Measurement overview
Basic steps for a patient measurement
There are five basic steps necessary to complete a patient measurement. These steps must be completed in the order given. Review the five steps before you start a patient measurement. Click on a topic below for more information:
Step 1: Record or select patient 
Step 2: Select measurement site 
Step 3: Position patient 
Step 4: Adjust measurement start position 
Step 5: Start measurement 

Patient considerations
Obey the patient considerations that follow before you start a patient measurement:
·	Clothing restrictions: Make sure the patient removes items that can attenuate the x-ray beam; such as clothing with zippers, snaps, buckles, and buttons. Ask patients to wear a jogging suit to the exam or give them an examination gown when they arrive.
·	Radionuclides and radiopaque agents: Make sure the patient has not ingested or been injected with radionuclides or radiopaque agents in the past 3–5 days. If the patient has taken tests that use such agents, postpone the measurement until all traces of the element have left the patient’s body. A 72-hour waiting period is usually long enough for most agents to leave the patient’s body. However, consult your radiation safety officer (RSO).
·	Pregnancy restrictions: If it is necessary to measure a pregnant patient, the fetus could be exposed to small amounts of radiation. Postpone the measurement until the end of pregnancy if clinical management is not affected. The decision to subject a fetus to radiation exposure must be made by the referring physician, noting that 1) bone quality for most patients does not significantly change during pregnancy and 2) in the advanced stages of pregnancy, the fetus’ mineralized bone can interfere with measurements of the mother’s spine and femur.

Record or select patient
To complete a patient measurement, you must record information for a new patient or select a patient from the database.
 Continue to Select measurement site

Select measurement site
The New Measurement screen shows a skeletal image which gives the sites you can select to measure. Use the mouse to click on the site you want to measure. The site you select is highlighted in the Site(s) list, and the appropriate measurement mode for the patient is highlighted in the Mode(s) list.
Note for LVA: select Lumbar to measure only the lumbar vertebrae. Select LVA to measure the entire spine.
 Continue to Position patient

Position patient
1.	Make sure all attenuating materials (belts, metal buttons, etc.) are removed from the measurement region.
	For Total Body scans, all materials that may cause significant attenuation must be removed.
2.	Position the patient on the scanner table.
	AP Spine, Femur, DualFemur, and Total Body position 
	Forearm position 
	LVA position 
3.	Select Position from the New Measurement tool bar. The scanner arm moves to the approximate start position.
	For Forearm measurements, be careful that the scanner arm does not bump the patient’s head.
4.	A graphic is shown that gives the correct patient position, and measurement start position, for the site you are measuring. Click on a topic below to position the patient for a specific site:
·	AP Spine 
·	Femur/DualFemur 
·	Total Body 
 Continue to Adjust measurement start position.

Position patient: AP Spine
Use the support block to elevate the patient’s legs. Make sure the patient’s thighs form a 60°–90° angle with the table top. This step helps separate vertebrae and flatten the lower back.

Position patient: Femur and DualFemur
Use the centerline on the scanner table as a reference to make sure the foot brace is centered. Align the centerline with the guide on the base of the foot brace. Internally rotate the patient's legs, and secure the patient’s feet to the foot brace (do not remove the patient’s shoes).

Position patient: Total Body
Remove the patient’s shoes. Make sure the patient’s head is approximately 3 cm below the horizontal line on the table pad. Use the velcro straps to secure the patient’s knees and feet to prevent movement during the measurement.

Adjust measurement start position
Use the graphic shown on the New Measurement screen and the basic techniques that follow to adjust the position of the laser light:
·	AP Spine–position the laser light approximately 5 cm below the patient’s navel and in the same longitudinal plane as the patient’s midline.
·	Femur–position the laser light approximately 7–8 cm below the greater trochanter where the transverse (Pubic Symphysis) and midline of the femur intersect. If you are completing a DualFemurä measurement, position the laser light for the left femur first. 
·	Forearm–if necessary, move the positioner and the 
patient’s arm so that the laser light shines in the center of the patient’s arm and is aligned with the blue line on the forearm positioner. Make sure the patient’s elbow makes a 90-degree angle, and make sure the forearm positioner is straight on the table top.
·	LVA–position the laser light at the top of the patient’s iliac crest.
	Note: You are not required to adjust the laser light for Total Body measurements.
	WARNING:	Each LUNAR scanner is equipped with a Class II Laser that is less than 1 milliwatt in strength. DO NOT STARE INTO THE BEAM.	

