📌 [Part 1] The Hidden Truth behind How Medical Imaging Devices
📌 [Part 1] The Hidden Truth behind How Medical Imaging Devices — The Eyes of Modern Medicine
Table of Contents
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Introduction: Multiple lenses that illuminate the body
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X‑ray and CT — The quantum mechanics of light passing through the body
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Ultrasound — A landscape drawn by the time of waves
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MRI — Awakening atomic spins with magnetic fields
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Radiation safety (brief comparison)
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Conclusion and preview of the next installment
Introduction: Multiple lenses that illuminate the body
Our bodies are full of invisible signals and changes. Modern medicine “shows” that interior through various imaging devices. In this article, I will examine how commonly encountered hospital tools — X‑ray, CT, ultrasound, and MRI — operate, and also explore the physical meaning behind those operating principles.
X‑ray and CT — The quantum mechanics of light passing through the body
Basic principle
X‑ray is a high‑energy electromagnetic wave — in effect, a photon with substantial energy. These photons interact with the atoms (and their surrounding electrons) that make up the human body as they pass through.
High‑density tissues (for example, bone) absorb or scatter photons more, while low‑density tissues (muscle, fat, air) allow photons to pass relatively easily. As a result, a 2‑dimensional image is produced on film or a digital detector showing contrasts of light and dark according to density differences.
A brief quantum‑mechanical perspective
The interactions between X‑ray photons and matter are ultimately the sum of microscopic (quantum) events. Processes such as photon absorption by electrons (photoelectric effect) or energy‑sharing and scattering are described by quantum mechanics. The whites and blacks we see in an image are the macroscopic outcome of those microscopic interactions.
CT reconstruction
CT (Computed Tomography) collects many X‑ray cross‑sectional images from multiple angles, and a computer uses mathematical algorithms to reconstruct three‑dimensional information. It interprets the sum of quantum signals (photon absorption and scattering) from different directions to produce cross‑sectional images.
Ultrasound — A landscape painted by the time of waves
Basic principle
Ultrasound uses high‑frequency sound waves that humans cannot hear, not ionizing radiation. A transducer sends ultrasonic pulses; echoes reflected from tissues return and their time delays are measured to calculate distances and form an image.
A relativistic perspective
Ultrasound imaging reconstructs distances based on differences in time (round‑trip time). Also, the same structure can appear differently depending on the transducer’s position, angle, pressure, and the medium (water, fat, air, etc.).
Advantages & limitations
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Advantages: No radiation; real‑time observation possible (fetal monitoring, blood flow, organ motion, etc.).
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Limitations: Operator skill influences quality; structures behind air or bone are difficult to visualize.
MRI — Quantum resonance that awakens atomic spins with magnetic fields
Basic principle
MRI (Magnetic Resonance Imaging) uses the spin property of hydrogen nuclei (protons) in the body. Under a strong static magnetic field, these spins align; when a specific radiofrequency (RF) pulse is applied, the spins are excited. When the RF is turned off, the spins return to their original state and emit tiny signals that MRI detects to form an image.
Quantum‑mechanical perspective
MRI directly exploits the quantum properties (spin and resonance) of nuclei. By converting slight differences in Larmor frequency and relaxation characteristics into image signals, MRI visualizes fine differences in soft tissues. That is why it provides very detailed images of the brain, spine, and joints.
Features
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No ionizing radiation.
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Long scan times and relatively high cost.
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Scans are performed inside a closed bore, which may be uncomfortable for some patients.
Radiation safety (brief comparison)
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Chest X‑ray: ~0.1 mSv
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Abdominal CT: ~10 mSv
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Reference: Natural background radiation exposure is approximately 2 mSv per year (approximate).
Conclusion and preview of the next installment
In the next installment, I will examine how these devices are chosen and used for actual diseases, and how they can be harmonized with Traditional Asian Medicine’s holistic diagnostic approach.
This was a brief review intended to help patients better understand the principles and diagnostics of commonly known imaging methods.
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