Browsing by Author "Simonds, Hannah M."
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- ItemFully automatic treatment planning for external-beam radiation therapy of locally advanced cervical cancer : a tool for low-resource clinics(American Society of Clinical Oncology, 2019) Kisling, Kelly; Zhang, Lifei; Simonds, Hannah M.; Fakie, Nazia; Yang, Jinzhong; McCarroll, Rachel; Balter, Peter; Burger, Hester; Bogler, Oliver; Howell, Rebecca; Schmeler, Kathleen; Mejia, Mike; Beadle, Beth M.; Jhingran, Anuja; Court, LaurencePURPOSE: The purpose of this study was to validate a fully automatic treatment planning system for conventional radiotherapy of cervical cancer. This system was developed to mitigate staff shortages in low-resource clinics. METHODS: In collaboration with hospitals in South Africa and the United States, we have developed the Radiation Planning Assistant (RPA), which includes algorithms for automating every step of planning: delineating the body contour, detecting the marked isocenter, designing the treatment-beam apertures, and optimizing the beam weights to minimize dose heterogeneity. First, we validated the RPA retrospectively on 150 planning computed tomography (CT) scans. We then tested it remotely on 14 planning CT scans at two South African hospitals. Finally, automatically planned treatment beams were clinically deployed at our institution. RESULTS: The automatically and manually delineated body contours agreed well (median mean surface dis- tance, 0.6 mm; range, 0.4 to 1.9 mm). The automatically and manually detected marked isocenters agreed well (mean difference, 1.1 mm; range, 0.1 to 2.9 mm). In validating the automatically designed beam apertures, two physicians, one from our institution and one from a South African partner institution, rated 91% and 88% of plans acceptable for treatment, respectively. The use of automatically optimized beam weights reduced the maximum dose signiﬁcantly (median, −1.9%; P , .001). Of the 14 plans from South Africa, 100% were rated clinically acceptable. Automatically planned treatment beams have been used for 24 patients with cervical cancer by physicians at our institution, with edits as needed, and its use is ongoing. CONCLUSION: We found that fully automatic treatment planning is effective for cervical cancer radiotherapy and may provide a reliable option for low-resource clinics. Prospective studies are ongoing in the United States and are planned with partner clinics.
- ItemHypofractionation and prostate cancer : a good option for Africa?(AOSIS, 2017-08-29) Incrocci, Luca; Heijmen, Ben; Kupelian, Patrick; Simonds, Hannah M.Cancer is an emerging public health problem in Africa. According to the World Health Organization, the numbers will be doubled by 2030 because of the ageing and the growth of the population. Prostate cancer is the most common cancer among men in most African countries. Radiotherapy machines are extremely limited in Africa and therefore prostate cancer in Africa is mostly managed by urologists. However, for a large proportion of prostate cancer patients, external-beam radiotherapy (EBRT) will be the treatment of choice in Africa because of limitations of surgical expertise in many countries. The disparity between the α/β ratio for late complications and the low α/β ratio for prostate cancer widens the therapeutic window when treating prostate cancer with hypofractionation. Because of the reduced number of treatment days, hypofractionation offers economic and logistic advantages, reducing the burden of the very limited radiotherapy resources in most African countries. It also increases patient convenience. A misleading assumption is that high-level radiotherapy is not feasible in low-income countries. The gold standard option for hypofractionation includes daily image-guided radiotherapy with 3–4 implanted gold fiducials. Acceptable methods for image guidance include ultrasound and cone-beam computed tomography (CT). CT-based treatment planning with magnetic resonance imaging fusion allows for accurate volume delineation. Volumetric modulated arc therapy or inversely planned intensity modulated radiotherapy is the ideal for treatment delivery. The most vital component is safe delivery, which necessitates accurate quality assurance measures and on-board imaging. We will review the evidence and potential utilisation of hypofractionated EBRT in Africa.
