Lung cancer is the deadliest form of cancer in Canada, representing the highest percentage of estimated new cases (13.5%) and estimated deaths from all cancer cases (26.8%) in 2015. To combat this, the Canadian Task Force on Preventative Health Care has recommended low-dose computed tomography (LDCT) screening on high-risk patients for lung cancer in Canada. The reasoning is that if cancerous tumors are detected at an earlier stage, it costs less to treat the cancer, and the patient has a much higher probability of survival.  

However it is not so simple! LDCT screening results in a large number (up to 90%) of false positive cases: Suspicious nodules that turns out not to be malignant (deadly) cancer. Currently, when a suspicious nodule is detected, to determine if the nodule requires treatment the patient may undergo further imaging: CT, nuclear imaging, or MRI; or a biopsy procedure. The risks associated with this diagnostic follow up are small for the imaging, however on a “high-risk” patient, the lung is a fragile organ on which to operate on, pneumothorax (lung collapse), hemorrhage (bleeding), or death may occur. 

Our project looks to improve CT technology in order that, upon finding a suspicious nodule, an ultra-high resolution scan may be performed to accurately diagnose the nodule’s malignancy – without having to resort to invasive biopsy procedures! The first step in our investigation is to prove that CT can distinguish between malignant and benign (harmless) cancerous subtypes. We are examining images of various lung tissues (malignant, benign, normal, and non-cancerous lung conditions) under a micro-CT to elucidate features that would allow a pathological diagnosis. Our team consists of pathologists, radiologists, oncologists, medical physicists, and more! We hope to be able to use radiomics: an emerging science of garnering information, including phenotype, from imaging characteristics, in our diagnostic methodology. 

If we are able to prove that CT technology is able to diagnose these suspicious nodules detected on a LDCT, we will also be able to determine what resolution (ability to distinguish small features) is required to perform this diagnosis. Essentially, a better resolution means that more ionizing radiation is delivered to the patient. We must be able to accurately perform a diagnosis, but also want to minimize the radiation delivered as this radiation has an (albeit small) risk of causing future cancer. Remember, we want this diagnostic technique to not only be safer than current techniques, e.g. biopsy, but also to be as safe as possible

We expect that if we are able to prove that this diagnosis is possible using CT, the use of improved technology for diagnostic CT will allow us to achieve our desired resolution. Newer technologies such as improved resolution detectors, variable resolution CT, carbon nanotubes, flying focal spots, liquid-metal-jet anodes, volume-of-interest filtration, and more, have already been developed to improve resolution, and decrease scanning time on a CT. This will allow these ultra-high resolution CT methods to be employed along with a LDCT to make early detection of lung cancer less costly and safer! 

 

For more information on LDCT screening: 

http://canadiantaskforce.ca/ctfphc-guidelines/2015-lung-cancer/harms-and-benefits/