Long Bone Measurement

Front 1

Long bone measurement is most frequently applied to the

Back 1

lower limbs

Front 2

How many x-ray exposures are required during a long bone measurement study

Back 2

3 exposures

Front 3

What is the patient position for a long bone measurement

Back 3

supine

Front 4

Which of the following is the projection used for long bone measurement radiographs

Back 4

AP

Front 5

Which of the following iscurrently the examination method of choice for long bone measurements due toits accuracy and reduced dose?

Back 5

CT

Front 6

Long bone measurement is used to evaluate for

Back 6

limb length discrepency

Front 7

Long bone measurement may be accomplished by

Back 7

1. radiography

2. MRI

3. CT

4. US

5. microdose digital radiography

Front 8

Three radiographic methods

Back 8

1. orthoentgenogram

2. scanogram

3. teleoroentgenogram

Front 9

Which two methods require three precisely centered exposures at the hip, knee, and ankle joints and include the use of a radiopaque ruler taped to the table between the limbs?

Back 9

orthoentgenogram and scanogram

Front 10

What is the primary difference between the 3 methods?

Back 10

IR size

Front 11

Orthoentgenogram

Back 11

1. uses a single IR

2. IR remains stationary

3. table and xray tube move to an unexposed station

Front 12

Scanogram

Back 12

1. uses three separate IRs

Front 13

Teleroentgenogram

Back 13

1. single upright AP exposure

2. both limbs

3. special long IR

4. SID of at least 6 ft (180cm)

Front 14

Digital postprocessing does what?

Back 14

stitches the 3 images together for equally accurate measurements of entire lower limbs

Front 15

This makes radiation dose

Back 15

lower than used in the film screen methods

Front 16

What is most frequently applied to the lower limbs>

Back 16

radiography

Front 17

Orthoroentgenology

Back 17

a radiographic technique used to determine the exact length of a limb

Front 18

Especially the differences between

Back 18

two sides

Front 19

Orthoroentgenology is usually performed on

Back 19

lower limbs

Front 20

Orthoroentgenology: PATHOLOGIC INDICATIONS

Back 20

1. back pain due to leg length differences

2. developmental abnormalities

3. epiphysiodesis

4. bone lengthening surgery

Front 21

Epiphysiodesis

Back 21

surgical procedure to shorten a limb

Front 22

The purpose of long bone measurement is to determine what

Back 22

limb length discrepancy, which occurs primarily in children

Front 23

Because patients might require regular check ups, what protection is essential?

Back 23

Gonadal

Front 24

How many exposures are made of the limb>

Back 24

3

Front 25

If large discrepancy exists, what exam is recommended

Back 25

unilateral

Front 26

If small discrepancy

Back 26

bilateral is accurate

Front 27

Upper limb exposures are made at what 3 areas

Back 27

shoulder, elbow wrist

Front 28

Lower limb exposures are made at what 3 areas

Back 28

hip, knee, ankle

Front 29

Which radiography yields the lowest dose but requires specialized equipment which can be cost- prohibitive

Back 29

microdose digital radiography

Front 30

Which two modalities have promise as means to safely image for long bone measurement

Back 30

MRI and US

Front 31

Recent research demonstrating ____ % accuracy and reliability for ___ measurments

Back 31

99, MRI

Front 32

Accuracy of the exam depends on the patient

Back 32

not moving the limb/limbs even slightly

Front 33

Small children must be

Back 33

carefully immobilized to prevent motion

Front 34

Where do you place the patient for othoroentgenography and scanography?

Back 34

supine

Front 35

Where do you place the patient for digital teleoroentgenogram?

