MCQ ----X-ray tubes of CT scan

543.True regarding X-ray tubes of CT scanner

a.anode-cathode axis parallel to the axis of rotation of the scanner to minimize heel effect

b.typically have two focal spots ,the smallest being about 0.6mm

c.heat capacities of 4MJ or more

d.incorporation of heat exchanger to cool oil

e.typically scanners are operated at 120 kv

ANS OF PREVIOUS BLOG

506.True regarding digital radiography .

a. Detective quantum efficiency (DOE) reflects the efficiency of phosphor detection and noise added to the detector signal

b.DQE may be 100% in DR system

c.DQE of CR system and film-screen system is close to 30%

d.Disadvantage of DR in comparison to CR are cost and versatility

e.a DR system  have the same flexibility in positioning as a CR plate

506.acd-- Detective quantum efficiency (DOE) reflects the efficiency of phosphor detection and noise added to the detector signal. DQE for  DR system may be as high as 65%.DQE  are lower than 100% because of less than 100% absorption of X-rays in the device and internal sources of noise.(Chapter 5, page no.87,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON DIGITAL RADIOGRAPHY

506.True regarding digital radiography 

a. Detective quantum efficiency (DOE) reflects the efficiency of phosphor detection and noise added to the detector signal

b.DQE may be 100% in DR system

c.DQE of CR system and film-screen system is close to 30%

d.Disadvantage of DR in comparison to CR are cost and versatility

e.a DR system  have the same flexibility in positioning as a CR plate

ANS OF PREVIOUS BLOG

501.True regarding amorphous silicon thin-film transistor (TFT) arrays

a.TFT is essentially a large integrated circuit

b.the dimensions of array correspond to the size of the area to be imaged

c.a transistor is a device that minimize an electrical signal

d. in TFT, the amplified signal is stored as an electrical charge

e.The charge can be released by a high potential and is applied column by column

501.abd------True regarding amorphous silicon thin-film transistor (TFT) arrays transistor is a device that amplifies  an electrical signal  and in TFT, the amplified signal is stored as an electrical charge.The charge can be released by a high potential and is applied row by row,so that timing of the detected signal determines the position of the pixel from which it originated. (Chapter 5, page no.86,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON DIGITAL RADIOGRAPHY

501.True regarding amorphous silicon thin-film transistor (TFT) arrays

a.TFT is essentially a large integrated circuit

b.the dimensions of array correspond to the size of the area to be imaged

c.a transistor is a device that minimize an electrical signal

d. in TFT, the amplified signal is stored as an electrical charge

e.The charge can be released by a high potential and is applied column by column

ANS OF PREVIOUS BLOG

493.True regarding CR reader.

a.plate is removed from cassette in reader and scanned by laser

b.optical fibre above the plate  is used for scanning

c.rotating mirror above the plate direct emitted light to photomultiplier tubes

d.single scanning is enough to extract information

e.exposure of plate to light done to erase the residual signal

493.ae-----In CR reader, plate is removed from cassette in reader and scanned by laser .Rotating mirror  is used for scanning.Optical fibres  above the plate, direct emitted light to photomultiplier tubes.Repeated scanning is done  to extract information. .(Chapter 5, page no.84,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ on Computed radiography reader.

493.True regarding Computed radiography reader.

a.plate is removed from cassette in reader and scanned by laser

b.optical fibre above the plate  is used for scanning

c.rotating mirror above the plate direct emitted light to photomultiplier tubes

d.single scanning is enough to extract information

e.exposure of plate to light done to erase the residual signal



ANS OF PREVIOUS BLOG

473.True regarding mammography. 

a.aims to show microcacifications that may be 100micrometer or less

b.show tissues having much lower intrinsic contrast

c.atomic number of glandular tissues and adipose tissue (approx 7.4 and 6.5 respectively)

d.use of a broad bremsstrahlung spectrum  for imaging

e.target materials used for mammography  are tungsten ,molybdenum(z=42) and rhodium(z=45)

