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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5525_Библиотеки_им_академика_М_И_Перельмана.pdf
X
- •Foreword
- •Acknowledgments
- •Editor biographies
- •Yi Wang
- •X. Sharon Qi
- •List of contributors
- •1.2.3 Feature engineering and representation
- •1.2.4 Linear separability
- •1.2.5 Classical models
- •1.1 A brief introduction to AI
- •1.2 Machine learning basics
- •1.2.1 Learning paradigms
- •1.3 Artificial neural networks
- •1.3.1 Feed-forward neural networks
- •1.3.2 Recurrent neural networks
- •1.3.3 Convolutional neural networks
- •1.3.4 Attention
- •1.3.5 Training neural networks
- •1.3.6 Applications and use cases of deep learning
- •1.4 Model training and evaluation
- •1.4.1 Hyperparameters
- •1.4.2 Data split
- •1.4.3 Evaluation metrics
- •1.5 Generative models
- •1.5.1 Generative adversarial networks
- •1.5.2 Diffusion models
- •1.5.3 Applications and use cases
- •1.6 Ethical consideration and bias
- •1.6.1 Transparency and explainability
- •1.6.2 Bias and fairness
- •1.6.3 Data privacy violation
- •1.6.4 Risk and misuse
- •1.7 Summary
- •References
- •2.1 Introduction
- •2.1.2 Staff roles in radiation therapy
- •2.2 Overview of AI in radiation therapy
- •2.2.1 Patient evaluation and dose prescription
- •2.2.2 Treatment simulation
- •2.2.3 Contouring
- •2.2.4 Treatment planning
- •2.2.5 Quality assurance
- •2.2.6 Treatment delivery
- •2.2.7 Response assessment and toxicity management
- •2.3 Summary
- •3.1 Introduction
- •3.1.1 Introduction of clinical decision making and AI
- •3.1.2 The role of AI in clinical decision making
- •3.2 AI algorithms for clinical decision making
- •3.2.2 Radiomics
- •3.2.3 Data integration by AI
- •3.2.4 Interpretability of AI models
- •3.3 Application of AI in clinical decision making
- •3.3.1 Diagnosis and disease phenotyping
- •3.3.2 Personalized treatment
- •3.3.3 Treatment outcome and prognosis prediction
- •3.4 Challenges and future directions of AI in clinical decision making
- •3.4.1 Challenges and concerns
- •3.4.2 Future directions
- •3.5 Summary
- •References
- •4.1 Introduction
- •4.2 Imaging for treatment planning
- •4.2.1 CT simulation
- •4.2.2 4D-CT
- •4.2.3 PET/CT
- •4.2.4 MRI
- •4.3 Imaging for treatment guidance
- •4.3.1 Portal imaging
- •4.3.2 CBCT
- •4.3.3 CT-on-rail and CT-linac
- •4.3.4 MR-linac
- •4.3.5 PET-linac
- •4.4 Imaging for motion management
- •4.4.1 ExacTrac
- •4.4.2 Varian triggered imaging
- •4.4.3 4D-CBCT
- •4.4.4 Cine MRI
- •4.4.5 4D-MRI
- •4.4.6 Surface imaging
- •4.5 Imaging for treatment assessment
- •4.5.1 Contrasted CT
- •4.5.2 PET/CT
- •4.5.3 Functional MRI
- •4.6 Summary
- •5.1 Introduction to big data in radiation oncology
- •5.1.1 Overview of big data
- •5.1.2 Sources of big data in radiation oncology
- •5.1.3 Big data and AI in radiation oncology
- •5.2 Big data lifecycle in radiation oncology
- •5.2.1 Data aggregation and storage
- •5.2.2 Data sharing and security
- •5.4 The application of big data in radiation oncology
- •5.4.1 Medical image segmentation
- •5.4.2 Automatic treatment planning
- •5.4.3 Treatment response prediction
- •5.4.4 Quality assurance and patient safety
- •5.4.5 Clinical decision support
- •5.2.3 Data visualization
- •5.2.4 Knowledge creation and implementation
- •5.2.5 Data archiving and deletion
- •5.3 Big data analytics with AI
- •5.3.1 Data processing and integration
- •5.3.2 AI modeling
- •5.5 Challenges and future perspectives
- •5.6 Summary
- •Reference
- •6.1 The road to ART