Back 35

standing, upright backed up closely to vertical bucky device

Front 36

Both sides are examined for

Back 36

comparison either separately or simultaneously for all techniques

Front 37

When soft tissue abnormality is causing rotation of the pelvis

Back 37

elevate low side on radiolucent support to overcome the rotation

Front 38

Adjust and immobilize the limb for a ___ projection

Back 38

AP

Front 39

If two lower limbs are examined simultaneously, separate the

Back 39

ankles 5-6 inches and place the specialized ruler under the pelvis and extended down between the legs

Front 40

If limbs are examined separately, position the patient with

Back 40

a special ruler beneath each limb

Front 41

When knee of patients abnormal side cannot be fully extended,

Back 41

flex the normal knee to the same degree and support each knee on one of a pair of supports of identical size to ensure that the joints are flexed to the same degree and are equidistant from the IR

Front 42

To localize each joint accurately, what should you use to indicate the CR centering point?

Back 42

skin marking pencil

Front 43

Because both sides are examined for comparison and discrepancy in bone length usually exists, mark the joints of

Back 43

each side after the patient is in the required position

Front 44

Upper limbs - place the marks as follows

Front 45

Shoulder joint

Back 45

over superior margin of the head of the humerus

Front 46

Elbow joint

Back 46

1/2 to 3/4 inch below the plane of the epicondyle of the humerus

Front 47

Wrist joint

Back 47

midway between styloid processes of the radius and ulna

Front 48

Lower limbs - place the marks as follows

Front 49

Hip joint

Back 49

1 to 1 1/4 inches laterodistally and at a right angle to the midpoint of an imaginary line extending from the ASIS to the pubic symphsis

Front 50

Knee joint

Back 50

just below the apex of the patella at the level of the depression between the femoral and tibial condyles

Front 51

Ankle joint

Back 51

directly below the depression midway between the maleoli

Front 52

All images are made by

Back 52

a single x-ray exposure

Front 53

the image is larger than the actual body part because

Back 53

xray photons start at a small area on the target of the xray tube and diverge as they travel in straight lines through the body to the IR

Front 54

This magnification can be decreased by putting the body part as

Back 54

close to the IR as possible, using the maximum SID allowed by the equipment

Front 55

Orthoroentgenography

Back 55

metal measurement ruler placed between the patients lower limbs, three exposures made on same xray IR - centered to each joint, beginning at most proximal joint

Front 56

Following steps are taken

Front 57

use what type of collimation

Back 57

narrow/close for improved image quality and radiation protection

Front 58

Carefully center of limb parts to the

Back 58

upper, middle and lower thirds of the IR - making 3 exposures

Front 59

For all 3 exposures, place CR

Back 59

perppendicular to and passing directly through the specified joint

Front 60

"Orthos" meaning

Back 60

straight

Front 61

DO NOT move the

Back 61

limb between exposures

Front 62

Where is the IR for all exposures

Back 62

bucky tray

Front 63

Position the xray tube directly over the patients hip

Back 63

make first exposure

Front 64

Position the xray tube directly over the patients knee joint

Back 64

make 2nd exposure

Front 65

Position the xray tube directly over the patients ankle joint

Back 65

make 3rd exposure

Front 66

Move the __ not the patient

Back 66

tube

Front 67

If the child holds the leg perfectly still while the 3 exposures are made, the true distance from the

Back 67

prox end of the femur to the distal end of the tibia can be directly measured on an image

Front 68

Method using CT to measure

Back 68

discrepancies in leg length

Front 69

What is more consistently reproduced and causes less radiation exposure to the patient than conventional radiography

Back 69

CT scanogram

Front 70

Take what type of image

Back 70

CT localizer or "scout" images of femurs and tibias

Front 71

Place ___ over the respective hip, knee and ankle joints

Back 71

cursors

Front 72

For upper limbs obtain scout images of

Back 72

humerus, radius, ulna

Front 73

Measurements are displayed on

Back 73

cathode ray tubes

Front 74

The accuracy of CT exams depends on

Back 74

proper placement of cursors

Front 75

Accuracy improved when the cursors were placed

Back 75

3x and values obtained were averaged

Front 76

CT exams used radiation doses that were __ to __ times less than those used with conventional radiography

Back 76

50-200

Front 77

CT doses as ___ % less than that of orthoroentgenograms

Back 77

80%

Front 78

The purpose of orthoroentgenography

Back 78

To measure the length of long bones

Front 79

Into which body position should the patient be placed when an exam to measure long bones is performed?

