Doses de CBCT dos tratamentos de Radioterapia: Quantificação de doses, otimização de protocolos clínicos e de referência de CBCT no Hospital CUF Descobertas

12/02/2024

Introduction: Precision and accuracy in radiotherapy are crucial due to the complexity of radiotheray treatments. CBCT images can be used to verify patient position prior or during treatment. In order to provide reference protocols, for the radiotherapy service, the project's goal is to measure the doses and optimise the imaging protocols by combining high quality images with the lowest feasible dose. Materials and Methods: In order to quantify the dose in each of the three most used clinical imaging protocols measurements were made on two Elekta linear accelerators (linacs) models – VersaHD and Infinity - using the method relying on the CTDI methodology. Qualitative optimization through image quality check of the imaging protocols was performed utilizing a anthropomorphic phantom. Lastly, a qualitative comparison of the obtained images was done using the clinical protocols optimal choices. Results: For protocols 1 to 3, the mean dose reduction was 45%, 35% and 68%, respectively. The low contrast displays a mean MPV result below 2%, 3% and 12% for protocols 1 to 3, respectively. The uniformity presents MPV results below 4%, 2% and 15% protocol 1, 2 and 3 respectively. Consideration should be given to the variations in the X-ray tube brands and its lifetime cycle when comparing the outcomes of the identical image protocols. Conclusions: The results obtained and the analysis carried out lead to the conclusion that dose reduction had small effect to the image quality when carried out with an anthropomorphic phantom.

Authors in the community:

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  A

  André Filipe Dias Lucas

  ist1105807

Supervisors of this institution:

• 

  S

  Salvatore di Maria

  ist25576

physical-sciences - Physical sciences

por - Portuguese

Instituto Superior Técnico