- •6.1.1 3D conformal radiotherapy (3DCRT)
- •6.1.2 Intensity modulated radiotherapy (IMRT)
- •6.1.3 Image-guided radiotherapy (IGRT)
- •6.1.4 Adaptive radiotherapy (ART)
- •6.2 ART workflow and implementation
- •6.2.2 Current practice
- •6.2.3 Clinical impact
- •6.3 Considerations for implementing online ART
- •6.3.1 Time as a limiting factor
- •6.3.2 Implications for fast and reliable re-planning
- •6.3.4 Clinical considerations
- •6.4 Summary
- •7.1 Components of ART workflow
- •7.1.1 Simulation
- •7.1.2 Pre-planning
- •7.1.3 Online imaging and daily re-planning
- •7.1.4 Quality assurance
- •7.2 AI-driven ART
- •7.2.1 Simulation
- •7.2.2 Pre-planning
- •7.2.3 AI for delivery
- •7.3 Outlook and future directions
- •7.3.1 Real-time ART with AI
- •7.3.2 Dose escalation and functional adaption with AI
- •7.4 Summary
- •References
- •8.1 Introduction
- •8.2 Synthetic CT: deep learning methods
- •8.2.1 Conventional methods
- •8.2.2 U-Net
- •8.2.3 Generative adversarial networks
- •8.2.4 Denoising diffusion probabilistic model
- •8.3 Synthetic CT from CBCT
- •8.3.1 Noise and artifact reduction
- •8.3.2 Online dose calculation
- •8.3.3 Online image segmentation
- •8.4 Synthetic CT from MRI
- •8.4.1 Synthetic image accuracy
- •8.4.2 Dose calculation in MR-only radiation therapy
- •8.4.3 PET attenuation correction
- •8.4.4 Image registration
- •8.5 Discussion and outlook
- •8.6 Summary
- •References
- •9.1 AI-based image registration and segmentation for ART
- •9.1.1 Adaptive radiation therapy
- •9.2 Artificial intelligence
- •9.2.1 What is machine learning?
- •9.2.2 What is deep learning?
- •9.3 Deep learning: the basic components
- •9.3.1 Convolutional neural networks: looking at the picture
- •9.3.2 Pooling layers: keeping what matters most
- •9.3.3 Fully connected (dense) layers: bringing it all together
- •9.3.4 Activations
- •9.3.5 Loss: driving the model
- •9.3.6 Auto-encoders: remove the noise
- •9.3.7 Supervised versus unsupervised learning
- •9.3.8 Pre-trained convolutional neural networks
- •9.4 Image registration: bringing two images together
- •9.4.1 Registration similarity metrics
- •9.4.2 Types of registrations
- •9.5 AI-based image registration
- •9.5.1 Supervised learning
- •9.5.2 Unsupervised learning
- •9.5.3 Registration in ART
- •9.5.4 Commonalities in architectures
- •9.6 Image segmentation
- •9.6.1 Introduction: coloring by the numbers
- •9.6.2 Segmentation networks
- •9.6.3 Best practices
- •9.7 Summary
- •10.1 Introduction
- •10.1.1 Overview of chapter content
- •10.2 The landscape of AI-assisted dose prediction
- •10.2.1 Traditional machine learning for dose prediction
- •10.2.2 Deep learning-based dose prediction
- •10.2.3 Challenges in AI-assisted dose prediction
- •10.3 Re-planning workflows powered by AI
- •10.3.1 Deep learning for re-planning pipelines
- •10.4 Future directions of AI-assisted dose prediction and re-planning
- •10.5 Summary
- •11.1 Introduction
- •11.2.1 Imaging-based motion monitoring
- •11.2.2 Delivery system actions
- •11.2.3 Challenges for real-time ART implementation
- •11.3 AI in real-time ART workflows
- •11.3.1 Improving intrafraction motion monitoring through AI
- •11.3.2 Mitigating system latency through AI
- •11.4 AI for ART delivery: future directions
- •11.4.1 Management of non-respiratory motion
- •11.4.2 Training AI models with small or unpaired datasets
- •11.4.4 Biology-guided ART delivery
- •11.5 Summary
- •References
- •12.1 Introduction
- •12.2 Patient QA
- •12.2.1 Pre-planning QA
