How Remaining Upright for Liver Treatment May Impact Liver Position

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. It is said that 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 quality 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 to 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 the evidence from major research bodies suggests, that the position of some 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 indicates 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 could hinder  

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 believe that, because the direction of gravity is not changing, the amount of liver drift in the upright position could be less than the results from this PSI study. Although we don’t have all the answers yet, the Institute plans to carry out tests to determine upright benefits.

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Please note: The Leo Cancer Care technology is not yet commercially available.