Why Liver Tumors May Be Better Treated With Radiotherapy Upright
The Leo Cancer Care Upright Patient Positioning System
One of the driving factors for developing our upright positioning technology for delivering Radiation Therapy to cancer tumours was to mirror the way most of us live our lives – in the upright position.
After all, from the minute we get up in the morning we spend our days either walking, standing or sitting. In fact, two-thirds of our time is spent this way.
Targeting cancer tumours in the upper body requires precision. However, lying down to receive Radiation Therapy does not appear to be the most natural way to do this, especially when it comes to internal movement of our organs.
Part of our mission is to build technology whereby a patient has a level of comfort and stability that allows for both their dignity to remain intact and to receive successful treatment. Our determination to be able to provide upright treatment for a wide range of upper body tumours has been triggered by various research papers that have specifically looked at how much motion there is inside and outside the body while undergoing radiation treatment.
The gravity of the situation
Approximately 36,000 people get liver cancer in the United States each year, and about 28,000 succumb from the disease. Liver cancer is also prevalent globally and the outcomes are even more dismal. Liver tumours are one such area where we hope our system will ultimately be of benefit to cancer patients around the world. We believe, and are increasingly providing the evidence along with other major research bodies, that the position of our organs remains largely unchanged in the upright position.
Currently, for radiation therapy treatment, patients are asked to lie down and in so doing, the direction of gravity to the internal organs, including the liver, changes. For those requiring treatment for liver cancers, there are a number of factors that can make this even more problematic.
Research reveals a large margin for change
A study was conducted with 12 volunteers by the Switzerland-based Paul Scherrer Institute (PSI).
The research paper, published in 2007, Systematic errors in respiratory gating due to intrafraction deformations of the liver, Martin von Siebenthal, Gábor Székely, Antony J. Lomax, Philippe C. Cattin was one of those that inspired our goal. It found that when we are lying parts of the liver drifts for up to 35 minutes moving in some cases up to 20 millimetres. In terms of targeting, this is a considerable shift and means that without careful monitoring, a tumour could move out of the treatment field causing healthy tissue around it to be hit by the radiation beam, thus damaging it.
While respiratory gating effectively compensated for the respiratory motion within short sequences (three minutes), deformations after 20 minutes from the setup position of more than 5mm in seven of the 12 subjects in some parts of the liver were recorded.
Liver lobules consist of rows of liver hepatocyte cells which are in close contact with blood-filled sinusoids and also lie adjacent to canaliculi into which bile is secreted. Macroscopically, the liver is more like bread dough than a fluid filled container like the bladder or stomach. This structure makes it takes many minutes for the liver to deform in response to a change in the direction of gravity.
A moving target hinders accuracy
The study concluded that measurements over a few breathing cycles should not be used as proof of accurate reproducibility of motion, not even with the same fraction, if it is longer than a few minutes.
We think that, because the direction of gravity is not changing, the amount of liver drift in the upright position will be less than the results from this PSI study. Although, we don’t have all the answers yet, the Institute is currently carrying out tests to determine upright benefits. We feel that in the future there is huge potential for liver cancer patients to receive better treatment accuracy from having their radiation therapy in the upright position.
Watch our explainer video here:
Why liver tumors may be better treated with radiotherapy upright. Our goal is to deliver better treatment accuracy by enabling patients to remain upright for their treatments.
Please note: The Leo Cancer Care technology is not commercially available and will not treat patients until the required regulatory approval has been achieved.