Back 79

supine

Front 80

Which parameters should be moved when exposures for long bone measurement are made

Back 80

xray tube and IR

Front 81

Which special device must be used for long bone measurement exams

Back 81

metal ruler

Front 82

For exposures made at the knee joint, the CR should be directed to which of the following levels

Back 82

depression between the femoral and tibial condyles

Front 83

For orthoroentgenography, how many exposures should be made of each limb

Back 83

3

Front 84

For simultaneous bilateral projections of the lower limbs, how many exposures should be made

Back 84

3

Front 85

WHich procedure must be performed to ensure accuracy in long bone measurement exams

Back 85

do not move the limb between exposures

Front 86

FOr long bone measurement of the lower limbs, which procedure should be performed when the patient's right leg is noticeably shorter than the left leg

Back 86

radiograph both legs

Front 87

How should the lower limbs be positioned for bilateral projections of the lower limbs

Back 87

In anatomic position with slight medial rotation

Front 88

List imaging methods used to evaluate limb length discrepancy

Back 88

orthoroentgenorgram, scanogram, teleoroentgengram

Front 89

What area of the body is more frequently radiographed for long bone measurement

Back 89

lower limbs

Front 90

How many exposures should be made of each limb

Back 90

3

Front 91

WHy might movement by the patient cause the exam to be repeated

Back 91

could affect the accuracy of the measurement

Front 92

What type of projection should be performed

Back 92

AP

Front 93

With reference to the affected lower limb, where should the metal ruler be placed when only one limb is imaged

Back 93

under the affected leg and on top of the table

Front 94

What procedure should be performed to the normal knee when the abnormal knee cannot be fully extended

Back 94

flex the normal knee to the same degree and support both knees on supports of identical size

Front 95

If the right side is shorter than the left side, which side should be radiographed

Back 95

both sides should be radiographed

Front 96

Why is the image of a limb made by a single xray exposure larger than the actual limb

Back 96

the ends of bones are imaged with divergent rays' therefore some magnification is produced

Front 97

What two steps can the radiographer take to reduce the magnification produced when a single exposure is used to image a limb

Back 97

1. uses minimum OID

2. uses max SID possible

Front 98

Why does orthoroentgenography produce more accurate long bone measurements than a single exposure exam

Back 98

because the CR is perpendicular to and passes through the specified joint for each exposure

Front 99

How is bone length determined with orthoroentgenography

Back 99

by subtracting the numeric values projected over the selected limb

Front 100

For simultaneous bilateral projections of lower limbs, where should the CR be directed for each exposure

Back 100

to the midline of the table between two similar joints

Front 101

Describe how the lower limbs should be adjusted for simultaneous bilateral projections of the lower limbs

Back 101

in the anatomic position with slight medial rotation

Front 102

What body plane of the patient should be centered on the table for simultaneous bilateral projections of the lower limbs

Back 102

MSP

Front 103

With reference to the lower limbs, where should the metal ruler be placed when both lower limbs are simultaneously imaged

Back 103

at the top of the table so that part of it is included in each of the exposure fields

Front 104

How many times should the patient be positioned when simultaneous bilateral projections of the lower limbs are made

Back 104

one

Front 105

For simultaneous bilateral projections of the lower limbs, what procedure should be performed to correct an exam when bones of different lengths cause bilateral distortion

Back 105

examine each limb separately

Front 106

List two advantages that obtaining long bone measurements with CT has over the conventional radiographic approach

Back 106

1. more consistent reproduction of the image

2. less radiation dose to the patient