Normal tissue sparing in a phase II trial on daily adaptive plan selection in radiotherapy for urinary bladder cancer

Vestergaard, A.; Muren, L.P.; Lindberg, Henriette; Jakobsen, Kathrine Kronberg; Petersen, Jørgen B. B.; Elstrøm, U.V.; Agerbæk, Mads; Høyer, Morten

doi:10.3109/0284186x.2014.928419

Cited by 63 publications

(88 citation statements)

References 43 publications

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“…Patients were treated with an empty bladder for all fractions, and received 48 Gy to the lymph nodes, 60 Gy to the bladder and an additional 10 Gy tumor boost dose. Both strategies have been described in further detail previously [3,6,11]; the CBCT-strategy was a combination of the strategy as described by Vestergaard et al [6], and an unpublished dose escalation study.…”

Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

“…Schematic representation for the two adaptive strategies. The left panel shows the CBCT-based strategy [6] and the right panel shows the CT-based strategy [3]. Margins to create the PTV volumes from the library of structures are listed in Table 1.…”

Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

“…fractions could then be used to generate the contours needed to create the adaptive plans [6] (Figure 1), which were used from the second week onwards. Patients were treated with an empty bladder for all fractions, and received 48 Gy to the lymph nodes, 60 Gy to the bladder and an additional 10 Gy tumor boost dose.…”

Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

“…In general, two ART strategies are currently applied to obtain target volumes for the multiple plans: using multiple planning CT scans [3][4][5], or using the CBCT scans acquired during the first week of treatment [5][6][7]. Currently, no consensus exists regarding the best adaptive strategy.…”

mentioning

confidence: 99%

“…Recently, it has been shown that adaptive radiotherapy (ART) may reduce normal tissue dose by selecting an optimal plan from a patient-specific plan library, according to daily patient anatomy [3][4][5][6][7]. Several plan selection strategies have been proposed, all of which are based on creating multiple treatment plans prior to or during treatment, by imaging multiple anatomical variations [3][4][5][6][7]. For every treatment fraction, the plan best fitting the daily bladder volume as assessed on cone beam computed tomography (CBCT) is selected.…”

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confidence: 99%

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A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

et al. 2016

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Background Adaptive radiotherapy is introduced in the management of urinary bladder cancer to account for day-to-day anatomical changes. The purpose of this study was to determine whether an adaptive plan selection strategy using either the first four cone beam computed tomography scans (CBCT-based strategy) for plan creation, or the interpolation of bladder volumes on pretreatment CT scans (CT-based strategy), is better in terms of tumor control probability (TCP) and normal tissue sparing while taking the clinically applied fractionation schedules also into account. Material and methods With the CT-based strategy, a library of five plans was created. Patients received 55 Gy to the bladder tumor and 40 Gy to the non-involved bladder and lymph nodes, in 20 fractions. With the CBCT-based strategy, a library of three plans was created, and patients received 70 Gy to the tumor, 60 Gy to the bladder and 48 Gy to the lymph nodes, in 30-35 fractions. Ten patients were analyzed for each adaptive plan selection strategy. TCP was calculated applying the clinically used fractionation schedules, as well as a rescaling of the dose from 55 to 70 Gy for the CT-based strategy. For rectum and bowel, equivalent doses in 2 Gy fractions (EQD2) were calculated. Results The CBCT-based strategy resulted in a median TCP of 75%, compared to 49% for the CT-based strategy, the latter improving to 72% upon rescaling the dose to 70 Gy. A median rectum V30Gy (EQD2) of 26% [interquartile range (IQR): 8-52%] was found for the CT-based strategy, compared to 58% (IQR: 55-73%) for the CBCT-based strategy. Also the bowel doses were lower with the CT-based strategy. Conclusions Whereas the higher total bladder TCP for the CBCT-based strategy is due to prescription differences, the adaptive strategy based on CT scans results in the lowest rectum and bowel cavity doses.

