ESTRO 2023 - Abstract Book

S469

Sunday 14 May 2023

ESTRO 2023

(NID) designed to measure the AIF, removing the need for arterial blood sampling. This work presents the design and fabrication of the NID. Materials and Methods The sensitive volume of the detector consists of 64 plastic scintillating fibers, 10 cm in length, arranged in 2 layers of 32 fibers. Serial polishing of one fiber-end was performed for each fiber to prepare them to be coupled to 16 cm long optical transmission fibers. The coupling was performed by placing the two fiber-ends in a transparent heat shrink tube filled with a UV curing optical epoxy. A 3D printed plastic shell with 20% infill was used to hold the fibers in the desired shape and block ambient light. The shell was also used to hold the bare end of the optical fibers in an 8x8 grid to allow them to be coupled to an 8x8 silicon photomultiplier (SiPM) array. An index matching silica sheet was placed between the SiPM array and the optical fibers. Velcro straps are used to hold a patient’s arm in place. Black acrylic sheets are used to block ambient light from reaching the scintillating fibers. The SiPM is connected to an electronic board to read-out the signal captured by the scintillating fibers. To test the NID functionality, an un-calibrated 18F solution was placed in the detector volume for a ten-minute acquisition. F-18 half-life was calculated and compared to literature values. Results Figure 1 illustrates the finished NID and accessories. The ergonomic design of the NID allows the patient to rest their arm on the detector surface without straining. This is important for longer dPET scan times to avoid patient movement. Figure 2 shows the measured decay of F-18 in the NID. The calculated half-life is within 4.5% of literature values. The same scan shows that 9 out of the 64 channels are non-functional.

Conclusion The constructed NID is functional and capable of measuring radiation from an F-18 source. These tests were done with F- 18, but the NID would work with any PET radioisotope. The fiber-coupling procedure works, but further quality control steps are needed to remove non-functional channels. Additional measurements with clinical phantoms and patients are planned to characterise the NID.

PD-0587 End-to-end validation of stereotactic radiosurgery delivery for multiple targets E. Gershkevitsh 1 , B. Petrovic 2 , V. Mahalwar 3 , R. Slade-Carter 4 , A. Blackmore 5 , A. Saplaouras 6

1 North Estonia Medical Center, Radiotherapy, Tallinn, Estonia; 2 Institute of Oncology Vojvodina, Radiotherapy, Novi Sad, Serbia; 3 GenesisCare UK, Radiotherapy, London, United Kingdom; 4 GenesisCare UK, Radiotherapy, Oxford, United Kingdom; 5 GenesisCare UK, Radiotherapy, Southampton, United Kingdom; 6 GenesisCare UK, Radiotherapy, Bristol, United Kingdom

Purpose or Objective