Dosimetric analysis of the effects of a temporary tissue expander on the radiotherapy technique
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MEDICAL PHYSICS
Dosimetric analysis of the effects of a temporary tissue expander on the radiotherapy technique So Hyun Park1 · Young Suk Kim1 · Jinhyun Choi1 Received: 23 March 2020 / Accepted: 21 September 2020 © Italian Society of Medical Radiology 2020
Abstract Aims The current study aimed to evaluate the dose effect of a temporary tissue expander (TTE) according to the radiotherapy technique for breast cancer patients. Materials and methods Computed tomography images of a 3D-printed breast phantom with a TTE were acquired for dosimetric analysis. For dose measurement during 180 cGy of radiotherapy, 13 EBT3 films were attached to the TTE while including the metal port area. Treatment planning was performed for three-dimensional conformal radiotherapy (3DCRT), field-in-field radiotherapy, intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) while considering whether a bolus was used and whether artifacts were corrected. The difference at each point between the measured mean and calculated doses was analyzed to determine the association with the radiotherapy techniques. Results The effect of the metal port on the radiation dose was associated with the treatment technique. The dose difference between the measured and calculated doses was 6.8% (191.6 cGy vs. 179.5 cGy) for cases treated with 3DCRT with bolus and artifact correction. The dose difference for cases treated with VMAT and 3DCRT without bolus and with artifact correction was 5.8% (190.2 cGy vs. 179.8 cGy) and 5.6% (193.3 cGy vs. 183.1 cGy), respectively. IMRT with the bolus showed a minimum difference of 0.3% (180.7 cGy vs. 181.3 cGy). Conclusion The presence of the metal port within the TTE in radiation fields resulted to insignificant increased dose differences according to the treatment technique. Future studies should assess whether this dose difference could affect clinical outcomes. Keywords Post-mastectomy radiotherapy · Temporary tissue expander · Metal port · Metal artifact · Dose effect
Introduction A temporary tissue expander (TTE) is a type of skin reconstruction implant which is inserted subcutaneously to result in space between the chest wall and skin [1]. The TTE is constructed using an expander combined with a port injection for maintaining the breast shape and replacing saline. The TTE is replaced with a permanent breast prosthesis at 3–6 months. Post-mastectomy radiotherapy is generally initiated within 4–6 weeks after inserting the TTE. As the * Young Suk Kim [email protected] * Jinhyun Choi [email protected] 1
Department of Radiation Oncology, Jeju National University Hospital, Jeju University College of Medicine, 15, Aran 13‑gil, Jeju‑si, Jeju‑do 63241, South Korea
port is made of high-density materials, such as magnets or titanium, and is included during radiotherapy, it is important to consider the dosimetric effect and artifacts on computed tomography (CT) for ensuring accurate radiation treatment. The dose calculations during radiation treatment planning are influenced by metal
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