Корисник:PetarBoshkovski/Adaptive Radiotherapy

Adaptive radiotherapy (ART) is an innovative approach in the field of radiotherapy that utilizes advanced imaging technologies and intelligent algorithms to automatically adjust radiotherapy plans in real time. This methodology enables individualized treatments aimed at improving the precision and effectiveness of radiotherapy while simultaneously minimizing the adverse effects on healthy tissues.

Radiotherapy in a patient with head and neck cancer.

The main goal of ART is to improve the effects of radiotherapy in cancer patients. By dynamically adjusting radiotherapy plans based on changes in patient anatomy and tumor characteristics, this technique aims to maximize radiation dose delivery to the tumor while minimizing exposure to surrounding healthy tissues. By enabling a personalized and precise approach to treatment, adaptive radiotherapy enhances patients' quality of life and treatment outcomes, making it critically important in modern medical practice.

Components of ART

The principle of ART is based on technical components in three main areas: image guidance/tracking, dose verification, and plan adaptation.

Image guidance

The role of images is significant in every aspect of radiotherapy, from determining the stage of the disease, contouring structures, treatment planning, verification, to treatment response and evaluation. In the field of ART, image guidance provides input information and visualization of anatomy, enabling determination of how daily anatomy differs from the radiotherapy plan. Image guidance typically involves two phases: acquiring three-dimensional images and image registration.

Verification dose

Dose verification is a mechanism used to obtain information about the dosimetric accuracy of fractionated treatment. In ART, dose verification is performed through a process of daily dose verification and analysis of cumulative dose.

Plan adaptation

This represents a significant part of the process. It is based on using information obtained from image guidance as input, helping to reduce differences between planned and actual patient anatomy. The main goal is to achieve optimal coverage of the target area and protect organs at risk. This involves various methods and protocols that can be classified into 4 main groups: online repositioning, offline replanning, online adaptation, and hybrid plan adaptation strategies.

I. Online Repositioning

According to Wu et al. (2011), this is the first stage of adaptive radiotherapy used in clinics equipped with Image Guided Radiotherapy (IGRT) technology. Through this process, the patient's position is corrected in real-time using daily images, with possible adjustments to the target from the planned anatomy. Additionally, Chung et al. (2004) describe methods and techniques utilizing fiducial markers and computer tomographic images for soft tissue alignment. However, online repositioning alone is not sufficient for complete correction of dosimetric deficits due to daily changes in the target area.

II. Offline Replanning

Offline replanning, according to Wu et al. (2011), involves the process in adaptive radiotherapy where a new treatment plan is created, upgraded, or modified from the previously made plan. This replanning occurs offline, meaning not during the patient's treatment session. The application of offline replanning allows physicians to analyze data and modify the treatment plan at an appropriate time before the next treatment phase. This may involve dose corrections, changes in the target area, or other aspects of the plan to improve the efficiency and safety of radiotherapy.

III. Online Adaptation

This technique, used in ART, identifies daily anatomical changes before treatment initiation. It involves various real-time optimization methods on daily anatomical structures. Some techniques include modifying the multileaf collimator (MLC), allowing adaptation of its position concerning the target area.

IV. Hybrid Plan Adaptation Strategies

These strategies combine different techniques to correct daily anatomical changes, aiming for optimal coverage of the target area and organ-at-risk protection. They are most effective when combining online repositioning with offline/online optimization. This can result in further margin reduction to 2.00mm for patients with low to medium-risk prostate cancer, respectively, covering the target area by 99%.

Adaptive Radiotherapy for Anatomical Changes

Adaptive radiotherapy for anatomical changes refers to the approach used to identify variations in patient anatomy between treatment planning and execution, as well as during the course of radiotherapy. These changes can occur in various forms such as changes in patient posture, tumor motion, weight loss, or tumor regression. Additionally, anatomical changes refer to changes in various time scales, from seconds for cardiac and respiratory motion to minutes for bladder filling and peristaltic motion, as described by Sonke et al. (2019).

To address these anatomical changes, adaptive radiotherapy utilizes feedback from images to quantify and modify treatment plans according to new anatomical conditions. This allows for increased accuracy and precision in radiation delivery, potentially resulting in reduced toxicity to surrounding healthy tissues, improved tumor control, and dose optimization.

Clinical Application of Adaptive Radiotherapy

In clinical practice, adaptive radiotherapy (ART) is applied as a personalized treatment for various types of cancer. In the treatment of prostate cancer, ART is effective in managing changes in anatomical position and target size between fractions, resulting in better coverage of target areas and reduced toxicity to surrounding healthy tissues. Albosaabar et al. (2024) highlight head and neck cancer treatment as "one of the most complex and precise strategies due to the small and overlapping structures in this body part and its radiosensitivity." ART for head and neck cancer is used to adapt treatment plans to significant anatomical changes due to patient weight loss. The potential implementation of adaptive radiotherapy for cancer in other locations, such as the kidneys and bladder, is being explored as a strategy to improve clinical outcomes and personalized treatment. With each new implementation, adaptive radiotherapy opens up new opportunities for the development of clinical protocols and improvement in patient care.

Future Development

In the future, adaptive radiotherapy will continue to advance as an important part of oncological treatment. From the perspective of technological innovations and advancements in radiological technology, new advanced algorithms and methods for automatic adaptation of treatment plans according to patients' anatomical changes are expected to be developed. This will enable particularly precise and individualized treatment to improve clinical outcomes and reduce the risk of adverse effects of therapy.

References

[[Категорија:Radiotherapy]] [[Категорија:Radioterapija]] [[Категорија:Adaptive Radiotherapy]]