Safety and Efficiency Analysis of Operational Decision-Making During Cone Beam Computed Tomography-Based Online Adaptive Radiation Therapy.

PURPOSE: Cone beam computed tomography (CBCT)-based online adaptive radiation therapy (ART) is especially beneficial for patients with large interfractional anatomic changes. However, treatment planning and review decisions need to be made at the treatment console in real-time and may be delegated to clinical staff whose conventional scope of practice does not include making such decisions. Therefore, implementation can create new safety risks and inefficiencies. The objective of this work is to systematically analyze the safety and efficiency implications of human decision-making during the treatment session for CBCT-based online ART. METHODS AND MATERIALS: The analysis was performed by applying the Systems-Theoretical Process Analysis technique and its extension for human decision-making. Four centers of different CBCT-based online ART practice models comprised the analysis team. RESULTS: The general radiation therapy control structure was refined to model the interactions between routine treatment delivery staff and in-person or remote support staff. The treatment delivery staff perform 6 key control actions. Eighteen undesirable states of those control actions were identified as affecting safety and/or efficiency. In turn, 97 hazardous clinical scenarios were identified, with the control action "prepare and position patient" having the least number of scenarios and "delineate/edit influencer and target structures" having the most. Five of these are specific to either in-person or remote support during the treatment session, and 12 arise from staff support in general. CONCLUSIONS: An optimally safe and efficient online ART program should require little to no support staff at the treatment console to reduce staff coordination. Uptraining of the staff already at the treatment console is needed to achieve this goal. Beyond the essential knowledge and skills such as contour editing and the selection of an optimal plan, uptraining should also target the specific cognitive biases identified in this work and the cognitive strategies to overcome these biases. Additionally, technological and organizational changes are necessary.

Cone-beam computed tomography-guided online adaptive radiotherapy is feasible for prostate cancer patients.

Background and purpose: Studies have shown the potential of cone-beam computed tomography (CBCT)-guided online adaptive radiotherapy (oART) for prostate cancer patients in a simulation environment. The aim of this study was to evaluate the feasibility of the clinical implementation of CBCT-guided oART for prostate cancer patients. Materials and methods: Between February and July 2020, eleven prostate cancer patients were treated with CBCT-guided oART using a fractionation scheme of 20 × 3 Gy to the prostate and 20 × 2.7/3.0 Gy to the seminal vesicles for more advanced stages. The on-couch adaptive workflow consisted of influencer (prostate, seminal vesicles, rectum, bladder) review, target review, scheduled (re-calculated) and adapted (re-optimized) plan generation, an independent QA procedure and treatment delivery. Treatment time, proportion of adapted fractions and reasons for plan adaptation were evaluated. Results: Mean total treatment time (±SD) from CBCT acquisition to end of treatment delivery was 17.5 ±â€¯3.2 min (range: 10.8-28.8 min). In all 220 fractions, the PTV coverage was increased for the adapted plan compared to the scheduled plan. The V60Gy of bladder and rectum were below the constraints (<5% and <3%) for both scheduled and adapted plans in 171 out of 220 fractions and for the adapted plan only in 30 out of 220 fractions. In 19 out of 220 fractions, the V60Gy of the bladder and/or rectum was above the constraint for the adapted plan. Conclusions: The clinical implementation of CBCT-guided oART is feasible for prostate cancer patients. The adaptive workflow is possible within twenty minutes on average with a dedicated team.

Role of endocavitary brachytherapy with or without chemotherapy in cancer of the nasopharynx.

PURPOSE: We previously reported our preliminary experience with nasopharyngeal cancer boosted after 60-70 Gy external beam radiotherapy (EBRT) by fractionated endocavitary brachytherapy (ECBT) to cumulative doses of 78-82 Gy. As for Stage III-IVB disease, cisplatin (CDDP)-based neoadjuvant chemotherapy (CHT) was given. The aim of the present study was to define the role of ECBT more accurately. METHODS AND MATERIALS: Ninety-one patients with primary nasopharyngeal cancer, staged according to the 1997 UICC/AJCC classification system, were treated between 1991 and 2000 with 60-70 Gy external beam radiotherapy and 11-18 Gy ECBT. Of the 91 patients, 21 were treated in conjunction with CHT and 70 without CHT. Tumors were subdivided into undifferentiated (UD) and well, moderately, and poorly differentiated (WMP-D) subtypes. Treatment results were analyzed for local control (LC), disease-free survival (DFS), freedom from distant metastasis, and overall survival (OS). RESULTS: A univariate and multivariate Cox regression analysis found stage, treatment period, age, and grade significant for LC, DFS, and OS. At 2 years, for Stage I-IIB (1st period, 1991-1996), the LC, DFS, and OS were 96%, 88%, and 80%, respectively, vs. 65%, 46%, and 52% for Stage III-IVB. For the 2nd treatment period (1996-2000; CHT for Stage III-IVB), the LC, DFS, and OS at 2 years was 100%, 90%, and 61% (Stage I-IIB), respectively, vs. 86%, 74%, and 66% (Stage III-IVB). Three prognostic groups (PGs) were constructed. For the 1991-1996 period, at 2 years, patients in the good PG (UD Stage I-IIB disease) had 100% LC and 92% OS; those in the intermediate PG (UD Stage III-IVB or WMP-D Stage I-IIB), had 94% LC and 71% OS; and those in the poor PG (WMP-D Stage III-IVB) had 47% LC and 40% OS. For the 1996-2000 period, at 2 years, the good PG had 100% LC and 88% OS; the intermediate PG had 100% LC and 64% OS; and the poor PG had 71% LC and 60% OS. CONCLUSION: For Stage I-IIB disease treated between 1991 and 2000, at 3 years, the LC and OS was 97% and 67%, respectively. The results with 77-81 Gy without CHT warrant EBRT combined with ECBT to remain our standard of care for Stage I-IIB disease. For N2-3 and/or T3-4 tumors, in addition to high doses of RT, neoadjuvant CHT was administered as of 1996. For the 1991-2000 period, at 3 years, the LC was 86% and the OS was 72% with CHT, with little extra morbidity; they were 68% and 35% without CHT. Because of better target coverage and sparing, T3-4 tumors are currently boosted by stereotactic RT to 81.2 Gy.