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Biophysics MCQ

By AdminPosted On 05-Oct-2016

1. Color Doppler : Biophysics MCQ


How can the blue colored flow pattern be described?


a) Deoxygenated blood flow

b) Flow away from the color box

c) Flow towards the color box

d) Low volume of flow per unit area

e) Venous flow pattern


Correct Answer: b) Flow away from the color box. The color only describes the flow of the fluid towards (red) or away (blue) from the color box. It does not correlate to venous or arterial flow.


2. Polyglactin Suture : Biophysics MCQ


Polyglactin sutures are used extensively in surgical procedures, particularly to ligate vessels. What are the key features of polyglactin sutures?


a) Braided, absorbable and synthetic

b) Braided, non-absorbable and synthetic

c) Non-braided, absorbable and natural

d) Non-braided, absorbable and synthetic

e) Non-braided, non-absorbable and natural


Correct Answer: a) Braided, absorbable and synthetic. Polyglactin sutures are used to ligate pedicles and close the uterus during a caesarean section. To achieve this, the sutures are braided to prevent the knots from slipping.


3. Formaldehyde gas sterilization is employed for : Biophysics MCQ


a) Sterilizing heart lung machines

b) Glass materials

c) Paper and cloth

d) Fumigation of operation theater and ICUs


Correct Answer: d) Fumigation of operation theater and ICUs

Fumigation with formaldehyde vapor is the recognized and most commonly used method because of its cost effective procedure. It has a much longer shelf life if some methanol is added to inhibit polymerization to paraformaldehyde, but is much more volatile. Glutaraldehyde has a short shelf life (

4. Cautery Burn : Biophysics MCQ


At the end of surgery you notice an area of burn near the attached diathermy plate. The diathermy plate seems to be partially detached. Which of the following would be the most likely aetiology?


a) Due to the plate not being secured properly, the current density was concentrated in the smaller area where the plate was attached

b) High voltage was used

c) The injury may have resulted from insulation failure

d) The power output was accidentally turned up

e) The surgeon may have accidently touched the instrument to the patient’s thigh


Correct Answer: a) Plate not being secured properly. The amount of thermal damage is dependent upon the current density and the size of the current. The current density in the tip of the needle will be very high as the current is concentrated in the small point. The plate used for the return electrode in monopolar diathermy has a larger surface area of contact, resulting in a much lower current density. Any thermal effect is therefore widely dissipated. This highlights the need for the whole surface of the plate to be securely attached to the body.


5. Laser in Gynecology : Biophysics MCQ


Which laser can be used in gynaecological surgery, is invisible without an aim beam and cannot be transmitted down a fibre optic cable?


a) Argon

b) Carbon dioxide

c) Helium–neon

d) Neodymium:YAG

e) Potassium titanyl phosphate


Correct Answer: b) Carbon dioxide. The CO2 laser generates an invisible light and requires an aiming beam, usually helium–neon. It cannot be transmitted down a fibre optic cable and is absorbed by water. It is used in cervical treatment but is limited by the fact that it does not work in the presence of blood.


6. TVS : Biophysics MCQ


What is the frequency of a transvaginal ultrasound scan?


a) 2 MHz

b) 6 MHz

c) 18 MHz

d) 23 MHz

e) 32 MHz


Correct Answer: b) 6 MHz. The higher the frequency the greater the axial resolution of ultrasound meaning you can distinguish between structures based on their distance from the ultrasound beam). Unfortunately, increasing the frequency reduces the penetration of the beam. Transabdominal ultrasound therefore requires a lower frequency and has a lower resolution. Lateral resolution (distinguishing two structures that are the same distance away from the ultrasound beam but are side by side) is not improved by increasing the frequency and can only be increased by improving the focus of the beam.


7. Unipolar Cautery : Biophysics MCQ


In monopolar diathermy which feature prevents electrocution occurring?


a) Direct current (DC) not alternative current (AC)

b) High frequency

c) Low current

d) Low voltage

e) The patient is earthed


Correct Answer: b) High frequency. The high frequency prevents depolarisation of the cell. The voltage and current would certainly be enough for electrocution to occur.


8. Electrosurgery : Biophysics MCQ


What would be the frequency of the electric current used in electrosurgery?


a) 35 Hz

b) 50 Hz

c) 100 Hz

d) 500 Hz

e) 10 000 Hz

Correct Answer: d) 500 Hz. When an electric current of 50 Hz (household frequency) passes through the body it causes an irreversible depolarisation of the cell membrane. It may also cause depolarisation of cardiac muscles, resulting into death. If the current frequency is increased above 200 Hz depolarisation does not occur. Instead ions are excited to produce thermal effect. A frequency of 100 Hz may cause neuromuscular stimulation. The AM radio band utilises the frequency of 10,000 Hz.


9. Cutting and Coagulation : Biophysics MCQ


You wish to achieve a cutting and simultaneous coagulation effect from the diathermy machine. How is this best achieved?


a) Use bipolar diathermy with blended waveform

b) Use bipolar diathermy with yellow (cutting pedal)

c) Use fulguration

d) Use monopolar diathermy with blended waveform

e) Use monopolar diathermy with yellow (cutting) and blue (coagulation) pedal simultaneously

Correct Answer: d) Use monopolar diathermy with blended waveform. Bipolar can only coagulate; it cannot cut and coagulate effectively.


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