Direct X Ray Exposure on film

What is the Percentage(%) of the IMAGE DENSITY attributable to the direct X-Ray Exposure (and not the visible light) in a routine X-Ray image?

Ans : It's Only 5%.

Radiology Hints

Increasing voltage (kV) decreases contrast and increases exposure, making the film darker. Increasing milliampere-seconds (mAs) increases exposure, making the film darker.

 

Adrenal myelolipoma

Unilateral adrenal mass with chunky calcification and macroscopic fat, with -15 to -25 HU is suggestive of Adrenal Myelolipoma.

Fat containing Breast Lesions

Fat contained within a breast lesion points towards benign nature.

Mnemonic - HOT GaL.

Hamartoma
Oil cyst.
Traumatic Lipid cyst..fat necrosis.
Galactocele
Lipoma

Pearl Necklace gall Bladder - in Generalized form of Adenomyomatosis of Gall Bladder.

Adenomyomatosis of Gall Bladder

Focal or generalized thickening of Gall Bladder with Comet Tail artefacts
is characteristic of Adenomyomatosis Gall Bladder.
Thickenings originate from Rokistansky-Aschoff Sinuses.
Also characterized by coexistent cholesterol deposits with
their typical comet Tail artefacts and cystic intramural inclusions.
They are usually <10 HU on CT.

Radiation Dose units

Units of Radiation

1. 'Curie' and 'Becquerel' :- are radiation units for quantity of radionucleotide disintegration per second.

2. 'Rad', 'Gray', 'cGy' are units of Absorbed dose of Radiation.

3. 'Sievert' :- is the S.I. Unit of Equivalent dose of Radiation

What is Equivalent dose of Radiation ?

A: Equivalent dose of radiation = Absorbed Dose of Radiation x Weighing Ratio (WR). 

Radiation units

• Activity is the transformation (disintegration) rate of a radioactive substance
  • Curie (Ci)
  • Becquerel (Bq) - S.I. Unit

  1 Bq = 1 disintegration per second (dps)
  1 Ci = 3.7 x 10¹⁰ dps
  1 Ci = 3.7 x 10¹⁰ Bq

• Absorbed dose is a physical quantity which represents the energy imparted by radiation onto an absorbing material.
  • Rad
  • Gray (Gy) - SI Unit

    1 Gy = 1 joule per kilogram
    1 Gy = 100 rads
    

• Dose Equivalent (DE) may be regarded as an expression of dose in terms of its biological effect. DE takes account of the fact that, for a given absorbed dose, such as 1 Gray, a radiation of one type and/or energy may give rise to a greater biological effect than a radiation of another type and/or energy.
  
  

  DE = Absorbed Dose x Quality Factor (Q)

  • Q depends on the type of radiation.
    Q = 1 for gamma, x-ray and beta
    Q = 10 for alpha
    
    Q is used to compare the biological damage producing potential of various types of radiation, given equal absorbed doses. The effectiveness of radiation in producing damage is related to the energy loss of the radiation per unit path length. The term used to express this is linear energy transfer (LET). Generally, the greater the LET in tissue, the more effective the radiation is in producing damage.
  • REMS
    
  • SIEVERT (Sv) - S.I. Unit
    
    1 Sv = 100 rems
    
    
• Exposure is a quantity that expresses the ability of radiation to ionize air and thereby create electric charges which can be collected and measured
  • Roentgen (R)
    1 R = 2.58 x 10^-4 c/kg of air
  
  

INVESTIGATION OF CHOICE Contd...

*IOC in Mucosal study - Flexible Endoscopy

*IOC in Esophagial perforation (diagnosis) : Thin Barium Swallow.

(Note : Safest contrast in Tracheo-Esophagial Fistula - AIR > DAONOSIL)

*IOC in Deep Vein Thrombosis - Duplex Ultrasonography

(point to be noted here : "Most accurate for diagnosing DVT is - FIBRINOGEN SCAN)

*Best Method for detecting arterial trauma is - ARTERIOGRAPHY

*IOC in Aortic Aneurysm - Helical CT

MOST COMMONS : G.I.T Final

Most Common  Tumor of Small Intestine----Leiomyoma

Most Common  Type of intussusception----Ileocecal

Most Common  Benign Tumor of the Small Intestine----Leiomyoma

Most Common  Congenital anomaly of the esophagus----Esophageal atresia

Most Common  Malignant Tumor of Small Intestine----Carcinoid

Most Common  Tumor of Large Bowel----Adenoma

Most Common  Benign Tumor of the Large Bowel----Adenoma

Most Common  Malignant Tumor of Large Bowel----Adenocarcinoma

MOST COMMONS - G.I.T Part 1

1. Most Common  Benign esophageal tumor----Leiomyoma
   
2. Most Common  Cause of Small Bowel Obstruction----Adhesions
   
3. Most Common  Malignant tumor of esophagus----Squamous cell carcinoma
   
4. Most Common  Cause of Large Bowel Obstruction----Carcinoma of the colon
   
5. Most Common  Benign Tumor of Stomach----Adenomatous polyp
   
6. Most Common  Sources of Metastatic Lesions to Stomach----Melanoma and Breast ca
   
7. Most Common  Malignant Tumor of Stomach----Adenocarcinoma
   
8. Most Common  Cause of free air----Perforated ulcer
   

INVESTIGATION OF CHOICE

Hi all, under this section various IOCs will be posted.

