Breast Imaging- DM, US, and MRI

As pixe size decreases, the amount of data contained in the images will:

1. Increase

2. Remain the same

3. Decrease

4. Pixel size has no effect on image data

1

The data contained in the images will increase, but the image noise will also increase.

In digital imaging, the dynamic range refers to:

1. Range of intensities that are displayed

2. Random background information that is detected but does not contribute to image quality

3. Range of value over which a system can respond

4. Layout of the cells in rows and columns

3

The range of values over which a system can respond.

It is also known as the gray scale or the number of shades of gray that can be represented in each pixel.

The detector system in digital mammography is categorized as direct if:

1. The x-rays are absorbed by the detector and an electrical signal is created in one step

2. The x-rays are absorbed and converted to light, which is then detected by TFD

3. The system has a wide dynamic range

4. The spatial frequency is high

1

The detector systems are direct or indirect. The direct system creates the electrical signal in one step, whereas the indirect system uses a two-step process similar to screen/film systems. The dynamic range refers to the range of values over which a system can respond, and the spatial frequency is the measure of the line pairs per centimeter.

During the reading process, the light emitted from the PSP is collected by

1. TFT

2. CCD

3. ADC

4. PMT

4

During the reading process, light that is emitted from the photostimulable storage phosphor (PSP) is collected by a light guide and sent to a photomultiplier tube (PMT), photodetector (PD), or charge-coupled device (CCD). The PMT detects the blue light given off by the trapped electrons as they return to their normal neutral state. Signal from the PMT is sent to an analog-to-digital converter (ADC) and then to a computer for displays.

The resultant digital information can now be electronically trans-mitted, manipulated, and more efficiently stored.

Most of the risks of MRI of the breast are associated with:

1. The magnetic properties of the patient

2. Ferromagnetic metals

3. Technologist errors

4. Radiologist error

1

During an MRI examination, the patient is placed within a powerful magnet. Any metal objects on or around the patient can be a danger because they will be drawn to the magnet.

What is the name of the scintillator used in the flat-panel technology?

1. Amorphous silicon

2. Cesium iodide

3. Amorphous selenium

4. Thin-film transistor

2

Indirect digital systems use a two-step process. A scin-tillator, such as cesium iodide (CsI) doped with thallium (TI), absorbs the x-rays and generates a light scintillation that is then detected by an array of the thin-film transistor (TFT) or thin-film diode (TFD). Amorphous silicon and amorphous selenium are photoconductors used to collect electrons in the TFT.

In MRI of the breast, a large value for the T1 or T2 will indicate:

1. A long, gradual relaxation time

2. A rapid relaxation time

3. Hydrogen atoms are not aligned to the external magnetic field

4. The RF field was not applied

1

The MR image is a record in the difference in radio-frequency signals from different body tissues. A large value for T1 or T2 indicates a long, gradual relaxation time, whereas a small value indicates a rapid relaxation time.

Sound waves cannot travel through:

1. A medium

2. Vacuum

3. Gasses

4. Liquids

2

Sound is a mechanical longitudinal wave that cannot travel through vacuum. It needs a medium for travel. Sound also travels very poorly through gasses.

Typically, a lesion with no internal echoes, no spiculations, and fewer than four gentle lobula-tions would represent what type of lesion on ultrasound?

1. Malignant

2. Intermediate

3. Carcinoma

4. Benign

4

These are the characteristics of a benign lesion.

Malignant lesions tend to be irregular and spiculated margins.

Intermediate lesions are harder to define, but they tend to have an echogenicity similar to fat.

The ultrasound transducer is used to:

1. Convert electric energy to acoustic pulses

2. Convert acoustic pulses to electric energy

3. Change the speed of the sound waves

1. 1 and 2 only

2. 2 and 3 only

3. 1 and 3 only

4. 1,2, and 3

1

The transducer consists of crystal made up of piezoelectric material capable of converting electrical energy into acoustic energy on transmission and acoustic energy into electrical energy on reception.