System Introduction Radiotherapy and improvement techniques in clinical application

Radiation therapy (RT) is an accepted cornerstone
of oncology treatment.
It is estimated that 40% to 60% of cancer patients will benefit from radiation therapy at some point in the treatment process
.
Adaptive radiotherapy (ART) is a new method by which radiation therapy
can be developed.
With the ART method, computed tomography or magnetic resonance (MR) images are obtained
as part of the treatment delivery process.
This allows the irradiation volume to adapt to changes
in organ and/or tumor location, movement, size, or shape that may occur during treatment.

For oncologists and clinicians outside the radiation oncology profession, the advantages and challenges of ART may be somewhat abstract.

ART is targeted to affect many different types of cancer
.
The use and application of this new technology should be understood by the entire oncology community so that it can be appropriately combined
in the field of cancer treatment.
Again, there is an urgent need to test these advances
.
MR-guided ART (MRgART) is an emerging, extended ART pattern that extends and further enhances the capabilities
of ART.
MRgART offers a unique opportunity
to iteratively improve adaptive image guidance.
However, while the MRgART adaptive process advances ART to levels not previously achieved, it can be more expensive, time-consuming, and complex
.

On November 18, 2021, the team at the Medical College of Wisconsin William A.
Hall published an online presentation in CA: A Cancer Journal for Clinicians (IF=509).
Review article "Magnetic resonance linear accelerator technology and adaptive radiation therapy: An overview for clinicians," which provides clinicians with an overview describing the process of ART, in particular MRgART
。 This review focuses on the concept of adaptive RT (ART) and, more specifically, magnetic resonance (MR)-guided ART (MRgART), which is achieved by integrating an MR imaging (MRI) scanner into a linear accelerator (linacs) for transmitting radiation
.
The aim in this review is to illustrate how this novel RT differs from historical RT and how it is positioned to potentially improve RT-related outcomes
.

Radiation therapy (RT) is an accepted cornerstone
of oncology treatment.
It is estimated that 40% to 60% of cancer patients will benefit from radiation therapy at some point in the treatment process
.
It is estimated that 1.
8 million new cancer cases
occurred in the United States alone in 2020.
This means that about 900,000 of these patients may require radiation therapy
.
The significant impact of this number makes radiotherapy one of
the most common single tumor treatment options for cancer patients.
As a result, meaningful improvements in RT will affect hundreds of thousands of cancer patients
each year.
Studying the best use of radiation therapy is an extremely important part of
understanding the overall progress in cancer treatment.

Historical development of radiation technology over the past 30 years:

Image-guided radiation therapy (IGRT), 2D radiation therapy (2D-RT), 3D-RT, intensity-modulated RT/volumetric modulated arc therapy (IMRT/VMAT), particle therapy, and adaptive therapy (ART).

Like many cancer therapies, RT is rapidly evolving
.
The improvement in RT is the result of
several technological advances.
As computing advances and imaging advances, each of these will have an important impact
on the approach to radiotherapy.
These technological advances attempt to overcome the significant limitations
of RT.
Well-designed, prospective, multi-institutional clinical trials are needed to determine whether proposed advances provide clinical benefit, and methods
to improve RT need to be continuously introduced and evaluated.
Radiation oncologists, medical oncologists, radiologists, clinical trials, and patient advocates need to be aware of these advances in order to test
them in a robust way.

This review focuses on the concept of adaptive RT (ART) and, more specifically, magnetic resonance (MR)-guided ART (MRgART), which is achieved by integrating an MR imaging (MRI) scanner into a linear accelerator (linacs) for transmitting radiation
.
The aim in this review is to illustrate how this novel RT differs from historical RT and how it is positioned to potentially improve RT-related outcomes
.

The use of radiation therapy for many solid tumors remains an important component of
organ-sparing and/or multimodal cancer treatment.
In fact, image guidance has increased the indications
for RT in a variety of situations.
The role of ART, and MRgART in particular, is constantly evolving
.
Here, the review outlines a number of different clinical situations in which ART, and more specifically MRgART, may have a clinical advantage
.
These advantages will include potential reduction in acute and late toxicity, improved local control, and ideally improved OS
for certain malignancies.

Identifying biological rather than strictly anatomical targets represents an exciting aspect of MR-based ART that could have wide-ranging implications, including a shift from the current use of historical radiation doses based on tumor histology and tumor stage, and could lead to imaging response-mediated doses
.
However, oncologists must recognize the need for prospective randomized data to evaluate these types of novel treatment strategies
.
In the future, radiation oncologists may receive a wealth of additional data, including bioimaging data, daily adaptation data, and real-time treatment information
.
The meaning of
this data must be collected, analyzed and understood.
Patient benefits must be quantified and robustly tested
.
Whether this approach ultimately improves clinical outcomes in patients with a variety of malignancies requires extensive prospective evaluation
.

Resources:

https://acsjournals.
onlinelibrary.
wiley.
com/doi/full/10.
3322/caac.
21707

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