473.abc---- In mammography, use of a broad bremsstrahlung spectrum from a tungsten target is far from ideal and now it is standard practice to make use of the chararcteristic radiation from a lower atomic energy material giving rise to low energy X- rays (16-22 kev) .Target materials used for mammography  are  molybdenum (z=42) and rhodium (z=45),the former being most common. (Chapter 4,page no.74,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON MAMMOGRAPHY

473.True regarding mammography. 

a. aims to show microcacifications that may be 100micrometer or less

b. show tissues having much lower intrinsic contrast

c. atomic number of glandular tissues and adipose tissue (approx 7.4 and 6.5 respectively)

d. use of a broad bremsstrahlung spectrum  for imaging

e. target materials used for mammography  are tungsten ,molybdenum(z=42) and rhodium(z=45)

ANS OF PREVOIUS BLOG

465.True regarding causes of unsharpness in film –screen

a.thickness of phosphor

b.colored dyes

c.crossover

d.parallax

e.poor film-screen contact

465.acde--- Colored dyes  in the screen decrease  the unsharpness. (Chapter 4,page no.72-73,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON UNSHARPNESS

465.True regarding causes of unsharpness in film –screen

a.thickness of phosphor

b.colored dyes

c.crossover

d.parallax

e.poor film-screen contact

WRITE ANS IN THE COMMENT 

ANS OF PREVIOUS  BLOG

450.True regarding intensifying screen.

a.lanthanum oxybromide ,activated with  terbium ,emits a line spectrum of red light

b. lanthanum oxybromide ,activated with  terbium can be used with ordinary X-ray

c.Gadolinium and lanthanum oxysulphide activated with terbium emit yollow light

d. Gadolinium and lanthanum oxysulphide activated with terbium can be used with an orthochromatic film

e.red safe light is necessary in orthochromatic film while amber safe light is used with ordinary x ray film

450.bde----Lanthanum oxybromide ,activated with  terbium ,emits a line spectrum of blue light lanthanum oxysulphide activated with terbium emit green light. .(Chapter 4,page no.67,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON INTENSIFYING SCREEN

450.True regarding intensifying screen.

a.lanthanum oxybromide ,activated with  terbium ,emits a line spectrum of red light

b. lanthanum oxybromide ,activated with  terbium can be used with ordinary X-ray

c.Gadolinium and lanthanum oxysulphide activated with terbium emit yollow light

d. Gadolinium and lanthanum oxysulphide activated with terbium can be used with an orthochromatic film

e.red safe light is necessary in orthochromatic film while amber safe light is used with ordinary x ray film

ANS OF PREVOUS BLOG

436.True regarding heel effect

a.less intensity of x rays towards the cathode edge

b.steeper the target, the greater is the heel effect

c.reduced heel effect for a given film size at longer FFD

d.roughening increases the heel effect

e.place the thicker part of patients towards cathode side

436.bcd----Due to heel effect ,there is less intensity of x rays towards the anode edge  and so thicker part must be placed on cathode side. Heel effect is gradual,so not noticeable on even largest film. ---(Chapter 3,page no.62,second edition (2008),Farr’s Physics for Medical Imaging).

MCQ ON HEEL EFFECT

436.True regarding heel effect

a.less intensity of x rays towards the cathode edge

b.steeper the target, the greater is the heel effect

c.reduced heel effect for a given film size at longer FFD

d.roughening increases the heel effect

e.place the thicker part of patients towards cathode side

Put your ans in comment

A case of unusual foreign body in the urinary bladder

A case of unusual foreign body in the urinary bladder

22yrs male,history of hematuria

X-RAY PELVIS

COILS OF WIRE RETRIEVED DURING CYSTOSCOPY

The patients most likely concealed the history.Wire may have been self-inserted (?motive----???sexual ) or may have been forcefully inserted .

The case provided by DR SHAHAJ CHOPRA (RADIOLOGIST)