TEST REPORT BEAMSCAN WITH HALCYON UZ Leuven, November 20 th, 2017 + = Ideal BEAMSCAN tank dimensions to fit perfectly into the Halcyon bore Fast tank positioning using the Halcyon lasers, no electronics on the couch Automatic and fast filling with the function Match water level to sensor Auto-correction of couch tilt using the function Leveling in less than 2 minutes No manual adjustment due to BEAMSCAN s unique AutoSetup features Easy and fast setup in less than 20 minutes Convincing and fast measurement results due to continuous scanning
BEAMSCAN measurements at Halcyon (UZ Leuven, Belgium) A few weeks after the installation of the first Halcyon in Europe PTW got the possibility to perform measurements with BEAMSCAN and in order to demonstrate how easy the use is with the automatic setup procedures of BEAMSCAN. The goal was to elaborate an optimal workflow for all BEAMSCAN users with Halcyon. Preparation: For the use of BEAMSCAN together with Halcyon only a longer water hose (1.6 m) is needed. Workflow: 1. Position the BEAMSCAN beside the patient couch (handle towards Halcyon). Connect the power cable and LAN cable to the PC (or use wifi access point) and switch on BEAMSCAN. 2. Put the Varian service plate onto the couch to protect the couch against scratches (with one side approx. 29 cm from the upper end of the couch). Lift the couch to a height of approx. 75 cm above the floor. - 2 -
3. Move the BEAMSCAN lift to the same height as the couch. 4. Shift the BEAMSCAN PMMA-tank to the couch and turn the PMMA-tank clockwise 180. It should be placed 40 cm from the end of the couch and with the crosshair at the bottom in the middle of the couch. Switch control pendant (ipod) on and perform a reference run. Now fix the field chamber using TRUFIX holder. - 3 -
5. Move the couch slowly into the bore and shift the PMMA-tank on the couch so that the crosshair at the bottom is aligned with the Halcyon cross laser from the top. Then move the couch up/downwards until the laser from the side is visible in the middle of the side markings of the BEAMSCAN tank (red arrow). 6. Then move the couch with BEAMSCAN into the measuring position (isocenter) and position the reference chamber using the small cross at the top of the bore. - 4 -
7. Use the BEAMSCAN control pendant (ipod) to move the detector in B to position 100 mm and set a new zero point. Then perform the function match water level to sensor. Now the water is pumped automatically into the tank to the desired filling height within 4 minutes. 8. The total weight of the (not completely) filled water phantom (approx. 192 kg) leads to an elastic deflection of the couch of a few millimeters. Use the control pendant and perform the function Leveling. 9. Use the MV imager to check that the water surface is exactly at SSD 90 cm. Move the MV imager to 84.3, open the upper jaw to 5 cm and the lower jaw to 14 cm so you get an orthogonal beam parallel to the water surface. Use the Halcyon measuring tool to measure the distance between isocenter (yellow cross) and water surface. This should be 100 mm. Correct a deviation by changing the couch height. - 5 -
10. For your information, you can use the MV imager to check the position of the detector. Using a brass build-up cap increases the visibility of the chamber. It is not necessary to correct a deviation from the beam center manually. This will be done automatically using the BEAMSCAN AutoSetup function BeamCenter Adjustment. 11. Start BEAMSCAN software, switch Halcyon beam on and perform the functions BeamCenterAdjustment and AutoFieldAlignment with 10 x 10 cm field size. Hint: Due to the elastic deflection of the couch an inclination angle of approx. 0.3 in C is expected. The Leveling function has this measured and a coordinate transformation has been performed. An inclination angle of 0.3 corresponds to an incline of the 500 mm total scanning range of approx. 2.5 mm. - 6 -
12. AutoSetup is closed and a task list for Halcyon measurements is loaded. 13. With the task list PDD s and in-plane and cross-plane profiles for the field sizes 2 x 2 cm, 4 x 4 cm, 6 x 6 cm, 8 x 8 cm, 10 x 10 cm, 20 x 20 cm and 28 x 28 cm in the depths 13 mm, 50 mm, 100 mm and 200 mm have been measured within about 30 minutes. - 7 -
14. We analyzed for example the PDD for the field size 10 x 10 cm. An analysis according to IAEA 398 showed R100 at 13.02 mm depth. 15. We analyzed also the in-plane profile at 100 mm depth (isocenter). The analyze is automatically performed according to Fogliata resulting in a CAX deviation of -0.14 mm, a field size of 9.957cm and a penumbra of 6.21 mm left and 5.95 mm right. - 8 -
Conclusion: Following this workflow allows a quick and easy setup of BEAMSCAN at Halcyon in about 20 minutes. The white marks and lines on the BEAMSCAN tank allow an easy adjustment using the Halcyon lasers. The BEAMSCAN tank fits perfectly into the 1 m bore of the Halcyon allowing the use of the whole scanning range of BEAMSCAN in in-plane and cross-plane direction. The big advantages of BEAMSCAN are the AutoSetup functions like Match water level to sensor which allows an automatic filling to the desired filling height, Leveling which performs the auto-correction of the couch tilt in less than 2 minutes. PDD s have been measured with 5 mm/s scanning speed, profiles with 10 mm/s scanning speed and all curves show very smooth raw data. The results of these test measurements are very good. Handling of the BEAMSCAN PMMA-tank (shift onto the couch) could probably be improved with an additional transfer plate with handles. Also, the contrast of the Semiflex 3D at the MV imager could be improved when using a brass build-up cap or a special marker-cap for the chamber. Thanks to its unique patented automatic functions BEAMSCAN constitutes a perfect solution for measurements at the Halcyon machine. We would like to express our special thanks to the Leuven Halcyon team for their sincere guidance, helpful information, and all friendly support they provided us during our tests. - 9 -