delta 4 and Delta4+ to detect DLS value furthermore in a very short time compared with the direct measures by other detectors (e.g. ionization chambers, films). Moreover preliminary data reported an increased detectability of possible discrepancies using different DLS values with a lower gamma criteria.Finally, the impact of two different values of DLS on PTV and OARs DVH points was evaluated, for IMRT and SMARTARC fields. The SMARTARC technique makes up for any DLS error as compared with the IMRT technique.ConclusionVariation of DLS parameter over time could be detected efficiently using bi-planar diode array. The Machine QA tool was useful for the aim. The quantification of a possible lack of constancy of DLS value and its clinical impact on the delivery could be useful to highlight the attention on the QA MLC program.52