- •12.2.2 Pre-treatment plan QA
- •12.2.3 On-treatment QA
- •12.3 Treatment delivery systems and instruments
- •12.3.1 Machine commissioning
- •12.3.2 Machine QA
- •12.3.3 Dosimetry tool QA
- •12.4 Summary
- •References
- •13.1 Data resources for response modeling in radiotherapy
- •13.1.1 Clinical data
- •13.1.2 Imaging (radiomics)
- •13.1.3 Treatment planning (dosiomics)
- •13.1.4 Multiomics
- •13.2 Radiotherapy treatment outcome modeling
- •13.2.1 TCP/NTCP in radiotherapy
- •13.2.2 Clinical outcomes versus PROs
- •13.2.3 Machine learning response prediction
- •13.2.4 Explainability of ML response models
- •13.2.5 Sample use cases
- •13.3 AI response-based adaptive radiotherapy
- •13.3.1 Requirements and challenges
- •13.3.2 Prediction versus treatment optimization
- •13.3.3 Sample use cases
- •13.4 Challenges and recommendations
- •13.5 Summary
- •Acknowledgments
- •References
- •14.1 Overview of challenges in AI-driven ART
- •14.2 Data challenges
- •14.2.1 Data availability
- •14.2.2 Data quality
- •14.2.3 Data privacy
- •14.3 Technical challenges
- •14.3.2 Model robustness and generalizability
- •14.3.3 Model explainability and interpretability
- •14.4 Challenges associated with online and real-time workflows
- •14.4.1 Image quality
- •14.4.2 Dose calculation
- •14.4.3 Real-time ART
- •14.5 Operational challenges
- •14.5.1 Clinical validation
- •14.5.3 Staff training
- •14.5.4 User experiences
- •14.5.5 Quality management program
- •14.5.6 Financial challenges
- •14.6 Ethical, regulatory, and legal challenges
- •14.6.1 Ethical issues
- •14.6.2 Regulatory and legal issues
- •14.7 Summary
- •References
- •15.1 Clinical considerations for CT-based offline ART
- •15.1.1 Patient and site selection
- •15.1.2 Re-simulation
- •15.1.3 Re-planning
- •15.1.4 Plan summation and evaluation
- •15.1.6 Limitations and future directions
- •15.2 Clinical considerations for CBCT/CT-based online ART
- •15.2.2 Patient and site selection
- •15.2.3 Simulation
- •15.2.4 Pre-planning review
- •15.2.5 Reference planning
- •15.2.9 Limitations and future directions
- •15.3 Summary
- •References
- •16.1 Introduction
- •16.2 Overview of MRI-guided ART systems
- •16.3 MRI-guided ART workflow
- •16.4 AI applications for MRI-guided ART
- •16.4.1 Synthetic CT generation
- •References
- •16.4.2 Auto-segmentation
- •16.4.3 Image registration
- •16.4.4 Others
- •16.4.5 Future AI development and implementation
- •16.5 Summary
- •17.1 Functional PET-guided ART
- •17.1.1 PET-based functional imaging overview
- •17.1.2 From anatomy to function: the power of PET in radiation therapy
- •17.1.5 Conclusions and future prospects
- •17.2 Functional MRI-guided ART
- •17.2.1 From anatomy to function: the power of functional MRI in radiation therapy
- •17.2.4 Conclusion and future prospects
- •17.3 Summary
- •References
- •18.1 Proton ART
- •18.1.1 Clinical context and necessity
- •18.1.2 Patient populations
- •18.1.4 Rationale for AI in proton ART
- •18.2 AI in proton ART
- •18.2.1 Imaging
- •18.2.2 Deformable and rigid registration
- •18.2.3 Contour propagation
- •18.2.4 Dose calculations
- •18.2.5 Plan optimization
- •18.2.6 Other developments
- •18.3 Implementation of adaptive proton therapy
- •18.4 Summary
- •References
- •19.1 Designing clinical trials with AI
- •19.1.1 The essential role of clinical trials
- •19.1.2 Trial protocols and methodologies
- •19.1.3 AI-driven clinical trial design and execution
- •19.1.4 Incorporation of digital twins (DTs) in clinical trials
