Radiotherapy setup deviations in head and neck and prostate tumours: a review

• Autor(a) principal: Simões, Ana Rita
• Data de Publicação: 2012
• Outros Autores: Eiras, Margarida, Grillo, Isabel Monteiro
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://doi.org/10.25758/set.524
• topic: Desvios de posicionamento; Cone-Beam CT; EPID; Precisão; Set-up deviation; Cone-Beam CT; EPID; Accuracy

Background and Purpose – In an era where precision is an increasing necessity in external radiotherapy (RT), modern medical imaging techniques provide means for measuring, quantifying, and evaluating the impact of treatment execution and movement error. The aim of this paper is to review the current literature on the quantification of setup deviations (SD) in patients with head and neck (H&N) or prostate tumors, using Cone Beam Computed Tomography (CBCT) or Electronic Portal Image Device (EPID). Methods – According to the study protocol, MEDLINE/PubMed and b-on databases were searched for trials, which were analyzed using selection criteria based on the quality of the articles. Results – After the assessment of 35 papers, 13 studies were included in this analysis, and nine were authenticated (6 for prostate and 3 for H&N tumors). The SD in the treatment of H&N cancer patients is in the interval of 0.1 to 1.2mm, whereas in prostate cancer this interval is 0.0 to 7.1mm. Discussion – The reproducibility of patient positioning is the most significant barrier to higher precision in RT, which is affected by geometrical uncertainty, positioning errors, and inter or intra-fraction organ movement. There are random and systematic errors associated with patient positioning, introduced since the treatment planning phase or through physiological organ movement. Conclusion – The H&N SD are mostly assigned to the Radiotherapy adverse effects, like mucositis and pain, which affect swallowing and decrease secretions, contributing for the instability of patient positioning during RT treatment and increasing positioning uncertainties. Prostate motion is mainly related to the variation in the bladder and rectal filling. Ignoring SD affects negatively the accuracy of RT. Therefore, detection and quantification of SD are crucial to calculating appropriate margins and the magnitude of the error and improving accuracy in RTE and patient safety.