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Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
AlignRT
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
Abstract
This report focuses on the importance of radiation safety and treatment of cancer patients
using VisionRT’s primary product, Align RT. Unlike onboard imaging tools, AlignRt
has a non-ionizing system that uses cameras to detect patient set up and motion. Using
two to three cameras, the patient can be monitored in or outside the room. The
importance of accurate patient set up is discussed along with the goal expose the patient
to the least amount of radiation dose. AlignRT safely monitors the patient and helps
determine proper shifts, while also providing an extra set of eyes for the radiation
therapist. The system automatically holds the radiation beam if the patient’s motion is
outside of the allowed range. The system’s benefits are discussed using recent clinical
evaluations of the product, including one study performed by MD Anderson Cancer
Center in Orlando Florida. These finding showed that AlignRT was more accurate at
determining whole breast radiation therapy shifts when compared to traditional portal
imaging films. Additionally, testimonial statements of AlignRT are included to help
better reflect on how workflow and patient treatments are affected. Overall the research
determines the likelihood that AlignRT will be becoming more popular amongst radiation
therapy centers nationwide.
Keywords: AlignRT, motion management, patient set up.
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
AlignRT
Cancer is one of the deadliest diseases worldwide. 25% of worldwide deaths are
caused by cancer when compared to non-communicable diseases. According to The
American Institute for Cancer Research, cancer causes more deaths than HIV/AIDs,
malaria and TB combined (American Institute of Cancer Research, 2014). There are
many forms of cancer that can be treated with multiple adjuvant therapies such as chemo,
radiation, surgery and targeted therapy or a combination. For the purposes of this
research analysis we will focus on radiation therapy treatment. Radiation therapy can be a
curative and palliative option for patients with cancer. This form of treatment uses highenergy photon beams to shrink cancerous tumors. The treatment is painless and quick but
requires exact patient positioning and treatment planning. Currently, immobilization
devices, tattoos, and daily imaging are all ways to provide accurate patient positioning;
however, there are still ways in which patient set ups can be improved to provide more
accurate treatment.
For radiation therapy, improving patient safety has come a long way. Patients are
expected to be in the exact position that they were in during their simulation.
On board imaging tools such as cone beam CTs (CBCTs) and electronic portal
imagining devices (EPIDs) are used to compare the simulation set up to the everyday
treatment set up. These images can be used to make shifts and move the treatment table,
so the patient is in the position they need to be. These imaging tools are a great way to
make adjustments to patent set up and verify treatment position, however, they do not
detect real time patient movement during treatment. AlignRt, however, is a non-ionizing
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
imaging system capable of detecting movements of the planned target volume for
radiation therapy during treatment.
This system developed in the UK in August of 2001, is Vision RTs primary
product. AlignRT uses two to three cameras and a red patterned light to visualize the
surface of the patient’s body, creating a 3D model for the therapist to monitor. It is
designed to make sure the patient is positioned according to their treatment plan.
AlignRT uses the planned treatment file to create a reference image of the patient.
Depending on the area being radiated, a single or multiple reference point can be
monitored to detect motion. Any motion that is outside of the allowed range will
automatically hold the radiation beam, thus preventing radiation to be delivered to areas
outside of the planned target volume (PTV) (VisionRT, 2015).
The cameras are positioned in two separate viewing points to mimic the way the
human eyes perceive depth. The images can be morphed into a 3D representation of the
patient with a system that uses the disparity of the two viewing points (Image 1). Using
the positions, orientations, and optical properties obtained from the cameras, a 3D image
is acquired and the cameras are calibrated using an algorithm. Once this process is
complete the patient will be “virtually tattooed” with over 20,000 perspective points that
detect motion and create a surface model of the patient’s body (VisionRT, 2015).
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
Image 1. Vision RTs Camera Viewing Points. (VisionRT, 2015).
Radiation therapy is a very precise treatment with very tight margins around the
treated area. Even as little as 1cm can be the difference between treating the targeted area
and treating healthy tissue. It’s proclaimed that any level of radiation dose can produce
some magnitude of detrimental effects. These effects are presumed to cause an increased
risk of genetic mutations and cancer. A standard of care in radiation therapy follows the
protocol A.L.A.R.A. This abbreviation represents the goal to deliver and receive dose
“As Low As Reasonably Achievable” (Environmental Health and Safety Center
Radiation Safety Division). Therefor, any dose to the patient that CAN be avoided,
SHOULD BE. With that said, replacement of portal imaging for patient alignment with
the use of AlignRT would follow the guidelines that radiation therapy aims to achieve.
Improving patient safety is a major focus in every department in health care.
Therefore, a helpful feature of AlignRT is the access to the monitor, keyboard and mouse
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
in both the treatment room and the council. For hypo-fractionated and high dose
radiation treatments this feature is especially useful to ensure the patient can be
supervised from both places. Additionally, AlignRT’s non-ionizing system is beneficial
to patient safety and treatment by decreasing the need for markers, tattoos, and some
immobilization devices. It also protects patients from having any unnecessary irradiation
by holding the beam when the patient’s movement is outside the threshold.
