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Requests. Who requests a DXA scan? DXA. DXA Technology. Adequate Clinical Information

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Requests

Requests

Define a protocol for validation and

Define a protocol for validation and

prioritisation of densitometry requests.

prioritisation of densitometry requests.

Registered medical practitioners

Registered medical practitioners

In writing

In writing

Include adequate clinical information

Include adequate clinical information

Unsuitable requests should be discussed

Unsuitable requests should be discussed

with referring doctor.

with referring doctor.

Who requests a DXA scan?

Who requests a DXA scan?

GPs GPs Orthopaedist Orthopaedist Rheumatologists Rheumatologists Oncologists Oncologists Obs/Gyn Obs/Gyn Geriatricians Geriatricians Radiologists Radiologists Gastroenterologists Gastroenterologists

Adequate Clinical Information

Adequate Clinical Information

Adequate Clinical Information

GENETICS/ FAMILY HX OF FRACTURE FEMALE > MALE

POST MENOPAUSE LOW BODY MASS INDEX LOSS IN HEIGHT FRAGILITY FRACURES SMOKING/XS ALCOHOL IMMOBILITY

MEDICATIONS: CORTICOSTEROIDS INFLAMMATORY BOWEL DISEASE HYPERPARATHYROIDISM ANOREXIA

MEN WITH LOW LEVELS OF TESTOSTERONE GENETICS/ FAMILY HX OF FRACTURE GENETICS/ FAMILY HX OF FRACTURE FEMALE > MALE

FEMALE > MALE POST MENOPAUSE POST MENOPAUSE LOW BODY MASS INDEX LOW BODY MASS INDEX LOSS IN HEIGHT LOSS IN HEIGHT FRAGILITY FRACURES FRAGILITY FRACURES SMOKING/XS ALCOHOL SMOKING/XS ALCOHOL IMMOBILITY IMMOBILITY MEDICATIONS: CORTICOSTEROIDS MEDICATIONS: CORTICOSTEROIDS INFLAMMATORY BOWEL DISEASE INFLAMMATORY BOWEL DISEASE HYPERPARATHYROIDISM HYPERPARATHYROIDISM ANOREXIA

ANOREXIA

MEN WITH LOW LEVELS OF TESTOSTERONE MEN WITH LOW LEVELS OF TESTOSTERONE

DXA

DXA

“GoldGold--standardstandard””for BMD measurementfor BMD measurement Measures

Measures ““centralcentral””skeletal sites: spine and skeletal sites: spine and

hip

hip

May measure other sites: forearm

May measure other sites: forearm

Extensive epidemiologic data

Extensive epidemiologic data

Validated in many clinical trials

Validated in many clinical trials

Widely available

Widely available

Low Radiation Dose

Low Radiation Dose

DXA Technology

DXA Technology

X-ray Source

(produces 2 photon energies with different attenuation profiles)

Photons Collimator

(pinhole for pencil beam, slit for fan beam)

Patient

Detector (detects 2 tissue types - bone and soft tissue)

Very low radiation to patient. Little scatter radiation to radiographer.

(2)

Radiation in DEXA

Radiation in DEXA

Ionizing Imaging Technique

Ionizing Imaging Technique

Too much is dangerous, must be limited

Too much is dangerous, must be limited

Patients, staff and public are at risk.

Patients, staff and public are at risk.

Adherence to License issued by the R.P.I.I

Adherence to License issued by the R.P.I.I

is necessary

is necessary

Adherence to local radiological safety

Adherence to local radiological safety

regulations is necessary

regulations is necessary

ALARA (As Low As Reasonably Achievable)

ALARA (As Low As Reasonably Achievable)

Local Rules for Bone Densitometry

Local Rules for Bone Densitometry

Local rules should be drawn up by radiation

Local rules should be drawn up by radiation

safety committee /

safety committee / licence licence holder.holder.

This will help ensure compliance with the RPII

This will help ensure compliance with the RPII

licence

licence conditions.conditions.

