(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: : To report the process of commissioning Elekta High Dose Rate (HDR) Valencia Applicators for treatment of skin cancer, in conjunction with an Elekta Flexitron Ir-192 remote afterloader.
Methods: Elekta Valencia applicators are available in 2 and 3 cm diameters (H2 and H3 respectively). EBT film was placed on a solid water flat phantom with 3 mm buildup. A dose of 5 Gy to 3 mm depth was delivered using each of the applicators, to measure the 2D dose distribution on film, with the source at three different dwell positions - 1119 mm, 1120 mm, and 1121 mm. Flatness and symmetry of the dose distribution were evaluated using RIT software. The most symmetric and flat profiles corresponded to the 1120 mm dwell position, confirming it as the chosen dwell position for clinical use. The percentage depth dose (pdd) was measured with an IBA PPC05 plane parallel chamber as the ratio of the reading at any depths (mm) in solid water to the reading with a 3 mm reference depth for clinical use. Indirect output verification was achieved measuring a correspondence factor (CF), by taking the ratio of the reading with a Valencia applicator adapter for a Standard Imaging HDR 1000 Plus well chamber and the reading at chamber calibration reference conditions. The measured CF was then compared with reference values from the manufacturer, derived from published data (Granero et al., Med. Phys. 2008, 35:495)
Results: The pdd results showed the maximum deviation was 2.2% and -3.2% for H2 and H3respectively. The indirect output verification showed a maximum deviation of 0.43% and -1.05% for H2 and H3 respectively.
Conclusion: Elekta Valencia H2 and H3 applicator commissioning was carried out with excellent agreement to manufacturers’ specified dosimetric checkpoints and published reference data.
Keywords
Commissioning, HDR, Ir-192 Source
Taxonomy
Not Applicable / None Entered.
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