Radiology 10/28/2013 COLLIMATION CAN IMPROVE YOUR IMAGES COLLIMATION CAN IMPROVE YOUR IMAGES REVIEW OF BASIC X-RAY PHYSICS

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Griffin Tyler
5 years ago
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Radiology Hector RiveraMelo, DC, DACBR Director, Center for Diagnostic Imaging

IMAGES This film demonstrates limited collimation.

COLLIMATION CAN IMPROVE YOUR IMAGES This film demonstrates more collimation.

Know your patients The patient s size, shape and physical condition greatly

Most radiographic technique charts are based on the sthenic patient.

1 Radiology Hector RiveraMelo, DC, DACBR Director, Center for Diagnostic Imaging Southern California University of Health Sciences COLLIMATION CAN IMPROVE YOUR IMAGES This film demonstrates limited collimation. This allows for more scatter radiation to blur the image. COLLIMATION CAN IMPROVE YOUR IMAGES This film demonstrates more collimation. Otherwise, the same factors were used. Know your patients The patient s size, shape and physical condition greatly influence the required radiographic technique. Most radiographic technique charts are based on the sthenic patient. Factors that influence the sharpness of an image Focal spot size Source to Image-Receptor Distance (SID or FFD) Object to Image-Receptor Distance (OID) Geometric factors of the object Patient motion Scatter radiation Darkroom fog 1

Object to Image-Receptor Distance (OID) The

the less penumbra and the clearer the image.

the object will be magnified, giving lager

Scatter Radiation The more tissue exposed to

Therefore collimation is your best friend in

Scatter Radiation Grids are also an effective

can present issues with x-ray quality if not

Scatter Radiation Grids Properly aligned

2 Object to Image-Receptor Distance (OID) The closer the patient is to the image receptor, the less penumbra and the clearer the image. In addition to being blurrier around the edges, the object will be magnified, giving lager measurements on x-ray. Scatter Radiation The more tissue exposed to x-rays, the more scatter is produced. Therefore collimation is your best friend in eliminating scatter radiation. Scatter Radiation Grids are also an effective way of removing scatter Scatter Radiation Grids can present issues with x-ray quality if not installed correctly. Scatter Radiation Grids can present issues with x-ray quality if not installed correctly. Properly aligned focused grid Upside down focused grid Scatter Radiation Grids can present issues with x-ray quality if not installed correctly. Properly aligned crossed grid Upside down crossed grid 2

3 Scatter Radiation Alternatively, an air gap technique can sometimes be used But only at long FFDs Remember to use the anode heel to your advantage Remember to use the anode heel to your advantage Remember to use the anode heel to your advantage ARTIFACTS, WHERE DO THEY COME FROM? Static Electricity Static discharge occurs in low humidity environments. ARTIFACTS, WHERE DO THEY COME FROM? Static Electricity Static discharge occurs in low humidity environments. The artifacts may appear branching or circular. 3

the patient, but it is extremely important.

Drops of liquid In this case, drops of developer

other acidic liquid) landed on the unexposed film,

of time for the exposure will help prevent this

5s = 50mAs 500mA @ 0.1s = 50mAs Poor quality image.

Solution? Place the patient in the central ray!

4 ARTIFACTS, WHERE DO THEY COME FROM? Static Electricity They don t always occur as a result of human error. ARTIFACTS, WHERE DO THEY COME FROM? Technician Error It s easy to forget to properly gown the patient, but it is extremely important. Anatomy is covered. Is pathology covered? ARTIFACTS, WHERE DO THEY COME FROM? Drops of liquid In this case, drops of developer landed on the unexposed film, causing excessive exposure where they landed. ARTIFACTS, WHERE DO THEY COME FROM? Drops of liquid In this case, drops of fixer (or some other acidic liquid) landed on the unexposed film, preventing exposure where they landed. ARTIFACTS, WHERE DO THEY COME FROM? Patient Motion Reducing the total amount of time for the exposure will help prevent this artifact. 1.0s = 50mAs 0.5s = 50mAs 0.1s = 50mAs Poor quality image. What went wrong? Patient not in the central ray. Solution? Place the patient in the central ray! Tell the patient not to move! TROUBLESHOOTING 4

Underexposed mas too low FFD too far Solution?

Tell the patient not to move (or take supine)

TROUBLESHOOTING Funny looking image Double

Remember to remove/process film before exposing

TROUBLESHOOTING Multiple metallic artifacts.

Have patient properly gowned and remove jewelry.

