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A Tissue Equivalent Bolus for Dose Optimization in Radiotherapy

z xu1*, W Lu1 , J Qiu1 , L Jing2 , W Jiang3 ,h yu1 , K Hou1 ,L Shi1 , (1) Taishan Medical University, Taian, Shandong, (2) Taian tumor hospital, Taian, ,(3) Yantai Yuhuangding Hospital, Qingdao University School of Medicine


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: We fabricated a customized tissue equivalent bolus to optimize radiation dose and evaluated its application in radiotherapy for superficial cancers.

Methods: The fabrication of the customized bolus is based on the 3D printing technology and a kind of tissue equivalent hydrogel. We scanned a Shimadzu anthropomorphic phantom using a diagnostic computed tomography (CT). An oncologist contoured a lesion of the nose and generated a bolus to optimize the dose on the CT images using the treatment planning system (TPS). The CT images with contoured bolus were then imported to the mimics software to generate a shell of bolus in STL format. We filled the tissue equivalent hydrogel in the 3D printed shell, and removed the shell after bolus was solidified. Finally, the CT values of the bolus were compared with the CT values of the phantom. Change in the dose volume histogram (DVH) of the lesion after adding the bolus was observed.

Results: We can see it clearly that the designed tissue equivalent bolus was completely suitable for the phantom's surface skin, and there is no visible air gap between them. The CT value of phantom’s nose was 12 Hounsfield Unit (HU), while the CT value of tissue equivalent bolus was 8HU. The DVH image showed that the dose was improved,and the absorbed dose of radiotherapy can be optimized at the lesion site.

Conclusion: This study fabricated a customized 3D bolus using a tissue equivalent hydrogel. The bolus is completely suitable for the patient's surface skin. The CT values of the bolus can be adjusted as needed, thus it can suit different sites of patients in the clinic. This may benefit the clinical treatment planning optimization for superficial cancers.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by National Key Research and Development Program of China (2016YFC0103400), Key Research and Development Program of Shandong Province (2017GSF218075), Jianfeng Q. was supported by the Taishan Scholars Program of Shandong Province (TS201712065).


3D, Modeling, Radiation Dosimetry


TH- Brachytherapy: Dose optimization and planning

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