IOC in Bronchiectasis - Spiral CT.

IOC in Pulmonary sequestration - Descending Abdominal Aortogram > CECT.

IOC in Motility disorders like Achalasia - Manometry

IOC in GE Reflux - 24 hr pH measurement

IOC in paraesophagial hernia - Barium meal + swallow

Most Commons - In Orthopedics

Most Common Bone in the wrist to fracture                         :  Scaphoid

Most Common Dislocation of the hip                                   : Posterior

Most Common Bone in the wrist to dislocate                        :Lunate

Most Common Dislocation of the shoulder                            :Anterior

Most Common Skeletal manifestation of multiple myeloma     :Osteoporosis

Most Common Bone tumor to complicate Paget's Disease        : Osteosarcoma

Most Common Bones involved by fibrous dysplasia                 : Pelvis, Femur

Most Common Parathyroid abnormality leading to 1* Hyperparathyroidism   : Adenoma

Most Common Cause of protrusio acetabuli                           : Rheumatoid Arthritis

Most Common Parathyroid abnormality leading to 2* Hyperparathyroidism : Hyperplasia

Most Common Bone involved by chondrosarcoma                    : Pelvis

Most Common Solitary, benign tumor of the ribs                      : Fibrous dysplasia

Most Common Site of osteochondritis dissecans                       : Medial femoral condyle

Most Common Humeral fracture in a child                                : Supracondylar

Most Common Benign boneMost Common tumor                                            : Enchondroma

Most Common Missed fracture of the elbow                             :Radial head fracture

Most Common Solitary, malignant, primary bone tumor              :Osteosarcoma

Most Common Metatarsal to undergo stress fracture                   : 2nd metatarsal

Most Common Malignant tumor of bone                                     : Metastatic bone disease

Most Common Portion of scaphoid to undergo avascular necrosis : Proximal pole

Signs in Radiology

1. Rabbit Ear Sign : Bilateral Subdural Hematomas in CT (Both frontal horns pointing poateriorly).

2. Dawson's Fingers : Multiple Sclerosis - MRI Brain (the result of inflammation around long axis of medularry veins)

3. Light Bulb sign - In posterior dislocation of shoulder.

4. Golden-S-Sign : Right upper lobe collapse in Chest X Ray.

5. 'Bat Wing Deformity of cerebral ventricles on CT/MRI - Agenesis of Corpus Callosum.

(AIIMS Nov'07 Expln)

6. 'Moth Eaten appearance' in V/Q Scan - Lung ----> Seen in BRONCHIOLITIS OBLITERANS.

(AIIMS Nov'07 Expln)

7. 'Reticular Pattern' in Chest CT ---> Follicular Bronchitis. (AIIMS Nov'07 Expln)

8. 'Sandstorm Appearance' or sand like appearance in Chest Radiography --> Seen in Pulmonary Alveolar Microlithiasis (P.A.M).

(AIIMS Nov'07 Expln)

9. Deep white matter lesion with bilateral bright thalami on C.T.--> KRABBE's Disease (Globoid Leukodystrophy).

(AIIMS NOV'07 Q)

10. Looser's Zones or Pseudofractures : Classically seen in Osteomalacia. (Also seen in Paget's, Fibrous Dysplasia, and osteoporosis)

11. Protusio Acetabuli and Triradiate Pelvis - Osteomalacia.

12. Rugger Jersey Spine - Osteopetrosis / Albers-Schonberg Disease /Marble Bone Disease and in Renal Osteodystrophy.

----------------------Congential Cardiac Diseases : Chest Radiography--------------------------------

13. Boot shaped heart / Cor en Sabot --- Tetralogy of Fallot.

14. Box Shaped Heart --- Ebstein's Anomaly.

15. Snowman Appearance / Figure of 8 Appearance - TAPVC (Asked 2 times in May 08 AIIMS)

16. Figure of 3 / Reverse Figure of 3 --- Coarctation of Aorta.

17. Goose Neck Sign --- Endocardial Cushion Defects.

18. Sitting Duck Sign --- Patent Truncus Arteriosus.

19. Scimitar Sign --- PAPVC - Partial Anomalous Pulm Venous Return.

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20. Scimitar Sacrum ---- Presacral Meningomyelocole.

21. Floating water Lily sign ---- Hydatid Cyst of Liver.

------------ Pulmonary Thromboembolism------------------------------------------------------------

22. Westermark's Sign --- Focal area of oligemia d/t vasoconstriction distal to embolus.

23. Palla's Sign -- Enlarged Right Descending Pulmonary Artery.

24. Hampton's Hump --- Peripheral Wedge shaped opacity in CXR d/t pulmonary infarct.

25. Fleischner Sign -- Local widening of artery d/t impaction.

26. Knuckle Sign -- Abrupt tapering of Occluded vessel distally.

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pgmeenotes by dv.