A very important part of all patients’ radiation therapy treatment is the initial set
up. During patient set up, therapist use lasers to line up the patient to their tattoos given in
simulation. Tattoos given on the lateral and central axis of the patient are used to create
an initial reference point where shifts can be applied. This process can take longer with
patients who are unstable and move out of position. With AlignRT, the RT Plan and RT
Struct files allow you to create a reference image of the patient, also using the patient’s
skin contour and isocenter or plan based location. This information then becomes the
DICOM-based reference surface within AlignRT. Additionally with AlignRT, you can
view coordinates that indicate any misalignment using the in-room control. If the patient
moves in any direction, you will observe this movement with real time deltas (RTD) in
all six degrees of freedom (VisonRT, 2015). Motion management is especially important
for patients with lest sided breast cancer.
For patients with left sided breast cancer, dose to the heart is especially important
to monitor and avoid. Techniques such as deep inspiration breath hold (DIBH) can be
used to reduce the volume of heart receiving radiation by increasing the distance between
the heart and the breast or chest-wall (Rong, Walston, Welliver, Chakravarti, & Quick,
2014). AlignRT was shown in a study to be a more reliable surrogate when compared to
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
real–time position management (RPM) alone, which monitors the vertical displacement
of the sternum or abdomen and provides a relative value with respect to the patient’s
breathing baseline. “The RPM alone was not always able to detect intra-fractional
positional changes within the set 5 mm gating window. As a result, if RPM is used as the
only surrogate for DIBH treatment, there may be deviations in the target positioning,
which could result in an unacceptable variation in the accuracy of dose delivery
throughout the treatment course.” It was concluded that AlignRT surface imaging could
be used as an additional tool for patient setup and accurately monitoring inter- and intrafractional motions. The vertical and magnitude RTDs offer linear correlation with the
target position, and can be used as the gating parameter. Overall DIBH was found to be
more accurate with the use of AlignRT with the RPM system (Rong, Walston, Welliver,
Chakravarti, & Quick, 2014).
Even for patients undergoing whole breast radiation therapy (WBRT), Align RT
was more accurate at detecting shifts than traditional portal imaging. In a clinical
evaluation performed at MD Anderson Cancer Center in Orlando Florida, fifty whole
breast cancer patients were set up daily using AlignRT. The alignments made from
AlignRT were compared to a standard mega voltage (MV) portal image and shifts made
from skin marks. When compared to 60% of the treatments, daily shifts made from
Align RT reduced set up error significantly. It was observed that alignment to skin marks
alone in the anterior, posterior directions were noticeably poor compared to the 3D
surface based imaging. For example, the standard deviation of random error recorded the
ant/post direction to be 3.2 mm; where as the superior, inferior and left, right directions
were both 2.2mm. Even though these standard deviations are small, it is important to note
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
because it shows potential to decrease radiation dose to both critical structures of WBRT,
the heart and the lungs (Shah, Amish P. et al, 2013). While patient treatment is very
important to radiation departments, maintaining workflow productivity and patient
satisfaction is also a determining factor before installing a new system.
According to research and development lead radiographer, Clare Hartill,
installation of AlignRT “ happened very quickly, over a couple of days” and “training
was very easy to use and radiographers picked it up pretty quickly.” Another testimonial
from chief radiation therapist, RTT, Matthew Taylor describes AlignRT as an “extra set
of eyes”. He stated the workflow was greatly benefited by AlignRT, especially for the
SRS procedures. These procedures, he explained, were knocked down by a half hour
using the AlignRT for patient set up and motion management (VisionRT, 2015). The
benefits of AlignRT are not going unnoticed. Cancer centers around the country are
investing in the program.
Vision RT systems produce not only AlignRT but also distribute GateCT and
Gate RT, which have all received 510(k) clearance from the FDA to market as class II
medical devices in the USA. Michigan areas such as Detroit, Jackson and Marquette have
all installed VisionRT units. Nearby states such as Ohio, Indiana and Wisconsin are also
users of VisionRT units (VisionRT, 2015). The use of AlignRt is spreading quickly and
becoming more and more talked about amongst radiation therapy centers. The VisonRT
user meeting in Denver, Colorado shared real life clinical examples from therapists
across the country. Their positive messages about the system leave me excited as a fellow
therapist to learn new technology and improve patient set up for the future of radiation
therapy and treatment of cancer.
Running Head: THE IMPROVEMENT OF RADIATION THERAPY USING ALIGN-RT
REFERENCES
American Institute of Cancer Research. ( 2014). Cancer Mortality. Retrieved on 7.24.15
from http://www.aicr.org/learn-more-about-cancer/infographics-
mortality.html
Environmental Health and Safety Center Radiation Safety Division. Radiation Safety
and ALARA. Retrieved on July 25, 2015 from
http://www.ncsu.edu/ehs/radiation/forms/alara.pdf
Rong Y, Walston S, Welliver MX, Chakravarti A, Quick AM (2014) Improving IntraFractional Target Position Accuracy Using a 3D Surface Surrogate for Left Breast
Irradiation Using the Respiratory-Gated Deep-Inspiration Breath-Hold Technique.
PLoS ONE 9(5): e97933. doi:10.1371/journal.pone.0097933.
Shah, Amish P. et al. (2013). Clinical evaluation of interfractional variations for whole
breast radiotherapy using 3-dimensional surface imaging. Practical Radiation
Oncology, Volume 3, Issue 1, 16 – 25.
VisionRT. (2015). Vision RT Ltd. Retrieved on July 24, 2015 from visionrt.com.