Low dose cone beam CT for paediatric image-guided radiotherapy: Image quality and practical recommendations
Authors
Bryce-Atkinson, AbigailDe Jong, R.
Marchant, Thomas E
Whitfield, Gillian A
Aznar, Marianne Camille
Bel, A
van Herk, Marcel
Affiliation
Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, UKIssue Date
2021
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Purpose: Cone beam CT (CBCT) is used in paediatric image-guided radiotherapy (IGRT) for patient setup and internal anatomy assessment. Adult CBCT protocols lead to excessive doses in children, increasing the risk of radiation-induced malignancies. Reducing imaging dose increases quantum noise, degrading image quality. Patient CBCTs also include 'anatomical noise' (e.g. motion artefacts), further degrading quality. We determine noise contributions in paediatric CBCT, recommending practical imaging protocols and thresholds above which increasing dose yields no improvement in image quality. Methods and materials: Sixty CBCTs including the thorax or abdomen/pelvis from 7 paediatric patients (aged 6-13 years) were acquired at a range of doses and used to simulate lower dose scans, totalling 192 scans (0.5-12.8 mGy). Noise measured in corresponding regions of each patient and a 10-year-old phantom were compared, modelling total (including anatomical) noise, and quantum noise contributions as a function of dose. Contrast-to-noise ratio (CNR) was measured between fat/muscle. Soft tissue registration was performed on the kidneys, comparing accuracy to the highest dose scans. Results: Quantum noise contributed <20% to total noise in all cases, suggesting anatomical noise is the largest determinant of image quality in the abdominal/pelvic region. CNR exceeded 3 in over 90% of cases ≥ 1 mGy, and 57% of cases at 0.5 mGy. Soft tissue registration was accurate for doses > 1 mGy. Conclusion: Anatomical noise dominates quantum noise in paediatric CBCT. Appropriate soft tissue contrast and registration accuracy can be achieved for doses as low as 1 mGy. Increasing dose above 1 mGy holds no benefit in improving image quality or registration accuracy due to the presence of anatomical noise.Citation
Bryce-Atkinson A, De Jong R, Marchant T, Whitfield G, Aznar MC, Bel A, et al. Low dose cone beam CT for paediatric image-guided radiotherapy: Image quality and practical recommendations. Radiotherapy and Oncology. 2021 Oct;163:68–75.Journal
Radiotherapy and OncologyDOI
10.1016/j.radonc.2021.07.027PubMed ID
34343544Additional Links
https://dx.doi.org/10.1016/j.radonc.2021.07.027Type
ArticleLanguage
enae974a485f413a2113503eed53cd6c53
10.1016/j.radonc.2021.07.027
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