Publicação
Improving medical imaging handling for radiotherapy using Velocity
| Resumo: | The first step in Intensity Modulated Radiation Therapy (IMRT) treatments is to acquire a Computed Tomography (CT) to plan Radiation Therapy – the planning CT (pCT). Thereafter, before an image guided session of EBRT, a Cone Beam CBCT is acquired making sure the patient is correctly positioned as was while acquiring the pCT. However, there are frequent changes in shape and size of different organs during treatment, meaning that the planned dose might not be the delivered. If these changes are significant, a treatment re-plan may be required, which is time consuming. This situation can be avoided, since re-planning is sometimes taken as precaution due to specialist uncertainty about the exact distribution of the delivered dose. Deformable image registration (DIR) is a possible solution to know the dose distribution throughout the entire treatment. The latter can be performed by deforming the planning CT on each daily CBCT and posteriorly calculate the actual delivered dose using the reshaped CT’s. It is not advisable to use the CBCT’s due to the low quality of image. In this project, the benefits of using DIR on clinic are going to be explored, by firstly evaluating DIR quality on pelvic CT-CBCT scans. The study cases enrolled in this dissertation were diagnosed with cervical or endometrial cancer. These patients accepted being part of a clinical study implemented at and approved by the ethical commission of Champalimaud Foundation, which suggests the implementation of Stereotactic Body Radiation Therapy (SBRT) instead of Brachytherapy, to avoid tumour recurrence. Using DIR, it is also going to be analysed the deformation magnitude and consistency of these patients during treatment as well as calculated the actual delivered dose to the PTV and CTV. For DIR purposes, it is going to be use Velocity® in this project, a software developed by Varian Medical Systems. The study cases planning CT’s are going to be deformed to the CBCT form using two DIR methods: one intensity-based and one intensity-based and feature based. For dose calculation purposes, Eclipse (Varian Medical Systems) is going to be used. |
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| Autores principais: | Silva, Mafalda Mantero Morais Duarte |
| Assunto: | Radioterapia Tomografia Computorizada Tomografia Computorizada de Feixe Cónico Registo Deformável de Imagens Cancro ginecológico Teses de mestrado - 2018 |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | The first step in Intensity Modulated Radiation Therapy (IMRT) treatments is to acquire a Computed Tomography (CT) to plan Radiation Therapy – the planning CT (pCT). Thereafter, before an image guided session of EBRT, a Cone Beam CBCT is acquired making sure the patient is correctly positioned as was while acquiring the pCT. However, there are frequent changes in shape and size of different organs during treatment, meaning that the planned dose might not be the delivered. If these changes are significant, a treatment re-plan may be required, which is time consuming. This situation can be avoided, since re-planning is sometimes taken as precaution due to specialist uncertainty about the exact distribution of the delivered dose. Deformable image registration (DIR) is a possible solution to know the dose distribution throughout the entire treatment. The latter can be performed by deforming the planning CT on each daily CBCT and posteriorly calculate the actual delivered dose using the reshaped CT’s. It is not advisable to use the CBCT’s due to the low quality of image. In this project, the benefits of using DIR on clinic are going to be explored, by firstly evaluating DIR quality on pelvic CT-CBCT scans. The study cases enrolled in this dissertation were diagnosed with cervical or endometrial cancer. These patients accepted being part of a clinical study implemented at and approved by the ethical commission of Champalimaud Foundation, which suggests the implementation of Stereotactic Body Radiation Therapy (SBRT) instead of Brachytherapy, to avoid tumour recurrence. Using DIR, it is also going to be analysed the deformation magnitude and consistency of these patients during treatment as well as calculated the actual delivered dose to the PTV and CTV. For DIR purposes, it is going to be use Velocity® in this project, a software developed by Varian Medical Systems. The study cases planning CT’s are going to be deformed to the CBCT form using two DIR methods: one intensity-based and one intensity-based and feature based. For dose calculation purposes, Eclipse (Varian Medical Systems) is going to be used. |
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