Adaptive Radiotherapy
Radiotherapy stands as a cornerstone in cancer treatment, aiming to eradicate cancer cells or impede their progression while mitigating harm to surrounding healthy tissues and organs. Recent technological strides have significantly improved the precision and accuracy of radiotherapy delivery. Nonetheless, anatomical changes such as fluctuations in body weight, shifting of internal organs, and reduction in the size of cancer, during the course of treatment, can change the area being treated.
Adaptive radiotherapy (ART) is a solution that can address potential anatomical variations and do replanning to optimize outcomes. The integration of artificial intelligence (AI) into modern systems has elevated ART to a pivotal role in radiotherapy. It ensures treatment plans are dynamically adjusted to suit the patient’s tumour size on the treatment day, with the frequency of adjustments contingent upon the extent of changes.
ART can be conducted either offline or online. Offline ART requires re simulation & re-planning whereas online ART utilizes specialized technology during sessions. Offline ART mostly addresses systematic and progressive changes that occur during the treatment course, such as patient weight loss and tumor reduction. . Online ART is a process in which the patient’s treatment plan is adjusted before treatment delivery to account for changes detected with the patient in the treatment position. However, even online ART may not be able to capture continuous internal movements of organs during a radiotherapy session since these variations may occur at different time scales ranging from seconds to hours to days. To have in room, tumour tracking Cyberknife is a dedicated machine.
The ART workflow involves capturing images of anatomical changes using existing imaging modalities such as cone-beam computerized tomography (CBCT), in-room CT, MRI, and PET scans. Based on these images, adjustments to dose delivery are calculated, with decisions made after rigorous quality assurance. Presently, AI techniques are leveraged to generate synthetic CT images from CBCT or MRI scans, expediting treatment planning and radiation dose computations while detecting errors.
Numerous initial studies have evaluated ART across various cancers, showing promising outcomes. . Cervical cancer, known for its bladder and rectal mobility changes, demonstrated superior clinical results with ART compared to non-adaptive techniques. Similarly, rectal cancer patients benefited from reduced toxicities with ART. In lung cancer cases, despite respiratory motion and tumor shrinkage, initial clinical results with ART indicated no severe toxicities. ART also proved beneficial in prostate and bladder cancers, improving rectal and bladder doses while maintaining target coverage. In head and neck cancers, although tumor shrinkage and patient weight loss are common, offline ART is a good option for treatment plan adjustment.
In conclusion, ART represents a ground-breaking approach in cancer treatment, harnessing technology and AI to tailor treatment plans dynamically. As advancements continue, the potential for ART to revolutionize cancer care by mitigating treatment-related toxicities and enhancing therapeutic efficacy is vast.