- •19.2 Implementation of AI in ongoing clinical trials
- •19.2.1 Integration with existing clinical trial frameworks
- •19.2.2 Quality assurance, compliance, and standardization
- •19.3 Case studies of AI in adaptive radiotherapy trials
- •19.3.1 Overview of guidance for advanced radiotherapy in clinical trials
- •19.3.2 AI in the radiotherapy clinical trial quality assurance processes
- •19.4 Ethical and regulatory considerations
- •19.4.1 Patient consent and data privacy
- •19.4.2 Bias, fairness, and transparency
- •19.4.3 Regulatory guidelines and compliance
- •19.5 Future directions and challenges
- •19.5.1 Emerging technologies and techniques
- •19.5.2 Alternative strategies
- •19.6 Conclusion
- •19.7 Summary
- •References
- •20.1 Risk management
- •20.1.1 Prospective risk assessments
- •20.1.2 Root cause analysis

Artificial Intelligence in Adaptive Radiation Therapy
changes [3]. The highly dynamic nature of real-time ART demands AI models that
can keep pace with the fast-moving components of the treatment delivery system.
Compared to online ART, real-time ART requires far greater performance on AI
tools, where even minor delays in image processing, motion predictions, or treatment adaptation could compromise treatment efficacy and patient outcomes.
Conquering these real-time performance challenges involves not only speed but
also accuracy and robustness. Significant further advancements in neural network
architecture, enhanced computational efficiency, and rigorous validation are necessary to ensure the seamless and reliable integration of AI into real-time ART
workflows.
14.5 Operational challenges
Integrating AI into ART is a complex undertaking that introduces several operational challenges. These challenges stem from the intricacies involved in incorporating any AI systems into clinical workflows, the requirement for extensive training
and education for healthcare professionals, and the necessity to maintain a seamless
operation within a high-stakes clinical environment.
14.5.1 Clinical validation
The clinical validation of AI models for ART poses significant challenges, primarily
due to the lack of standardized evaluation metrics and criteria [34]. Unlike traditional medical devices and software, AI models require rigorous validation to ensure
their safety, efficacy, and reliability. In ART, where online and real-time decisions
can directly impact patient outcomes, the stakes are particularly high. The lack of
standardization complicates the process of model evaluation across different disease
sites, clinical settings, and patient populations. This variability can lead to inconsistencies in evaluation results, making it difficult to determine an AI model’s true
clinical utility. Moreover, the dynamic nature of ART, which involves continuous
adaptation to patient-specific changes (e.g. patient anatomy and tumor characteristics), necessitates that AI models undergo extensive testing in diverse and evolving
scenarios. For example, an auto-segmentation model for online ART treating
bladder cancer will need to manage varying levels of bladder fillings [2].
To address these challenges, establishing standardized evaluation metrics and
criteria is essential. Collaborative efforts involving government agencies (e.g. the US
FDA, NIH, NCI), professional societies (e.g. AAPM and ASTRO), clinical users,
research investigators, and industrial vendors are essential to establish standardized
qualitative and quantitative evaluation metrics and methods [25, 34, 35].