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Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

Section: Plan Selection Strategies and Fractionationmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

et al. 2016

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Triggering daily online adaptive radiotherapy in the pelvis: Dosimetric effects and procedural implications of trigger parameter‐value selection

Yock,

Ahmed,

Masick

et al. 2023

J Applied Clin Med Phys

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BackgroundOnline adaptive radiotherapy (ART) can address dosimetric consequences of variations in anatomy by creating a new plan during treatment. However, ART is time‐ and labor‐intensive and should be implemented in a resource‐conscious way. Adaptive triggers composed of parameter‐value pairs may direct the judicious use of online ART.PurposeThis work analyzed our clinical experience using CBCT‐based daily online ART to demonstrate how a conceptual framework based on adaptive triggers affects the dosimetric and procedural impact of ART.MethodsSixteen patients across several pelvic sites were treated with CBCT‐based daily online ART. Differences in standardized dose metrics were compared between the original plan, the original plan recalculated on the daily anatomy, and an adaptive plan. For each metric, trigger values were analyzed in terms of the proportion of treatments adapted and the distribution of metric values.ResultsTarget coverage metrics were compromised due to anatomic variation with the average change per treatment ranging from ‐0.90 to ‐0.05 Gy, ‐0.47 to ‐0.02 Gy, ‐0.31 to ‐0.01 Gy, and ‐12.45% to ‐2.65% for PTV D99%, PTV D95%, CTV D99%, and CTV V100%, respectively. These were improved using the adaptive plan (‐0.03 to 0.01 Gy, ‐0.02 to 0.00 Gy, ‐0.03 to 0.00 Gy, and ‐4.70% to 0.00%, respectively). Increasingly strict triggers resulted in a non‐linear increase in the proportion of treatments adapted and improved the distribution of metric values with diminishing returns. Some organ‐at‐risk (OAR) metrics were compromised by anatomic variation and improved using the adaptive plan, but changes in most OAR metrics were randomly distributed.ConclusionsDaily online ART improved target coverage across multiple pelvic treatment sites and techniques. These effects were larger than those for OAR metrics, suggesting that maintaining target coverage was our primary benefit of CBCT‐based daily online ART. Analyses like these can determine online ART triggers from a cost‐benefit perspective.

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Empirical analysis of a plan‐of‐the‐day strategy to approximate daily online reoptimization for prostate CBCT‐guided adaptive radiotherapy

Yock,

Cooney,

Morales‐Paliza

et al. 2023

J Applied Clin Med Phys

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PurposeAdaptive radiotherapy (ART) can improve the dose delivered to the patient in the presence of anatomic variations. However, the required time, effort, and clinical resources are intensive. This work analyzed a plan‐of‐the‐day (POD) approach on clinical patients treated with online ART to explore implementations that balance dosimetric benefit and clinical resource cost.MethodsEight patients treated to the prostate and proximal seminal vesicles with 26 fractions of CBCT‐guided, daily online ART were retrospectively analyzed. With a plan library composed of daily adaptive plans from the initial week of treatment and the original plan, the effect of a POD approach starting the following week was investigated by simulating use of these previously generated plans under 3‐ and 6‐degree‐of‐freedom patient alignment. The plan selected for each treatment was that from the library that maximized the Dice similarity coefficient of the clinical target volume with that of the current treatment fraction. The resulting distribution of several target coverage and organ‐at‐risk dose metrics are described relative to those achieved with the daily online reoptimized adaptive technique.ResultsThe values of target coverage and organ‐at‐risk dose metrics varied across patients and metrics. The POD schemas closely approximated the reference values from a fully reoptimized adaptive plan yet required less than 20% of the reoptimization effort. The POD schemas also had a much greater effect on target coverage metrics than 6‐degree‐of‐freedom registration did. Organ‐at‐risk dose metrics also varied considerably across patients but did not exhibit a consistent dependence on the particular schema.ConclusionsPOD schemas were able to achieve the vast majority of the dosimetric benefit of daily online ART with a small fraction of the online reoptimization effort. Strategies like this might allow for more practical and strategic implementation of ART so as to benefit a greater number of patients.

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Normal tissue sparing in a phase II trial on daily adaptive plan selection in radiotherapy for urinary bladder cancer

Abstract: Daily adaptive plan selection in RT of bladder cancer results in a considerable normal tissue sparing, of a magnitude that we expect will translate into a clinically significant reduction of the treatment-related morbidity.

Cited by 63 publications

References 43 publications

A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

Triggering daily online adaptive radiotherapy in the pelvis: Dosimetric effects and procedural implications of trigger parameter‐value selection

Empirical analysis of a plan‐of‐the‐day strategy to approximate daily online reoptimization for prostate CBCT‐guided adaptive radiotherapy

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