- ItemA retrospective analysis of the effect of planning tumour volume on survival in cervical carcinoma(Medpharm Publications, 2018) Fourie, Ilze; Simonds, Hannah M.Introduction: Locally advanced stages of invasive cervical cancer (ICC) are associated with poor outcomes; factors influencing survival include increased tumour volume. In resource-constrained settings access to diagnostic imaging with CT and MRI is limited. Alternative methods of establishing tumour volume can be defined with use of the planning target volume (PTV) delineated prior to radiotherapy. The aim of this study is to determine whether increased PTV size impacted on overall survival in a cohort of cervical cancer patients with Stage IIB/IIIB disease who completed radical radiotherapy. Materials and methods: A retrospective analysis was undertaken of patients with histologically confirmed Stage IIB/IIIB ICC treated with radical radiotherapy. Exclusion criteria included patients who did not complete prescribed radiotherapy and brachytherapy. Demographic and treatment details were collected. Planning target volumes were retrieved. Kaplan–Meier analysis was used to calculate the overall survival rate. A multivariate Cox proportional hazard model was derived to assess associations with all-cause mortality. Results: A total of 71 patients met the inclusion/exclusion criteria. The median PTV was 653 cc. On univariate analysis factors significantly associated with a lower overall survival included HIV positivity and the presence of hydronephrosis. Increased PTV size paradoxically showed a trend to improved overall survival. On multivariant analysis HIV status, advanced stage, hydronephrosis and a smaller PTV were significantly related to higher all-cause mortality. Conclusion: It is concluded that, when using planning target volumes, the hypothesis that larger volumes impact on overall survival was disproved. A larger cohort and more accurate methods of determining tumour volume, including PET/CT, will be considered in future prospective studies.
- ItemA risk assessment of automated treatment planning and recommendations for clinical deployment(American Association of Physicists in Medicine, 2019-06) Kisling, Kelly; Johnson, Jennifer L.; Simonds, Hannah M.; Zhang, Lifei; Jhingran, Anuja; Beadle, Beth M.; Burger, Hester; Du Toit, Monique; Joubert, Nanette; Makufa, Remigio; Shaw, William; Trauernicht, Christoph; Balter, Peter; Howell, Rebecca M.; Schmeler, Kathleen; Court, LaurencePurpose: To assess the risk of failure of a recently developed automated treatment planning tool, the radiation planning assistant (RPA), and to determine the reduction in these risks with implementation of a quality assurance (QA) program specifically designed for the RPA. Methods: We used failure mode and effects analysis (FMEA) to assess the risk of the RPA. The steps involved in the workflow of planning a four-field box treatment of cervical cancer with the RPA were identified. Then, the potential failure modes at each step and their causes were identified and scored according to their likelihood of occurrence, severity, and likelihood of going undetected. Additionally, the impact of the components of the QA program on the detectability of the failure modes was assessed. The QA program was designed to supplement a clinic's standard QA processes and consisted of three components: (a) automatic, independent verification of the results of automated planning; (b) automatic comparison of treatment parameters to expected values; and (c) guided manual checks of the treatment plan. A risk priority number (RPN) was calculated for each potential failure mode with and without use of the QA program. Results: In the RPA automated treatment planning workflow, we identified 68 potential failure modes with 113 causes. The average RPN was 91 without the QA program and 68 with the QA program (maximum RPNs were 504 and 315, respectively). The reduction in RPN was due to an improvement in the likelihood of detecting failures, resulting in lower detectability scores. The top-ranked failure modes included incorrect identification of the marked isocenter, inappropriate beam aperture definition, incorrect entry of the prescription into the RPA plan directive, and lack of a comprehensive plan review by the physician. Conclusions: Using FMEA, we assessed the risks in the clinical deployment of an automated treatment planning workflow and showed that a specialized QA program for the RPA, which included automatic QA techniques, improved the detectability of failures, reducing this risk. However, some residual risks persisted, which were similar to those found in manual treatment planning, and human error remained a major cause of potential failures. Through the risk analysis process, we identified three key aspects of safe deployment of automated planning: (a) user training on potential failure modes; (b) comprehensive manual plan review by physicians and physicists; and (c) automated QA of the treatment plan.