Lung Cancer Screening – Low Dose CT of Thorax

Enquiry & Booking: 8102 2022

‶Low-dose CT thorax is a screening tool which can reduce the mortality rate of lung cancer″

About CT Thorax

Computed tomography scan (CT scan) is a non-invasive imaging examination that combines X-rays with computer technology to create cross-sectional images of the body. Unlike conventional X-ray scan, which can only produce 2D images, CT scan uses a motorized X-ray source that rotates around the body to take series of x-rays images from different angles. The images are then sent to the computer to create slices, cross-sections or 360-degree images of a particular area of the body. Hence, CT scan can provide more detailed information than regular X-ray scan, particularly of internal organs, bones, soft tissues and blood vessels, and can also detect smaller abnormalities.

Conventional chest X-ray scan usually only takes view from the front and sometimes from the side. Structures shown are overlapped, for example, the ribs overlay the lung and the heart. If the abnormality(ies) is/are located in an area that is obscured by other structures, it is difficult for doctors to make a diagnosis. On the other hand, the cross-sectional images produced by CT thorax (CT scan of the chest) can avoid the problem of overlapping structures. It is also capable of detecting lung nodules as small as 3mm.

CT Scan

X Ray

What Is Low-Dose Computed Tomography (LDCT)?

As its name suggests, low-dose CT (LDCT) scan uses a lower dose of radiation to make detailed images of the body. The radiation dose our body absorbs depends on our size, weight and the part of the body that is targeted by the X-ray. Usually, the radiation dose of a regular CT scan is around 1.2-1.6mSv, and that of an LDCT scan is less than 0.5mSv.

Why Should I Get a Low-Dose CT Thorax?

Lung cancer usually shows no obvious symptoms in its early stages. When symptoms are observed, the disease has often developed into a more advanced stage. Early-stage lung cancer can be cured by surgical treatment, and the survival rate can reach up to more than 90%. Therefore, early diagnosis of lung cancer is of paramount importance. Low-dose CT thorax is proved in the medical field to be one of the screening tools that is effective in reducing the mortality rate of lung cancer.

Who Should Get a Low-Dose CT Thorax

People who are at high risk for lung cancer should get a regular scan. Risk factors for lung cancer include:

  • 50 years of age or older
  • Smoker
  • Former smoker with less than 15 years since quitting
  • Being exposed to randon (a naturally occurring radioactive gas that can cause lung cancer, commonly given off by soil and rock) for a long period of time
  • Cancer patients
  • With a family history of lung cancer
  • Patients with pulmonary fibrosis and chronic obstructive pulmonary disease(COPD)

According to the guidance given by the National Comprehensive Cancer Network (NCCN), there are two groups of people who are at high risk for lung cancer. Lung cancer screening is recommended for both groups.

Level of Risk Risks Factors
Group 1
  • 55-77 years of age
  • 30 or more pack years* of smoking and has quit within the past 14 years
  • Current smoker
Group 2
  • 50 years of age or older
  • 20 or more pack years* of smoking
  • Other risk factors (mentioned above)

*Pack years = number of packs per day x years of smoking
Ex: 1 pack per dady x 20 years of smoking = 20 pack years
      2 pack per day x 15 years of smoking = 30 pack years

The Procedure of Low-Dose CT Thorax
  • You should remove all metal objects such as jewellery and belt before the scan.
  • During the scan, you will be asked to lie on an examination table that will advance through a doughnut-shaped ring.
  • You will also be asked to hold your breath for around 5-10 seconds.

The scan is performed by a radiologic technologist and the entire process takes approximately 20-30 minutes. No fasting is required prior to the examination and no contrast dye is used.

Low-Dose CT Thorax Result and Follow-up

If the initial baseline LDCT scan results with no nodules, it is recommended to get a follow-up scan 12 months later. But if nodule(s) is/are found, your doctor will discuss the next step with you based on the size and characteristics of the nodule(s). A conventional chest CT scan, PET/CT scan or lung biopsy may be required to determine whether the nodule(s) is/are malign or not.

Read More

Pulmonary Nodules and Lung Cancer

FAQs (Frequently Asked Questions)

Q. Can chest X-ray replace low-dose CT thorax as a lung cancer screening tool?
A: No, it is because chest X-ray cannot detect smaller nodules. So far, no large-scale clinical studies have proven that screening with chest X-ray could help reduce the mortality rate of lung cancer.

Q: How should I choose between a conventional CT Thorax and a low-dose CT thorax?
A: Low-dose CT thorax is for people who are at high risk of lung cancer but with no obvious symptoms. The benefits of lung cancer screening with LDCT are that it involves a lower radiation risk, does not require contrast dye, and is more cost-efficient. Conventional CT thorax, on the other hand, is more for patients who have already been diagnosed with lung cancer or with noticeable symptoms. The scan can help to check for lung metastases and determine the stage of the cancer. It can also help doctors to diagnose other lung diseases, such as lung infection. For more information, please consult your doctor.

Q: Can I not quit smoking as long as I get screened regularly?
A: No. Smoking is the primary cause of lung cancer, accounting for 80% of cancer cases. A regular low-dose CT thorax can reduce the rate of mortality, but cannot prevent the disease from happening.

Related Specialty Services

Virtus Respiratory Medicine

Enquiry & Booking: 8102 2022

Remarks :

1.  Advanced booking is required for this service.
2.  Lung Cancer Screening service location :
  Virtus Medical Tower - 17/F, Virtus Medical Tower, 122 Queen's Road Central, Hong Kong.
  Virtus Medical Centre - 11/F, H Zentre, 15 Middle Road, Tsim Sha Tsui, Kowloon.
3.  Medication and other treatment/investigation cost are not included in this programme.
4.  Virtus Medical reserves the right to amend any of the above terms and conditions without prior notice. In case of any dispute, Virtus Medical will reserve the right of final decision.

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+852 8102 2022
17/F, Virtus Medical Tower, 122 Queen's Road Central, Hong Kong
11/F, H Zentre, 15 Middle Road, Tsim Sha Tsui, Kowloon