National Osteoporosis Society (NOS) provide

National Osteoporosis Society (NOS) provide

guidelines on local rules for DEXA.

guidelines on local rules for DEXA.

These local rules should be reviewed

These local rules should be reviewed

regularly and updated.

regularly and updated.

Local Rules for Bone Densitometry

Local Rules for Bone Densitometry

(NOS)

(NOS)

Operators must never

Operators must never

expose themselves in

expose themselves in

the X

the X--ray beamray beam During a scan only

During a scan only

the patient should be

the patient should be

within the controlled

within the controlled

area

area

Local Rules for Bone Densitometry

Local Rules for Bone Densitometry

(NOS)

(NOS)

The operators desk should be placed well

The operators desk should be placed well

outside the controlled area

outside the controlled area

Equipment not in use must be switched off

Equipment not in use must be switched off

and locked

and locked

If you become pregnant you must inform

If you become pregnant you must inform

your employer / RSO.

your employer / RSO.

Hazards of Ionizing radiation

Hazards of Ionizing radiation

Cancer induction by radiation

Cancer induction by radiation

Genetic effects of radiation

Genetic effects of radiation

Risks are greatest for the

Risks are greatest for the foetusfoetus

Need to ensure radiation protection of both

Need to ensure radiation protection of both

staff and patients

staff and patients

Radiation Protection of staff

Radiation Protection of staff

Never irradiate yourself in the X

Never irradiate yourself in the X--ray beamray beam

Stay outside of the Controlled Area while the

Stay outside of the Controlled Area while the

patient is being scanned

patient is being scanned

Be aware that scattered radiation from the

Be aware that scattered radiation from the

patient may be significant

patient may be significant

Position work station at least 2 m from the foot

Position work station at least 2 m from the foot

end of the scanning table

end of the scanning table

If the room size is too small to allow adequate

If the room size is too small to allow adequate

distance a lead screen should be employed

(3)

Radiation Protection of staff

Radiation Protection of staff

Wear a film badge on

Wear a film badge on

the side that the

the side that the

patient is being patient is being scanned scanned Radiation doses Radiation doses received by staff received by staff

should be within laid

should be within laid

down limits down limits An operator must An operator must declare their declare their pregnancy to the pregnancy to the RPO RPO

Radiation Protection of the patient

Radiation Protection of the patient

Justify and validate all scan requests

Justify and validate all scan requests

Operator must check patient ID and ask

Operator must check patient ID and ask

about pregnancy

about pregnancy

Perform scans in a safe manner while

Perform scans in a safe manner while

ensuring that dose is ALARA.

ensuring that dose is ALARA.

Pregnancy Status

Pregnancy Status

The unborn child is at

The unborn child is at

risk of ionizing risk of ionizing radiation radiation Radiation Protection Radiation Protection in pregnancy is in pregnancy is essential essential

Pregnancy Status Protocol

Pregnancy Status Protocol

for women under 50 years

for women under 50 years

Date of patients last menstrual period is checked

Date of patients last menstrual period is checked

Ask the patient if there is chance she might be

Ask the patient if there is chance she might be

pregnant

pregnant

Record this information in writing on the request

Record this information in writing on the request

form

form

Explain to the patient that this examination

Explain to the patient that this examination

involves a relatively small dose of radiation, and

involves a relatively small dose of radiation, and

this could be harmful to her foetus if she were

this could be harmful to her foetus if she were

pregnant

pregnant

Pregnancy Status Protocol

Pregnancy Status Protocol

If LMP is not within the first ten days the

If LMP is not within the first ten days the

scan should be postponed until the

scan should be postponed until the

beginning of the next menstrual cycle

beginning of the next menstrual cycle

However However

Referring doctor may waive the LMP rule

Referring doctor may waive the LMP rule

in writing

in writing

Referring doctor may justify the exposure

Referring doctor may justify the exposure

when the benefits of scan outweigh

when the benefits of scan outweigh

radiation risks

radiation risks

Duties of Staff

Duties of Staff

Small number of highly trained operators

Small number of highly trained operators

Obtain optimum scans

Obtain optimum scans

Operate to the departmental protocols

Operate to the departmental protocols

Consistent patient positioning and scan analysis

Consistent patient positioning and scan analysis

Perform routine QC

Perform routine QC

Adequate training in ionizing radiation

Adequate training in ionizing radiation

Participate in CPD

Participate in CPD

Retain professional membership of an

Retain professional membership of an

appropriate organization such as IOS and NOS

(4)

