Noise increases with an increase in:

Noise increases with an increase in:

• A. mAs
• B. Speed class
• C. SID
• D. OID

Answer: (B)

Noise in radiographic images is quantum noise, caused by the random arrival of x-ray photons at the image receptor. The stronger the signal (more photons reaching the receptor), the less noticeable the noise; fewer photons mean more pronounced noise. When you use a faster speed class, the receptor becomes more sensitive, so you achieve the same image density with less exposure. If you keep the exposure level fixed, switching to a faster speed class reduces the number of photons contributing to the image, which increases quantum noise. That’s why increasing speed class leads to higher noise unless you compensatingly raise exposure (mAs or other factors) to restore photon fluence.

Noise in radiographic images is quantum noise, caused by the random arrival of x-ray photons at the image receptor. The stronger the signal (more photons reaching the receptor), the less noticeable the noise; fewer photons mean more pronounced noise.

When you use a faster speed class, the receptor becomes more sensitive, so you achieve the same image density with less exposure. If you keep the exposure level fixed, switching to a faster speed class reduces the number of photons contributing to the image, which increases quantum noise. That’s why increasing speed class leads to higher noise unless you compensatingly raise exposure (mAs or other factors) to restore photon fluence.