New 4D Scanning Technique to Preserve Lung Function in Cancer Patients

[caption id="attachment_5398" align="alignright" width="292"] The black and white CT scan (left) shows a lung cancer (blue arrow) partially surrounded by expanded and apparently aerated lung; the PET scan (right) shows the expanded lung without corresponding blood flow (red arrow), meaning this lung is not effectively contributing to breathing[/caption]
Radiation oncologists from Melbourne’s Peter MacCallum Cancer Centre have  reported the results of a world-first study evaluating a new planning technique to guide more personalised radiation treatment of lung cancer by minimising exposure to healthy lung tissue.
Revealing details of 4D VQ PET imaging to plan treatment of non-small cell lung cancer, Dr Shankar Siva, lead of the clinical trial, says by viewing blood movement and airflow, radiation oncologists will now be able to more accurately target cancer cells and limit exposure to highly functioning areas of the lung that should be avoided to preserve optimal breathing capacity.
‘Using conventional 4D CT scans, we could view the anatomical detail and movement of the lung, but we would plan radiation therapy thinking all areas of the  lung were contributing equally to the patient’s breathing," Dr Siva said. ‘Viewing the 4D VQ PET scans of 20 patients on this clinical trial, we were able to accurately understand not only which areas of the lung inflate and deflate as normal, but which areas have healthy levels of blood perfusion (absorption of oxygenated air into the bloodstream).’
Dr Siva says, unexpectedly, some areas of lung that appeared to be well-aerated did not have any blood flow at all, and vice versa, meaning some sections of tissue were providing no functional benefit.
‘While we always work to minimise toxicity to non-cancerous cells in the delivery of radiation therapy, we can now see which sections of aerating and perfusing tissue are more important to the breathing capabilities of that patient, and make a more concerted effort to avoid them accordingly.’
Nuclear Medicine Physician and co-investigator, Associate Professor Michael Hofman, says there are many factors influencing lung tissue function that differ greatly between patients.
‘As well as the well-documented side-effects of smoking, factors that stop aerating lung tissue from perfusing include side-effects of cancer treatments and prescription medications, and even blood clots arising from deep vein thrombosis (DVT).’
Dr Siva says the trial was only possible through a world-leading collaboration between radiation oncologists and cancer imaging specialists at Peter Mac, one of  the first cancer centres in the world to incorporate PET imaging in clinical cancer care.
‘Now we know this imaging works, and have shown it is feasible to change our radiation therapy techniques to reduce toxicity to healthy, functioning parts of the lung, we hope to develop clinical trials of even more personalised treatment in the near future.’
Dr Siva’s study results are being presented today (Monday 28 October) at the International Association for the Study of Lung Cancer’s (IASLC) 15th World
Conference on Lung Cancer in Sydney