Author
Bowtie Team
Updated on
2025-08-12
Disclaimer: This article is translated with the assistance of AI.
Lung cancer tops the charts as the deadliest cancer, but early detection can dramatically cut mortality rates through timely treatment. Discover how Low-Dose Computed Tomography (LDCT) outperforms traditional CT scans in spotting lung cancer early—Bowtie’s info team breaks it down for you in this essential guide.
What is LDCT Scan (Low-Dose CT)?
Low-Dose Computed Tomography Thorax (LDCT) is a medical imaging technique with lower radiation levels. It uses X-rays to penetrate the body, then processes the images via computer. Compared to traditional X-ray , it provides multi-angle and clearer views of internal tissues or organs, capturing cross-sectional or 3D images mainly for diagnosing lung diseases.
Even if organs overlap in frontal views, thoracic CT scans can use cross-sections to avoid overlaps, clearly detecting tiny abnormalities in the body and boosting diagnostic accuracy.
Diseases Diagnosed by LDCT Scan
Early lung cancer symptoms are often subtle or absent, so it’s usually detected at late stages—earning it the nickname “silent killer.”
LDCT not only has low radiation but can clearly spot tiny abnormalities , allowing accurate early lung cancer diagnosis and improving recovery chances.
How Reliable is LDCT for Lung Cancer?
LDCT is highly reliable, with a sensitivity* of 93.8% and specificity** of 73.4%. It detects tiny lung changes and clearly shows nodules as small as 5mm. Radiologists assess features like size and density to determine if they’re benign or malignant, diagnosing early lung cancer.
Studies show high-risk groups getting annual LDCT scans can reduce lung cancer mortality by 26% in men and 61% in women .
Another perk: its radiation is much lower than X-rays or standard lung CT scans.
- * Sensitivity measures if the test correctly identifies those with the disease.
- ** Specificity measures if the test gives negative results for those without the disease.
Who Should Get an LDCT Scan?
To lower lung cancer risk, we recommend asymptomatic high-risk individuals get an LDCT scan. High-risk groups include:
- People aged 50 and above
- Long-term smokers
- Former long-term smokers who quit less than 15 years ago
- Those with long-term exposure to carcinogens like radon
- Individuals with a personal history of cancer
- Family history of lung cancer
- Patients with pulmonary fibrosis or COPD
Plus, a US study suggests the following high-risk individuals get LDCT scans at least annually :
- Smoking index^ (pack-years) over 20
- Aged 50 to 80
- Current smokers or quit less than 15 years ago
- ^ Smoking index = number of cigarettes smoked per day (packs) x years of smoking
LDCT and Lung CT Scan Differences
Most people are unfamiliar with low-dose computed tomography (LDCT) scans. The table below outlines the differences between LDCT and traditional lung CT scan :
| Low-Dose Computed Tomography | Traditional Lung CT Scan | |
| Radiation Dose | Lower | Higher |
| Contrast Agent Injection | Not required | Required |
| Cost | Cheaper | More expensive |
| Suitable For | High-risk individuals for lung cancer without symptoms | Individuals diagnosed with lung cancer or showing symptoms |
LDCT Scan Procedure and Steps
A low-dose computed tomography scan is a simple, quick, painless, and non-invasive medical procedure that typically takes just a few minutes . The steps are as follows:
- Lie flat on a bed connected to the scanning machine
- Be moved into the scanner tube
- Follow instructions to take a deep breath and hold it for about 5 to 10 seconds
Things to note before the scan:
- Remove any metal items like jewelry or belts before the LDCT scan
- No need to fast, as contrast agent injection is not required
Things to note after the scan:
- You can resume normal activities and diet without any restrictions
- Follow-up LDCT plans depend on the scan results. If no nodules are found in the baseline scan, a follow-up can be done in 12 months
- If nodules are detected in the initial LDCT, the doctor will recommend next steps based on their size and type. This may include a chest CT scan, PET scan , or lung biopsy to determine if they are cancerous
LDCT Scan Costs in HK
| Hospital / Clinic / Medical Centre | LDCT Scan Fee |
| Hong Kong Baptist Hospital | HK$1,835 |
| CUHK Medical Centre | HK$2,370 |
| Precious Blood Hospital | HK$1,900 |
| St. Teresa’s Hospital | HK$1,800 |
| Virtus Medical | HK$1,800 |
| Trinity Medical Centre | HK$1,700 |
| Human Health | HK$2,880 (including lung function test) |
LDCT Lung Screening FAQs
1. Could LDCT scans lead to false positives?
Sure, while low-dose CT screening can significantly lower mortality rates for high-risk lung cancer groups, its super high sensitivity often results in “false positives.” This might lead to unnecessary invasive follow-up tests.
That’s why experts recommend LDCT only for those at high risk of lung cancer. Plus, the doctors performing the scan and reading the reports should have plenty of experience to keep things accurate.
2. Are there risks with LDCT scans?
LDCT scan risks are tied to its extremely high sensitivity.
Because of this sensitivity, it’s easy to get “false positives” or even “overdiagnosis,” which can cause unnecessary worry and stress for patients. They might end up undergoing invasive tests that aren’t really needed.
On top of that, to double-check for any issues, patients could face repeated or frequent LDCT scans, ramping up radiation exposure and potentially harming their health.
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