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Development of the 4D Phantom Using the 3D Gel Dosimetry for Liver SBRT: A Preliminary Study

S Noh1*, M Lee2 , K Yoon3 , J Kwak4 , B Cho5 , S Kim6 , H Kim7 , C Jeong8 , (1) ,,,(2) Asan Medical Center, Seoul, SEOUL, (3) Asan Medical Center, Seoul, SEOUL, (4) Asan Medical Center, Seoul, ,(5) Asan Medical Center, Seoul, ,(6) Asan Medical Center, Seoul, SEOUL, (7) Asan Medical Center, Seoul, Seoul, (8) Asan Medical Center, Seoul, Seoul


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: To verify the delivering precise dose at heterogeneous tissue in case of SBRT by patient specific 3D printed phantom and 3D gel dosimetry, which is the most advanced method being able to validate 3D dose distribution directly.

Methods: We made the 3D phantom using a 3D printer that takes account of the real patient’s organ based on CT images. And to mimic the patient respiration pattern, we applied to tumor motion depending on patient’s respiration data acquired from 4DCT using a Quasar respiratory motion system. We randomly selected a patient whose tumor is located in the liver dome because of inhomogeneous tissue. We made the BANG gel and in order to evaluate the linearity to dose of making gel, we irradiated the bilateral beam under the several MUs in the vials and the 3D printed bottles. And then we read the MR imaging and Get the R2 map. 3D gel consists of the patient's tumor shape and is set up to insert in Quasar motion system. After the installation at TureBeam, liver phantom is positioned at the top phase while taking 2D images and 3D-3D matching and 2D-2D matching using a CBCT. Beam delivery planning is the same as the real patient’s treatment plan.

Results: The result of relationship between absorbed dose and R2 value were 0.99 in the vial and Gamma analysis was performed in patient QA, but the insufficient result was somewhat meaningful.

Conclusion: In this study, we performed liver SBRT that reflects the patient’s respiratory using 3D printed phantom and 3D gel dosimetry for patient-specific QA. After going through some additional experiments, if we are a better cut off of oxygen from PLA, we expect that better results can be obtained by further improving the linearity between the dose of Gel and R2 value.


Gel Dosimeter, Respiration, Stereotactic Radiosurgery


Not Applicable / None Entered.

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