Additionally, creating and sharing large, annotated datasets representative of
diverse patient populations can improve the robustness and generalizability of AI
models. Implementing rigorous testing protocols that simulate real-world clinical
scenarios can further enhance the reliability of AI systems in ART. The streamlined
clinical validation process can lead to safer and more effective AI-driven ART.
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14.5.2 Workflow integration
Integrating AI into ART is not as simply as adding a new tool into the existing
process. Most of the current online ART platforms operate within closed-loop
systems using proprietary software, allowing only vendor-approved AI models and
their authorized collaborators to integrate into the clinical workflow [12, 17]. As a
result, inserting any alternative or new AI tools into the closed-loop workflow is
challenging, if not impossible. Data extraction from the online ART system is
difficult, and even if access is granted, the data transfer between the ART platform
and third-party software is time-consuming and prone to communication errors (e.g.
incomplete transfer of DICOM data). This substantial limitation and the associated
liability issues discourage researchers and developers from investing in independent
AI tools for online ART. The challenge is even more significant for real-time ART,
where immediate adjustments to treatment delivery systems are required [1].
It is also technically challenging to integrate the closed-loop online ART platform
with existing clinical systems, particularly when they are provided by different
vendors. Varian Ethos, as the most popular CBCT-based online ART platform, has
been widely implemented in all Varian environments using the Eclipse treatment
planning system (TPS) and ARIA record and verification (R&V) system [17]. Such
an integration, although not yet seamless, has been thoroughly examined by the
vendor during the design, manufacturing, and evaluation processes. While it has
been demonstrated that the Ethos system can work with other TPSs (e.g. RayStation
by RaySearch Laboratories, Stockholm, Sweden) and R&V systems (e.g. MOSAIQ
by Elekta, Stockholm, Sweden), such a non-uniform integration requires special
attention for data transfer, and increases the manpower and resources needed for
maintenance [29].
14.5.3 Staff training
Providing ART team members with adequate training on basic concepts of AI and
the specific AI tools involved in the ART workflow is an essential requirement for
successful clinical implementation [36]. First, much of the current workforce in
radiation therapy did not receive formal education or training in AI. The
introduction of AI into clinical practice represents a significant paradigm shift,
requiring the ART team members to acquire new competencies and understand
complex AI-driven processes. This gap necessitates substantial investment in training programs designed to bridge the knowledge divide [37]. Effective training should
encompass both theoretical understanding of AI concepts and practical skills for
operating AI systems. Second, AI is a rapidly evolving field, with new algorithms,
techniques, and tools emerging continuously. Practitioners must stay current with
the latest advancements to utilize AI effectively and safely in ART. Continuous
education is essential to ensure that practitioners are up to date with the latest
developments and best practices. This need for ongoing learning requires a commitment to professional development and access to updated educational resources.
Institutions and professional organizations play a critical role in facilitating
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Artificial Intelligence in Adaptive Radiation Therapy
continuous education, ensuring that ART professionals are equipped with the latest
knowledge and best practices [38].
Developing and implementing comprehensive training and continuing education
programs can be resource-intensive and time-consuming, presenting a significant
barrier for individual institutions. Therefore, it is important for professional
organizations (e.g. AAPM, ASTRO, and ESTRO) to offer formal AI training
through regular workshops, courses, and access to current literature, and provide
certificate to demonstrate competency on practicing AI in clinical settings [18]. By
tackling these challenges, the ART workforce can harness the full potential of AI in
ART, ultimately improving patient outcomes.
14.5.4 User experiences
Successful implementation of AI in ART requires collaboration and coordination
among various stakeholders, including radiation oncologists, medical physicists, IT
professionals, and administrators. Each group brings a unique perspective and set of
expertise to the table, and effective communication and teamwork are essential to
address the multifaceted challenges posed by AI integration. Establishing clear roles,
responsibilities, and lines of communication can help facilitate smoother collaboration and ensure that all stakeholders are aligned in their goals and objectives [39].