Patient Preparation

Patient Preparation

Identify correct patient

Identify correct patient

Date of birth Date of birth Sex Sex Race Race Weight Weight Height Height

Assess pregnancy status

Assess pregnancy status

Obtain previous scans

Obtain previous scans

Remove all metal objects from areas of interest

Remove all metal objects from areas of interest

Clear explanation of scanning procedure

Clear explanation of scanning procedure

Patient questionnaire

Patient questionnaire

Patient Questionnaire

Patient Questionnaire

Identify potential risk factors for

Identify potential risk factors for

osteoporosis

osteoporosis

Details of current medication

Details of current medication

Detail of skeletal fracture history

Detail of skeletal fracture history

Identify recent Imaging examinations

Identify recent Imaging examinations

which may affect the result

which may affect the result

Identify any hip or spinal orthopaedic

Identify any hip or spinal orthopaedic

surgery/ prostheses

surgery/ prostheses

Orthopaedic prostheses

Orthopaedic prostheses

Contrast Media

Contrast Media

Identify Artifacts

Identify Artifacts

Identify prior to scanning

Identify prior to scanning

Prevents repeats and unnecessary

Prevents repeats and unnecessary

radiation

radiation

Artifacts can be a major cause of error if

Artifacts can be a major cause of error if

undetected undetected

Artifacts

Artifacts

External or anatomical External or anatomical

Metal objects such as buttons and

Metal objects such as buttons and ““body body jewellary

jewellary””

Barium/ Contrast agent

Barium/ Contrast agent

Prostheses Prostheses Hickman Line Hickman Line Aortic Calcification Aortic Calcification Paget

Paget’’s diseases disease

Patient may not always report previous surgery

(5)

Optimum Scanning

Optimum Scanning

Measure patients weight and height

Measure patients weight and height

accurately

accurately

Identify artefacts

Identify artefacts

Record scan parameters

Record scan parameters

Use standard protocols for consistency

Use standard protocols for consistency

and comparability

and comparability

Use correct patient positioning and scan

Use correct patient positioning and scan

analysis

analysis

Ensure dose is ALARA

Ensure dose is ALARA

Protocols

Protocols

Patient Positioning Patient Positioning Scan Acquisition Scan Acquisition Scan analysis Scan analysis

Skeletal Sites to Measure

Skeletal Sites to Measure

Measure BMD at both the PA spine and hip in all

Measure BMD at both the PA spine and hip in all

patients patients

Forearm

Forearm

Forearm BMD should be Forearm BMD should be

measured under the

measured under the

following circumstances:

following circumstances:

– Hip and/or spine cannot be Hip and/or spine cannot be measured or interpreted measured or interpreted –

– Very obese patients (over the Very obese patients (over the weight limit for DXA table) weight limit for DXA table)

Good Positioning

Good Positioning

-

-

Spine PA

Spine PA

Straight spine in the center of the scanning

Straight spine in the center of the scanning

field

field

Equal amounts of tissue on either side of

Equal amounts of tissue on either side of

spine

spine

Knees flexed over 90

Knees flexed over 90°°support pad support pad Center 1.5cms below the anterior margins

Center 1.5cms below the anterior margins

of the iliac crests in the midline

of the iliac crests in the midline

ASIS equidistant from the tabletop

(6)

