Basic knowledge of medical imaging over the years (64)-Tianjin medical and health in 2020

Basic knowledge of medical imaging over the years (64)-Tianjin medical and health in 2020

1. The following statement about collimator is wrong:

A. The function of the front collimator is to control the width of the X-ray beam in the direction parallel to the long axis of the human body, so as to control the thickness of the scanning layer.

B the front collimator can reduce the interference of scattered light from the direction outside the imaging plane.

C.x-ray tube side collimator, also called front collimator.

D detector side collimator, also called back collimator.

E the collimator can reduce the radiation dose on the patient's body surface.

2. The following statements about the baseline of brain CT scanning are wrong:

A. The auditory orbital line is the connecting line between the inferior orbital margin and the ipsilateral external ear foramen.

B The auditory canthus line is the connecting line between the right (left) ear hole and the right (left) lateral canthus, which is often used for head CT scanning.

C the eyebrow line is the connecting line between the midpoint of the upper edge of the eyebrow and the ipsilateral external auditory canal.

D, the section of the auditory canthus line passes through the eye socket, the middle cranial fossa and the upper part of the posterior cranial fossa.

E. Auditory eyebrow line shows the fourth ventricle and basal ganglia well.

3. The statement about brain and throat CT photography is correct:

A. When skull lesions or intracranial lesions invade the skull, there is no need to add bone window.

B. The skull window has a width of 300~ 1000HU and a window position of 30~50HU.

C window position photography of brain soft tissue: window width 1200~ 1500HU, window position 35~45HU.

D. When scanning the larynx, the examinee can be instructed to send the letter E continuously, so that the vocal cords are adducted and the piriform fossa is enlarged.

E. The scanning slice thickness of throat is 10mm, and the small lesion can be 2 ~ 3 mm, and the reconstruction interval is the same as the slice thickness.

4. The following statement about CT image post-processing is wrong:

A.MPR is a two-dimensional image post-processing technology.

Surface reconstruction (cardiopulmonary resuscitation) is a two-dimensional image post-processing technology.

Surface masking technology (SSD) is a two-dimensional image post-processing technology.

Three-dimensional maximum density projection (MIP) is a post-processing technology for three-dimensional images.

E. Surface Covering Technology (SSD) is a post-processing technology of 3D images.

5. The following factors affecting X-ray production are described incorrectly:

A continuous x-ray intensity is directly proportional to the atomic number of the target substance.

B The higher the atomic number of the anode target substance, the smaller the X-ray intensity.

The tube current does not affect the quality of X-ray.

D. The greater the tube current, the more electrons impact the anode target surface, and the greater the X-ray intensity.

The maximum energy of electrons depends on the peak value of tube voltage.

6. Which of the following is not a physical feature of X-rays?

A. Infiltration

B. fluorescence

C. thermal action

D. ionization

E. coloring

Reference answer and analysis

1. Reference answer B. Analysis: There are two kinds of collimators, one is the X-ray tube side collimator, also called the front collimator. Its function is to control the width of X-ray beam in the direction parallel to the long axis of human body, so as to control the thickness of scanning layer. The other is the detector side collimator, also called back collimator. Its slits are aimed at a detector respectively, so that the detector only receives the light vertically incident on the detector and minimizes the interference of scattered light from the direction outside the imaging plane. Therefore, choose B in this question.

2. Reference answer D. Analysis: The auditory orbital line is the connecting line between the inferior orbital margin and the ipsilateral external auditory meatus. With this line, the cross section passes through the eye socket, the middle cranial fossa and the upper part of the posterior cranial fossa. The auditory canthus line is the connecting line between the right (left) ear hole and the right (left) lateral canthus. This line is often used as the scanning baseline for head CT scanning. The auditory eyebrow line is the connecting line between the midpoint of the upper eyebrow margin and the ipsilateral external auditory meatus. The image of this line scan is beneficial to display the tissue structure of the fourth ventricle and basal ganglia, and the scanning range is comprehensive after passing through the lowest points of the three cranial fossa. Therefore, choose D in this question.

3. Reference answer D. Analysis: Brain window photography is often used for brain CT images. Lesions of skull base and internal auditory canal; Craniocerebral trauma; Skull lesions or intracranial lesions invade the skull, and a bone window must be added. Bone window width 1000~ 1400HU, window position 300~500HU. For scalp soft tissue lesions, use soft tissue window. Soft tissue window photography: the window width is 300~400HU and the window position is 35~45HU. The thickness of throat scanning layer is 5mm, not 10 mm, so D is selected in this question.

4. Reference answer C. Analysis: Two-dimensional post-processing technology includes multiplanar reconstruction (MPR) and curved surface reconstruction (cardiopulmonary resuscitation). Surface shadow technology (SSD), maximum density projection (MIP), minimum density projection (MinIP), virtual endoscopy technology (CTVE) and volume imaging (VR) all belong to three-dimensional post-processing technology. Therefore, this question chooses C.

5. Reference answer B. Factors affecting the generation of continuous X-rays: (1) Target substance: The intensity of continuous X-rays is directly proportional to the atomic number of the target substance. Under the same tube voltage and tube current, the higher the atomic number of the anode target substance, the greater the X-ray intensity. (2) Tube current: The tube current does not affect the quality of X-rays, but the intensity of X-rays depends on the tube current at a certain tube voltage. The greater the tube current, the more electrons hit the anode target surface, and the greater the X-ray intensity. (3) Tube voltage: The maximum photon energy in the X-ray beam is equal to the kinetic energy of high-speed electrons colliding with the target substance, and the maximum electron energy depends on the peak value of the tube voltage, so changing the tube voltage changes the maximum photon energy, and the shape of the whole X-ray spectrum also changes. (4) High voltage waveform.

6. Reference answer E. Analysis: X-ray feature classification: 1. Physical characteristics: invisible, uncharged, penetrating, fluorescent, ionizing, thermal 2. Chemical characteristics: photosensitivity, coloring 3. Characteristics of biological effects.