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ESTRO 2020

Session Item

Physics track: Dose measurement and dose calculation
9319
Poster
Physics
00:00 - 00:00
Dosimetric analysis of the effects of a temporary tissue expander on the radiotherapy technique
So Hyun PARK, Korea Republic of
PO-1395

Abstract

Dosimetric analysis of the effects of a temporary tissue expander on the radiotherapy technique
Authors: Jinhyun Choi.(Jeju National University Hospital, Department of Radiation Oncology, Jeju, Korea Republic of), Young Suk Kim.(Jeju National University Hospital, Department of Radiation Oncology, Jeju, Korea Republic of), So Hyun PARK.(Jeju National University Hospital, Department of Radiation Oncology, Jeju, Korea Republic of)
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Purpose or Objective

Temporary tissue expander (TTE) has metal port with high density. The aim of this study was to evaluate the dose effect of TTE according to the radiotherapy techniques for breast cancer patients.

Material and Methods

The CT images of 3D printed breast phantom with a TTE were acquired for dosimetric analysis. For dose measurement during 180 cGy of radiotherapy, 13 to 15 EBT3 films were attached to the TTE including metal port area. The treatment planning generated three-dimensional conformal radiotherapy (3DCRT), field in field, intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) was applied to whether the bolus was used and whether the artifact was corrected. Difference at each point between measured dose and calculated dose was analyzed to determine their association with radiotherapy techniques.

Results

The effect of metal port on radiation dose was related to the treatment technique (p = 0.018); dose difference between measured and calculated occurred in 6.8% (191.6 cGy vs. 179.5 cGy) of 3DCRT with bolus and artifact correction followed by 5.8% (190.2 cGy vs. 179.8 cGy) of VMAT with artifact correction. IMRT with the bolus showed a minimum difference of 0.3% (180.7 cGy vs. 181.3 cGy). There were no significant dose differences at the points except skin surface and metal port location.

Conclusion

The metal port within TTE resulted in increased dose difference to breast during radiotherapy, but absolute dose difference was minimal. Future analyses need assess whether this dose difference could affect clinical outcomes.