Question

True or false:

1- X ray travels in a straight line

2- Negatively charged particle of an atom is electron

3- In mri modality, the time defined by T1 increase with magnetic field

4- In mri device, increasing the magnetic field can produce more susceptibility artifacts

5- If we don’t apply external magnetic field to the human body, water molecules spin randomly

6- We can align the water molecules spinning behavior if we apply an external magnetic field to the body

7- The magnetic field, produced by a single photon is stronger than the static magnetic field, produced by main magnet in MR devices

8- The spatial information of image slices are determined by 3 gradient fields

9- We can obtain many slices by using mri modality on coronal plane

10- Photons spin at Larmour frequency during collection of mri slices

11- Radio-frequency (RF) waves have shorter wavelength than x-rays

12- We can obtain mri slices from a patient having a pacemaker

Fill in the blanks:

We can observe precession at particular frequency which is equal multiplication of _______ by ______ about the vertical axis.

Answer 1

1- X ray travels in a straight line - TRUE

X-rays travel in straight lines and a beam of X-rays diverges from its source.

2- Negatively charged particle of an atom is electron - TRUE

The electron is a subatomic particle, with a negative elementary electric charge. Charge on an electron is - 1.602*10^-19 C.

3- In mri modality, the time defined by T1 increase with magnetic field - TRUE

T1 will increase as field strength increases. For most biological tissues, empirical measurements suggest that T1 increases approximately as B_o^1/3.

4- In mri device, increasing the magnetic field can produce more susceptibility artifacts - FALSE

Susceptibility artifacts are worse at high fields.

5- If we don’t apply external magnetic field to the human body, water molecules spin randomly - TRUE

The human body mostly composed of water molecules which have an abundance of water molecules (protons). Ecah proton has its own small magnetic field and in body protons spin randomly.

6- We can align the water molecules spinning behavior if we apply an external magnetic field to the body - TRUE

When external magnetic field is applied to the body, all the protons allign themselves with the external magnetic field.