Radiology Education: X-ray and CT Scan

This site covers the two imaging exams used most often in medicine: X-ray and CT scan. Each topic is explained in plain language, from how the equipment works and its clinical uses, to patient preparation and how to read a report.

There are 40 interlinked pages. You can start with the basics, browse by category, or look up a specific exam. Each page links to related topics, and you can switch to the Indonesian version using the link in the top right corner.

What are X-rays and CT scans?

X-ray and CT scans are two medical imaging exams that use ionizing radiation to see inside the body without surgery. Both are very common in hospitals and clinics, and they are used to diagnose conditions, monitor treatment, and plan procedures.

An X-ray produces two-dimensional images quickly, so it is often the first exam for fractures, pneumonia, or bowel obstruction. A CT scan creates a series of cross-sectional views with much more detail, and is often requested for stroke, serious injury, or tumor evaluation.

How to choose between X-ray and CT

The choice of exam depends on symptoms, the suspected organ, and the clinical question to be answered. No single exam is always best. An X-ray is often sufficient for simpler conditions, while a CT is chosen when additional detail is truly needed.

Doctors also consider radiation dose, equipment availability, patient conditions such as pregnancy or contrast allergy, and whether a radiation-free alternative such as ultrasound or MRI is suitable. An open discussion with your doctor is the best way to understand why a particular exam was chosen.

Safety and radiation dose

Ionizing radiation can damage cells at high doses, so exposure is always limited using the ALARA principle: as low as reasonably achievable. A chest X-ray delivers a very low dose, while CT delivers higher doses, especially in the abdomen and pelvis.

The risk from a single diagnostic exam is generally small compared with its diagnostic benefit. Even so, repeated exams should be discussed with a doctor, and children and pregnant patients require special attention.

How to use this site

This site has 40 interlinked pages divided into three categories: X-ray, CT scan, and general. Each page includes a summary, sections explaining the topic, key points, and links to related pages.

New readers are encouraged to begin with the six pages in the Start here section, then explore categories that match their interests. You can switch to the Indonesian version using the link in the top right corner of each page.

Preparing for an exam

General preparation includes telling staff about possible pregnancy, allergies, previous imaging, and any metal implants or medical devices in your body. Remove jewelry and metal objects in the area being examined, and wear comfortable clothing.

For a CT with contrast, fasting for a few hours is often requested, and doctors need to know about kidney disease or diabetes if you take metformin. Always follow the instructions from the facility where you are examined, because protocols can differ.

Reading your results

Results are written by a radiologist in a report that includes findings and an impression. The impression is the most important summary. Phrases such as 'no abnormality seen' or 'suspected' should be read in the context of your symptoms.

Do not draw diagnostic conclusions on your own from reading a report. Write down questions and discuss them with the doctor who ordered the exam, since clinical assessment remains the basis of medical decisions.

When to seek help right away

If you have a serious injury, sudden chest pain or shortness of breath, weakness of one side of the face or body, or loss of consciousness, contact the nearest emergency service immediately. Do not wait for imaging results before seeking help.

For ongoing concerns that are not urgent, consult a doctor before arranging exams on your own. This site is not intended to replace medical consultation.

Start here

If you are new to radiology, these six pages are a good place to begin.

Frequently asked questions

Are X-rays or CT scans dangerous?

Both use ionizing radiation. An X-ray dose is usually small, while a CT dose is higher. Doctors weigh the diagnostic benefit against the risk before recommending an exam.

Do I need to fast?

It depends on the type of exam and whether contrast is used. Follow the instructions from the facility where you are being examined.

Why does my result show no abnormality yet?

Not every abnormality shows up on a single exam. Discuss results with the doctor who ordered the exam, since follow-up imaging is sometimes needed.

Important note

The information on this site is general and does not replace diagnosis, advice, or treatment from a healthcare professional. If you have symptoms, consult a doctor.