5 TROUBLESHOOTING Poor quality image. What went wrong? Underexposed mas too low FFD too far Solution? Increase (double) mas Correct FFD Poor quality image. What went wrong? Patient not in the central ray. Image grossly underexposed. Solutions? Tell the patient not to move (or take supine) Increase (double) mas TROUBLESHOOTING TROUBLESHOOTING Funny looking image What went wrong? Double Exposure. Solution? Remember to remove/process film before exposing next image. TROUBLESHOOTING What went wrong? Multiple metallic artifacts. Earrings, Necklace Solutions? Have patient properly gowned and remove jewelry. TROUBLESHOOTING Poor quality image What went wrong? Over Exposure. mas too high FFD too close Solutions? Decrease (half) mas. Correct FFD TROUBLESHOOTING What went wrong? Multiple branching dark lines Static artifact Solutions? Ground yourself before opening the cassette Humidify the dark room 5

AP EXTERNAL ROTATION SHOULDER AP EXTERNAL

Profiles the greater tubercle laterally.

AP INTERNAL ROTATION SHOULDER AP INTERNAL

6 AP EXTERNAL ROTATION SHOULDER AP EXTERNAL ROTATION SHOULDER Arm is externally rotated. Profiles the greater tubercle laterally. coracoid process. AP INTERNAL ROTATION SHOULDER AP INTERNAL ROTATION SHOULDER Arm is internally rotated. Profiles the lesser tubercle medially. coracoid process. AP ELBOW AP ELBOW Forearm supinated. Radius and Ulna do not cross. antecubital fossa. 6

LATERAL ELBOW LATERAL ELBOW Must be flexed to 90

41 YOM WITH ELBOW SWELLING 41 YOM WITH ELBOW SWELLING

CPPD Gout Hemochromatosis Synovial chondromatosis

Myositis Ossificans SYNOVIAL CHONDROMATOSIS PA WRIST

More common in the large joints of the lower

7 LATERAL ELBOW LATERAL ELBOW Must be flexed to 90 degrees. Thumbs UP! 41 YOM WITH ELBOW SWELLING 41 YOM WITH ELBOW SWELLING DDx for soft tissue calcifications near a joint: HADD CPPD Gout Hemochromatosis Synovial chondromatosis Scleroderma Hyperparathyroidism Hypervitaminosis D Myositis Ossificans SYNOVIAL CHONDROMATOSIS PA WRIST Multiple calcified intraarticular loose bodies. More common in the large joints of the lower extremities. 2:1 Male predominant. Best for evaluating overall anatomy. Taken with a loose fist. Lunate. 7

8 PA WRIST LATERAL WRIST Great for seeing carpal alignment Able to evaluate anterior and posterior soft tissues LATERAL WRIST 12 YOM W/ TRAUMA AND WRIST PAIN R L 12 YOM W/ TRAUMA AND WRIST PAIN BILATERAL TORUS FRACTURES Typically seen in patients under the age of 20. Cortical buckling of the lateral radius. R L 8

$Is often accompanied by fractures of$ the ulnar styloid process.

9 36 YOM W/ TRAUMA AND WRIST PAIN 36 YOM W/ TRAUMA AND WRIST PAIN SCAPHOID FRACTURE 59YOF WITH FOOSH Typically seen in patients between the ages of Anatomic snuff box pain. Pain with wrist extension. May see deviation of the scaphoid fat pad. COLLES FRACTURE AP PELVIS Fracture of the radius with distal radius with posterior angulation. Commonly seen in patients >40 yo. Is often accompanied by fractures of the ulnar styloid process. Used to compare hips bilaterally. Hips should be internally rotated 10 degrees. 9

10 AP PELVIS FROG LEG HIP Hip is abducted and externally rotated. Used to evaluate the femur in a lateral projection. The posterior femur is projected inferiorly. FROG LEG HIP 60 YOM WITH RIGHT HIP PAIN 60 YOM WITH RIGHT HIP PAIN SEPTIC ARTHRITIS The hip is the most common extra-axial location. Phemister s triad seen in % of cases. Maintained joint space Erosions Something else Tuberculosis is a very common organism. 10

4 YOF WITH FLEXION CONTRACTURES OF THE KNEES AND HIPS CAUDAL

absent. Ilia will articulate with one another.

anomalies. 49 YOF WITH LEFT HIP PAIN Tumor or Infection?

Aggressive Large ST mass What type of tumor tissue?

It is the 3 rd most common primary aggressive bone tumor.