Distinctive from many other RT technologies, ART is mostly executed in a closelooped software environment provided by the vendor of the treatment machine. In
such a highly integrated system, it is impractical, if not impossible, to use any AI
model trained or refined by institutional data. Despite the variations in clinical
practice between different institutions (e.g. contouring, planning), all users of ART
need to use the same AI model provided by the vendor [25]. Therefore, this puts
additional burden on medical physicists (who often take charge of the clinical
implementation of ART) to gain their fellow radiation oncologists’ trust in the
results provided by the vendor models. While clinicians often appreciate the
efficiency gain provided by AI, they may want to maintain clinical consistency
between their adaptive and non-adaptive patients. Therefore, when introducing
ART, the medical physicists should provide clear guidance on how to facilitate the
clinicians to achieve clinical consistency while not losing the efficiency gain [40].
14.5.5 Quality management program
Establishing robust quality assurance (QA) and monitoring processes to continuously track AI model performance, detect potential errors, and ensure ongoing
safety and efficacy is essential [39]. This includes developing contingency plans for
situations where AI systems fail or produce unexpected results, ensuring that
clinicians can seamlessly revert to conventional treatment approaches or seek
alternative decision support mechanisms.
Failure mode and effects analysis (FMEA), a systematic approach to identifying
and mitigating potential failures, can play a crucial role in ensuring the safe and
effective integration of AI into ART workflow. The FMEA framework is documented in the American Association of Physicists in Medicine’s (AAPM) Task
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Group 100 (TG-100) report [41]. FMEA can identify potential failure modes,
analyze their potential impacts on patient safety and treatment outcomes, and
prioritizes actions to mitigate those risks. AAPM TG-100 outlined how to develop
and implement quality management programs [42]. For an AI-driven ART
program, the team should optimize the allocation of resources towards preventing
the most substantial risks indicated by the FMEA. Moreover, AAPM TG-100
provided important guidance on how to build effective quality management tools,
such as checklists. Once properly implemented, FMEA can safeguard every step in
the ART workflow in which AI plays important roles, from data collection and
model development to clinical deployment and maintenance. Integration of FMEA
as an organic part of AI development in ART will also help foster a culture of safety
and trust among different role groups (e.g. physicians, physicists, dosimetrists, and
therapists) [42].
The most common AI application in online ART is auto-segmentation of online
images, typically CBCT or MR images [43]. FMEA could help identify vulnerabilities in the clinical workflow and provide insights for quality improvements.
AAPM TG-275 suggested that errors in target and organ delineation ranked among
the highest failure modes, as inaccurate segmentation could jeopardize tumor
control and increase the risk of complications [44]. Contouring errors originating
from AI-generated contours could go undetected during the planning and review
process, despite the required review by physicians and physicists. This risk would
become even more significant in online ART, when the clinical team is under
enormous pressure to minimize the time interval between imaging and treatment. To
mitigate this risk, it is crucial to develop a robust QA tool to catch such errors.
Relying on human consciousness in manual checks is not enough to minimize such
a risk in online ART [45]. A potential solution is implementing a secondary
automated system capable of identifying discrepancies between the physician-edited
primary contour and an independently generated secondary auto-contour, thereby
enhancing safety and accuracy in online ART.
14.5.6 Financial challenges
ART requires more initial financial investment into hardware, software, personnel
training, and other recourses. The highly complex clinical workflow also requires
more manpower and treatment machine time. Consequently, each adaptive treatment session is more costly than a conventional, non-adaptive session [46]. However,
as of 2025, ART is not assigned a specific Current Procedural Terminology (CPT)
code by the US Center for Medicare and Medicaid Services (CMS), meaning there is
no dedicated reimbursement mechanism under Medicare, and billing for this
technology is considered a ‘gray area’ with most practices likely including the
additional work within existing treatment codes. Essentially, providers are not
currently receiving separate payment for the adaptive component of radiation
therapy treatment.