DXA LUMBAR SPINE

Good positioning

Good positioning

-

-

proximal

proximal

femur

femur

ASIS equidistant from the tabletop

ASIS equidistant from the tabletop

Whole leg rotated by 25

Whole leg rotated by 25°°

Leg abducted by 15

Leg abducted by 15°°to separate ischium to separate ischium

from lesser trochanter

from lesser trochanter

Center 5cm below the greater trochanter

Center 5cm below the greater trochanter

and in the midline of the femur

and in the midline of the femur

Arms positioned away from areas of

Arms positioned away from areas of

interest

interest

Positioning devices

Positioning devices

DXA HIPS

Vertebral Fracture Assessment

Vertebral Fracture Assessment

Densitometric spine

Densitometric spine

imaging performed for

imaging performed for

the purpose of the purpose of detecting vertebral detecting vertebral fractures fractures

Indications for VFA

Indications for VFA

When BMD measurement is low, When BMD measurement is low, performance of VFA should be performance of VFA should be

considered. Clinical situations that may considered. Clinical situations that may be associated with vertebral fractures be associated with vertebral fractures include:

include:

Documented height loss of greater than 2 Documented height loss of greater than 2

cm

cm

History of fracture after age 50History of fracture after age 50

Commitment to longCommitment to long--term glucocorticoid term glucocorticoid therapy

therapy

History and/or findings suggestive of History and/or findings suggestive of

Good Positioning

Good Positioning

-

-

LVA

LVA

Use of lateral support to position spinous

Use of lateral support to position spinous

processes of vertebrae parallel to the table

processes of vertebrae parallel to the table

Patient lies on left side with spine resting

Patient lies on left side with spine resting

against the support

against the support

Knees bent, arms positioned above the

Knees bent, arms positioned above the

head

head

Position lower back over curved support

Position lower back over curved support

Place pad between the knees

(7)

LVA

LVA Advantages

LVA Advantages

Assessment of vertebral Assessment of vertebral fracture status fracture status Low dose (1/100 of Low dose (1/100 of radiographs) radiographs)

Visualisation of the whole

Visualisation of the whole

spine in one view

spine in one view

Short scan time

Short scan time

Use of Further Imaging

Use of Further Imaging

Overweight patients

Overweight patients ––poor image poor image resolution

resolution

Mild fractures are suspected

Mild fractures are suspected

Limited visualisation of upper thoracic

Limited visualisation of upper thoracic

spine

spine

Large discrepancy in BMD between

Large discrepancy in BMD between

vertebrae

vertebrae

AP Spine Analysis

AP Spine Analysis

Individual vertebrae falsely elevated by artifact

Individual vertebrae falsely elevated by artifact

should be removed

should be removed

Include at least two vertebrae

Include at least two vertebrae

Label the vertebrae correctly

Label the vertebrae correctly

Correctly position

Correctly position IntervertebralIntervertebralROI boxesROI boxes In elderly patients the spine scan may be of little

In elderly patients the spine scan may be of little

value if there is extensive degenerative disease

value if there is extensive degenerative disease

Bone edge markers and

Bone edge markers and intervertebralintervertebralmarkers markers may need adjusting

may need adjusting

(8)

Hip Analysis

Hip Analysis

Use femoral neck or total proximal femur,

Use femoral neck or total proximal femur,

whichever is lowest

whichever is lowest

BMD may be measured bilaterally or at

BMD may be measured bilaterally or at

either hip

either hip

Check that the leg has been rotated and

Check that the leg has been rotated and

abducted correctly

abducted correctly

Check correct position of ROI boxes

Check correct position of ROI boxes

Check that bone edge markers are

Check that bone edge markers are

correctly positioned

correctly positioned

Hip Analysis

SEVERE OSTEOARTHRITIS

OF RIGHT HIP

Interpretation

Interpretation

Good Practice

Good Practice

Use of relevant reference ranges

Use of relevant reference ranges

Use of WHO guidelines

Use of WHO guidelines

Recommendations made on the lower of

Recommendations made on the lower of

the measurements at spine and hip

the measurements at spine and hip

Independent risk factors for fracture

Independent risk factors for fracture

Guidelines on management and follow

Guidelines on management and follow--upup

BMD in g/cm

BMD in g/cm22for each sitefor each site

The skeletal sites

The skeletal sites

The T

The T--score and/or Zscore and/or Z--score where appropriatescore where appropriate WHO criteria for diagnosis in postmenopausal