11 4 YOF WITH FLEXION CONTRACTURES OF THE KNEES AND HIPS CAUDAL REGRESSION SYNDROME Sacrum, coccyx and multiple lumbar segments may be absent. Ilia will articulate with one another. Associated with numerous other neurological and genitourniary anomalies. 49 YOF WITH LEFT HIP PAIN Tumor or Infection? Tumor Benign or Aggressive? Aggressive Large ST mass What type of tumor tissue? Cartilaginous CHONDROSARCOMA The average age is 45. It is the 3 rd most common primary aggressive bone tumor. Classically will have calcification within the lesion. May or may not see a large soft tissue mass. AP KNEE AP KNEE Best for evaluating tibiofemoral joint space. Can be taken standing or recumbent. apex of patella. 11

12 LATERAL KNEE LATERAL KNEE Knee must be flexed to 45 degrees Good for evaluating suprapatellar bursa distension 39 YOF WITH LEFT KNEE PAIN AGGRESSIVE GIANT CELL TUMOR Typically age range for is Can be highly expansile. Classically will involve a metaphysis of a long bone and extend into an epiphysis. 15 YOM WITH RIGHT KNEE PAIN 15 YOM WITH RIGHT KNEE PAIN 12

13 BONE SCAN Areas of elevated uptake Hot Spots indicate regions of increased metabolic activity DDx Infection Tumor Fracture 15 YOM WITH RIGHT KNEE PAIN 15 YOM WITH RIGHT KNEE PAIN 15 YOM WITH RIGHT KNEE PAIN OSTEOSARCOMA 44 YOF WITH RIGHT KNEE PAIN Age range is typically <25 May have purely blastic response. May see periosteal reaction or soft tissue mass. 13

14 SCLERODERMA AP ANKLE Typically age range for is Periarticular calcifications tend to be sheet-like. Distribution. Best for evaluating overall anatomy. Not to be confused with a DP foot view. CR between malleoli. AP ANKLE LATERAL ANKLE Gives good assessment of sagittal anatomy medial malleolus LATERAL ANKLE MEDIAL OBLIQUE ANKLE Great for seeing carpal alignment Able to evaluate anterior and posterior soft tissues 14

15 MEDIAL OBLIQUE ANKLE DP FOOT Best for evaluating overall anatomy. Foot should be flat on the cassette. Tube tilt of 10 degrees towards the head. Remember to place the anode towards the toes. DP FOOT LATERAL FOOT Great for seeing sagittal alignment Able to evaluate calcaneus well navicular LATERAL FOOT MEDIAL OBLIQUE FOOT Used to evaluate lateral mid-foot anatomy without overlap Especially good at evaluation the styloid of the 5 th metatarsal 15

16 MEDIAL OBLIQUE FOOT 25 YOM WITH LEG PAIN LINEAR BAND OF SCLEROSIS 25 YOM WITH LEG PAIN DDx for linear regions of sclerosis: Stress fx Heavy metal toxicity Scurvy Normal variant STRESS FRACTURE 10 YOM WITH LEFT ANKLE PAIN X-Rays may be normal or show linear sclerosis with or without callous formation On MRI, T2 weighted sequences will demonstrate a high signal region of bone marrow edema. Linear region of low signal on all MRI sequences. 16

10 YOM WITH LEFT ANKLE PAIN 10 YOM WITH LEFT ANKLE PAIN T1

Staphylococcus aureus is the most common bacterial agent.

17 10 YOM WITH LEFT ANKLE PAIN 10 YOM WITH LEFT ANKLE PAIN T1 T1+C STIR BRODIES ABSCESS 54 YOM WITH FOOT PAIN Most common in male children. Classic clinical presentation of localized limb pain which is often nocturnal. May preset and appear similar to an osteoid osteoma. Staphylococcus aureus is the most common bacterial agent. GOUT 57 YOM WITH FOOT PAIN Prominent soft tissue masses around the joints. Late in the disease process will show osseous erosions with overhanging margins. Male predominant. 17

18 NECROTISING FASCIITIS Extensive gas in the subcutaneous soft tissues. More likely to occur in patients with compromised immune systems. Can be fatal if not treated quickly. 19 YOM WITH RIGHT TOE PAIN 18

Radiology Positioning Practical Test #2 Table (By Jung Park):

Radiology Positioning Practical Test #2 Table (By Jung Park): (Lower Extremity): patient is fully gowned / no artifacts / properly shielded (exposure for femur and below : hold still, don t move ) (exposure