The financial implications of AI implementation in ART cannot be overlooked,
either. The integration of AI tools into ART workflow significantly reduces the time
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Artificial Intelligence in Adaptive Radiation Therapy
required for each session, resulting in faster treatment adaptation and potentially
better clinical outcomes. Despite these operational advantages, investments in AI
technologies, including hardware, software, and training, represent a significant
financial commitment. The lack of clear reimbursement guidelines further complicates the financial viability of AI implementation, adding constraints on its
adoption, ongoing use, and maintenance within ART workflow. Given the considerable capital and operational costs involved, healthcare institutions must carefully
evaluate the cost–benefit ratio to ensure that the expected improvements in treatment precision and workflow efficiency justify the investment. Successfully implementing AI in ART requires strategic planning, securing appropriate funding, and
optimizing resource allocation to sustain long-term benefits [47].
14.6 Ethical, regulatory, and legal challenges
The ethical, regulatory, and legal considerations of using AI in ART are complex
and multifaceted. Addressing these challenges requires a collaborative approach
involving healthcare professionals, AI vendors, professional societies, regulatory
agencies, and legal experts. By fostering an environment of transparency, accountability, and innovation, the potential of AI in ART can be harnessed to improve
patient outcomes while upholding ethical principles and legal standards.
14.6.1 Ethical issues
A variety of ethical issues must be carefully addressed to ensure responsible and
equitable use of the AI technologies in ART. A primary ethical issue is the potential
for bias within AI algorithms [48]. AI systems are trained on data that may reflect
historical biases or inequities, leading to suboptimal outcomes for under-represented
patient populations. For example, prostate cancer is one of the disease sites most
frequently treated using ART. Black patients exhibit higher PSA levels and Gleason
score > 6 compared to white patients [49]. Addressing these biases requires diligent
efforts in the collection, curation, and validation of diverse datasets that accurately
represent all patient demographics. Ensuring transparency in the development and
deployment of AI systems is crucial to build trust and confidence among both
patients and healthcare professionals.
Furthermore, maintaining human oversight on AI under significant time pressure
is a unique challenge for online ART [36]. When decisions must be made rapidly,
ART practitioners may feel compelled to lower their ethical standards for oversight
to expedite the treatment process. This urgency can lead to insufficient scrutiny of
AI-generated contours and plans, potentially resulting in errors that could have been
avoided with more thorough evaluation. Furthermore, there is a risk that clinicians
might favor the adaptive re-plan over the original plan due to financial incentives,
even when the re-plan offers no clear clinical advantage. This raises concerns about
the integrity of decision-making. Additionally, the reliance on AI systems in timesensitive scenarios might inadvertently diminish the role of human judgment and
expertise, leading to over-reliance on technology. To address these ethical challenges, it
is crucial to establish robust guidelines and training programs that emphasize the
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Artificial Intelligence in Adaptive Radiation Therapy
importance of maintaining high ethical standards in oversight, regardless of time
constraints [18]. Transparency in the financial incentives associated with treatment
decisions should also be ensured to prevent conflicts of interest.
14.6.2 Regulatory and legal issues
Healthcare institutions must navigate a complex landscape of regulatory requirements related to data privacy, including the Health Insurance Portability and
Accountability Act (HIPAA) in the United States, the General Data Protection
Regulation (GDPR) in Europe, and other national and international regulations.
Compliance with these regulations requires continuous monitoring and adaptation
of data protection practices to meet evolving legal standards [25]. In the United
States, AI models used in ART workflow may require model-specific approval from
the US Food and Drug Administration (FDA). While it is the vendor’s responsibility to obtain initial 510(k) clearance and maintain continuing compliance, it is the
medical physicist’s responsibility to verify the approval and compliance, particularly
when preparing for initial commissioning and major model or software upgrades.
