Efficient and Effective Personalization of PTV Margins During Radiation Therapy for Bladder Cancer

Chen, Susan; Kong, Vickie; Craig, Tim; Chung, Peter; Rosewall, Tara

doi:10.1016/j.jmir.2018.08.002

Cited by 4 publications

(2 citation statements)

References 24 publications

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“…Although planning CT with 15 CBCTs improves target coverage to 95%, it would mean possibly the majority of fractions depending on fractionation would not benefit [57]. Inclusion of the planning CT and initial five CBCTs seems to achieve optimal balance of resources and efficacy [51].…”

Section: Adaptive Radiotherapy Solutions Compositive Volume (Offline Solution)mentioning

confidence: 99%

Image-guided Adaptive Radiotherapy for Bladder Cancer

et al. 2021

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Technological advancement has facilitated patient-specific radiotherapy in bladder cancer. This has been made possible by developments in image-guided radiotherapy (IGRT). Particularly transformative has been the integration of volumetric imaging into the workflow. The ability to visualise the bladder target using cone beam computed tomography and magnetic resonance imaging initially assisted with determining the magnitude of inter-and intra-fraction target change. It has led to greater confidence in ascertaining true anatomy at each fraction. The increased certainty of dose delivered to the bladder has permitted the safe reduction of planning target volume margins. IGRT has therefore improved target coverage with a reduction in integral dose to the surrounding tissue. Use of IGRT to feed back into plan and dose delivery optimisation according to the anatomy of the day has enabled adaptive radiotherapy bladder solutions. Here we undertake a review of the stepwise developments underpinning IGRT and adaptive radiotherapy strategies for external beam bladder cancer radiotherapy. We present the evidence in accordance with the framework for systematic clinical evaluation of technical innovations in radiation oncology (R-IDEAL).

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Section: Adaptive Radiotherapy Solutions Compositive Volume (Offline Solution)mentioning

confidence: 99%

Image-guided Adaptive Radiotherapy for Bladder Cancer

et al. 2021

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“…Many studies report improved sparing of bowel dose volume with ART. 11,14,25,29,30,35,36 Canlas et al 29 While data on CBCT-guided, AI-driven ART are more limited than PoD, there is evidence to support even better dosimetric outcomes with this newer technology. A study looking at pre-treatment planning for 39 pelvic cases, 100 online ART simulations, and five clinical online ART patients conducted on Ethos™ found that auto-generated treatment plans had similar PTV and OAR doses, with more than 75% AI segmentations requiring no or minor editing, and adaptive plan superiority in 88% of cases.…”

Section: Pod Adaptationmentioning

confidence: 99%

Adaptive Radiotherapy for Bladder Cancer – A Review

Livschitz,

Liu,

Schaal

et al. 2024

EMJ Urol

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Radiotherapy plays an important role in organ preservation for bladder cancer. Delivering radiation accurately can be challenging, in part because the bladder and surrounding organs may change position, volume, and shape between and during the fractions of a treatment course. This variability has been accounted for by increasing the margins around the treatment targets, which can expose more normal tissue to radiation, and increase the likelihood of normal tissue complications. An alternative strategy is to alter, or adapt, the radiotherapy treatment plan to account for such inter-fraction changes, a strategy termed ‘adaptive radiotherapy’ (ART). ART allows smaller target volumes to be treated, and may reduce complications. Approaches to ART include offline adaptation strategies and online strategies, which includes choosing a plan of the day (PoD) based on pre-treatment imaging and magnetic resonance (MR), or with cone-beam CT (CBCT)-guided daily plan re-optimisation. Here, the authors review these ART strategies and trials exploring the dosimetric and clinical benefits of ART relative to non-ART bladder radiotherapy.

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Patient‐specific adaptive planning margin for whole bladder radiation therapy

Zhang,

Liu,

Donaghue

et al. 2024

J Applied Clin Med Phys

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BackgroundWhole bladder irradiation is an organ preservation treatment approach for muscle‐invasive bladder cancer (MIBC). Conventional planning margins, typically 15–20 mm, increase normal tissue toxicity and limit possible dose escalation.PurposeThe study aimed to develop a patient‐specific adaptive margin recipe for whole bladder irradiation to minimize the planning target volume (PTV) while preserving adequate dose coverage.MethodsSixteen patients who received whole‐bladder irradiation were retrospectively selected for this study. We proposed a patient‐specific anisotropic adaptive margin recipe, derived from the first five fractions of kV‐CBCTs, to account for inter‐fractional bladder changes. This recipe was validated using kV‐CBCTs from fractions six to ten and the final five fractions. The goal was to achieve a residual volume, defined as the percentage of daily bladder volume (Vdaily) outside the PTV, of less than 5%. Adaptive and conventional plans were created using proposed and conventional margins, respectively. A dosimetric comparison of targets and organs‐at‐risk (OARs) was performed between the two approaches.Results(Vdaily) decreased throughout the treatment course. The most notable inter‐fractional bladder variations were in the superior and anterior directions. The patient‐specific anisotropic adaptive margins, averaging 6 mm (± 2.9 mm), achieved a residual volume of less than 5%. Compared to conventional planning, the adaptive approach reduced PTV volume by an average of 135.3 cc (± 46.6 cc). A significant correlation (p < 0.05) was identified between residual volume and adaptive margins in the anterior, superior, left, and right directions. Using the proposed adaptive margins, the median residual volume was 0.71% (interquartile range 0.09%−3.55%), and the median (Vdaily) receiving the prescribed dose was 99.1% (interquartile range 95.3%−99.9%). Adaptive plans demonstrated superior OAR sparing compared to conventional plans.ConclusionsThe proposed patient‐specific adaptive margin recipe for whole bladder irradiation resulted in margins smaller than conventional ones, optimized normal tissue sparing, and maintained adequate PTV coverage.

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Efficient and Effective Personalization of PTV Margins During Radiation Therapy for Bladder Cancer

Cited by 4 publications

References 24 publications

Image-guided Adaptive Radiotherapy for Bladder Cancer

Image-guided Adaptive Radiotherapy for Bladder Cancer

Adaptive Radiotherapy for Bladder Cancer – A Review

Patient‐specific adaptive planning margin for whole bladder radiation therapy

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