WHO criteria for diagnosis in postmenopausal

females and in men age 50 and over

females and in men age 50 and over

Explanation of results

Explanation of results

Risk factors including previous fragility fractures

Risk factors including previous fragility fractures

Fracture risk

Fracture risk

Unexpected results, for example a very high

Unexpected results, for example a very high

score for one vertebra which is out of context

score for one vertebra which is out of context

Indications for another imaging modality

Indications for another imaging modality

Baseline DXA Report sent to

Baseline DXA Report sent to

Doctor includes:

Doctor includes:

T

T--score/ Zscore/ Z--scorescore

Risk factors including previous nontraumatic

Risk factors including previous nontraumatic

fractures

fractures

Fracture risk

Fracture risk

Evaluation for secondary causes of low BMD

Evaluation for secondary causes of low BMD

Necessary Treatment

Necessary Treatment

Recommendations for the timing and

Recommendations for the timing and

necessity of your next BMD study

necessity of your next BMD study

Management and Follow up

Management and Follow up

(9)

Follow

Follow

-

-

up BMD Measurement

up BMD Measurement

Should only be done when the expected

Should only be done when the expected

change in BMD equals or exceeds the least

change in BMD equals or exceeds the least

significant change (LSC)

significant change (LSC)

LSC is the magnitude of change which must

LSC is the magnitude of change which must

be measured to be sure that the change is

be measured to be sure that the change is

real, not simply a result of measurement error

real, not simply a result of measurement error

Follow

Follow-

-up Scans

up Scans

Points to remember

Points to remember

Have previous scans available for review

Have previous scans available for review

Consistent patient positioning

Consistent patient positioning

Consistent scan analysis

Consistent scan analysis

Use of same software and scan compare

Use of same software and scan compare

facility

facility

Consistent approach between different

Consistent approach between different

operators operators

QA in DXA

QA in DXA

Regular scanning of Regular scanning of phantoms phantoms

Daily block phantom

Daily block phantom

System calibration

System calibration

QC phantom

QC phantom

Ensures that the DXA

Ensures that the DXA

equipment is equipment is operating as precisely operating as precisely and accurately as and accurately as possible possible

QA in DXA

QA in DXA

Follow manufacturer

Follow manufacturer’’s recommended IQC s recommended IQC protocol using the phantoms provided

protocol using the phantoms provided

Standard protocols for positioning

Standard protocols for positioning

phantom, acquisition and scan analysis

phantom, acquisition and scan analysis

Inspect results and report faults

Inspect results and report faults

Scanner Maintenance and Repair

Scanner Maintenance and Repair

--use of preventative maintenance programuse of preventative maintenance program

Summary

Summary

Compliance with referral guidelines

Compliance with referral guidelines

Benefits of exam must outweigh radiation risks

Benefits of exam must outweigh radiation risks

Careful consideration of appropriate technique

Careful consideration of appropriate technique

Operators should ensure that no person is

Operators should ensure that no person is

exposed to radiation more than is reasonably

exposed to radiation more than is reasonably

necessary

necessary

Consideration of frequency of follow up scanning

Consideration of frequency of follow up scanning

Radiation protection in pregnancy is essential

Radiation protection in pregnancy is essential

Use common sense: time, distance, shielding

Use common sense: time, distance, shielding

Useful Information

Useful Information

www.ios.ie www.ios.ie www.nos.org.uk www.nos.org.uk www.iscd.org www.iscd.org www. www.osteoporosis.caosteoporosis.ca www.osteofound.org www.osteofound.org www.nice.org.uk www.nice.org.uk

Royal college of Physicians, UK

Royal college of Physicians, UK

Osteoporosis International Journal

(10)

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