Moreover, the medical physicists need to establish a quality management program
to ensure that the local use of the AI models follows the regulatory approval and
vendor recommendation. Any customized use of the integrated AI tools should
undergo through evaluation in consultation with the vendor. The use of third-party
or research AI tools without approval from the primary vendor may not only pose
significant clinical risks, but also jeopardize regulatory compliance. Similarly,
research that seeks to alter the standard workflow of the AI solutions also needs
to be designed and applied with great caution.
The deployment of AI in ART raises several legal concerns that must be
addressed to mitigate risks and ensure compliance with applicable laws and
regulations [50]. One prominent legal issue is liability in the event of errors or
adverse outcomes. Determining liability can be complex when AI systems are
involved in clinical decision-making. Legal frameworks must clarify the responsibilities and accountability of various stakeholders, including AI developers, healthcare providers, and institutions. Establishing clear guidelines for the documentation
and reporting of AI-driven decisions is essential to facilitate transparency and
accountability in clinical practice. Additionally, legal considerations extend to data
protection and privacy laws that govern the collection, storage, and use of patient
data in AI systems. Legal frameworks must also address cross-border data transfers
and international collaborations, providing guidelines for the secure and compliant
exchange of data in a global healthcare landscape.
14.7 Summary
In conclusion, the journey towards the effective implementation of AI in ART is
marked by challenges spanning the data, technical, operational, as well as ethical,
regulatory, and legal domains. Overcoming these challenges requires a multidisciplinary approach with strong collaboration among healthcare providers, data
scientists, AI vendors, professional societies, and regulatory bodies. As technologies
14-14

Artificial Intelligence in Adaptive Radiation Therapy
continue to evolve, the synergy between AI and ART is poised to revolutionize
radiation therapy paradigms, offering more precise, effective, and personalized
cancer care.
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14-17

IOP Publishing
Artificial Intelligence in Adaptive Radiation Therapy
Yi Wang and X. Sharon Qi
Chapter 15
Offline computed tomography-based and online
cone beam computed tomography-based
adaptive radiation therapy
Joel A Pogue, Natalie Viscariello, Dennis N Stanley, Joseph Harms,
Richard A Popple and Carlos E Cardenas
Adaptive radiotherapy (ART) encompasses offline and online approaches to adjust
treatment plans based on anatomical and physiological changes during the course of
radiotherapy. This chapter reviews the clinical considerations, technical workflows,
and current limitations of both offline computed tomography (CT)-based and online
cone beam computed tomography (CBCT)-based ART (figure 15.1). Offline ART
workflows involve re-simulation and re-planning triggered by observed anatomical
changes, with dose recalculation aided by deformable registration or synthetic CT
generation. Online CBCT-guided ART systems, such as Varian Ethos, Elekta Evo,
and United Imaging’s uRT-linac, enable real-time plan adaptation with on-board
imaging and fast optimization engines. Key challenges include image quality, synthetic
CT accuracy, increased workload, and quality assurance (QA) without interrupting
clinical throughput. The integration of AI, knowledge-based planning, and adaptive
triggers offers new avenues for workflow efficiency and clinical impact. This chapter
provides practical guidance for the implementation, patient selection, and QA
strategies essential for the successful clinical deployment of both ART paradigms.
15.1 Clinical considerations for CT-based offline ART
Radiation therapy is generally delivered over the c ourse of weeks. During this
time, patient anatomy may change, potentially impacting target coverage and
delivery of unnecessary dose to surrounding tissues. Common examples of changes
that impact the delivered dose distribution include tumor regression, weight loss,
changes in swelling, and variable organ filling. In response to these changes, offline
adaptive radiation therapy (ART) may be employed to ensure that patients are
treated as initially intended. Offline ART consists of taking a repeat CT simulation
during the course of an RT course and re-optimizing the treatment plan. The ART
doi:10.1088/978-0-7503-6119-4ch15 15-1 ª IOP Publishing Ltd 2025. All rights,
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