 Continue to Start measurement

Start measurement
Select Start from the New Measurement tool bar tool bar to start the measurement. Monitor the image to make sure it is correct.
 Continue to End the measurement

Monitor AP Spine measurement
	Make sure the spine is in the center of the image, all of L4 (1) is shown, the top of L5 (2) is shown in the first 1-2 sweeps of the detector, and (3) approximately ½ of T12 is shown.
If the image is not correct, select Abort, reposition the laser light, and restart the measurement.
 Continue to AP Spine analysis	

Monitor Femur measurement
	A correct Femur image shows the greater trochanter (1), femoral neck (2), and ischium (3). 
A minimum of three centimeters of tissue (2-3 sweeps of the detector) should be shown above the greater trochanter and below the ischium.
If the image is not correct, select Abort, reposition the laser light, and restart the measurement.
DualFemur
After the program has measured the left femur, the scan arm moves to the approximate start position for the right femur. Check the start position and, if necessary, adjust the measurement start position for the right femur.
 Continue to Femur analysis
  Continue to DualFemur analysis	

Monitor Total Body measurement
	A correct Total Body image shows the entire body. Make sure the head, feet, and patient’s arms are included in 
the image.
If the image is not correct, select Abort and reposition the patient.
 Continue to Total Body analysis	

Monitor Forearm measurement
	Make sure the forearm is in the center of the image and the distal end of the ulna
(1) is shown near the top of the image.
If the image is not correct, select Abort, reposition the laser light, and restart the measurement.
 Continue to Forearm analysis	

Monitor LVA measurement
	Make sure the image is correct.
1	The image starts near the top of the iliac crest.
2	At least 2.5 cm of soft tissue is shown on the anterior side of the vertebrae.
3	The image ends in L1 for a Lumbar measurement or near T4 for an LVA measurement.
4	All of the posterior elements appear in the image.
5	The edge of the positioner may appear in the image. This is not a problem.
If the image is not correct, select Abort, reposition the laser light, and restart the measurement.
 Continue to LVA analysis	

End measurement
When the measurement is completed, select Home to move the scanner arm to the Home position. Select Close to exit the New Measurement screen. Help the patient off of the scanner table.
 Continue to Analyze the image

Abort measurement
Select Abort from the New Measurement tool bar if the image is not correct or if you determine that a sufficient area of the measurement is obtained. 
When you select Abort, the measurement stops automatically when the detector reaches the edge of the scan window. A message shows the options that follow:
·	"Save Measurement"–Select this option to save the current measurement.
·	"Do not save measurement. Reposition this measurement"–Select this option to start the measurement again using the same settings.
	The box that is shown around the image shows the measurement area. Use the arrow keys to move the box and reposition the measurement.
	Select Start from the New Measurement tool bar to restart the measurement
·	"Do not save measurement. Set up a new measurement"–Select this option to change the settings for the measurement.

DualFemurä measurement
DualFemur lets you measure the patient's right and left femur in an automatic sequence. The DualFemur positioner positions both femurs at one time, which lets the SmartFan™ feature find the contra-lateral femur with no repositioning of the patient.
Use the left and right femur densitometry information to determine lowest BMD, and use the average BMD to compare subsequent DualFemur measurements. The use of the average BMD can improve precision by 30%.
 Continue to Measurement overview

AP spine, Femur, DualFemur, and Total Body position
Help the patient onto the scanner table.
1.	the patient’s hands are flat with the palms down on the scanner table and arms are alongside the patient’s body.
2.	the patient’s body is in the center of the scanner table—use the centerline on the table as a reference to align the patient. 

Forearm position
1.	Put the forearm positioner on top of the pad. The LUNAR logo should be located near the patient’s fingers.
2.	Seat the patient in a chair next to the scan table.
Note: Use a chair without arms or wheels. Use the same chair for all forearm measurements to get optimal precision.
3.	Tell the patient to make a loose fist, and position the forearm so that it is centered between the black lines on the positioner. Align the distal end of the ulna with the blue line on the positioner.
4.	Attach the velcro straps over the fist and over the arm immediately below the elbow. The straps must be outside the measurement region.
5.	Select  Position from the New Measurement tool bar. The scanner arm moves to the approximate start position.

Forearm positioner
The forearm positioner keeps the patient’s forearm from moving during a measurement.
1.	Put the positioner on top of the pad so that the LUNAR logo is located near the patient’s fingers.
2.		The red line shows the center of the measurement area. Center the patient’s forearm along this line.
3.	The black lines show the boundary of the measurement area. Position the patient’s forearm so that both the radius and ulna are between these lines.
4.	The blue line shows the starting point of the measurement. Position the patient’s forearm so the distal end of the ulna is at this line. Also, position the laser light at this line when you start a measurement.

LVA position
1.	Put the lateral positioner (1) on the table so that it is on top of the spine strap (2) and against the back edge of the table.
2.	The lateral positioner and the instructions below are intended to position the lumbar spine straight and parallel to the scanner table. Refer to the figure below to complete the steps that follow.
·	Set a foam cylinder (1) or pillow on the table for the patient’s head and a tapered foam wedge 
(2) for the waist.
·	Position the patient’s knees toward the chest until the lower back is flat against the lateral positioner.
·	Make sure the patient’s spine (3) is parallel to the scanner table: adjust the tapered wedge below the waist until the patient’s hips and shoulders create a straight line parallel to the table.
3.	Refer to the figure below to complete the steps that follow.
·	Pull the compressor strap (1) over the patient’s torso and secure it to the back of the positioner. Make sure the strap does not hang over the back edge of the scanner.
·	Set a foam wedge between the patient’s thighs and the bottom of the positioner (3). Set a second wedge between the patient’s knees (2), and set a third wedge below the bottom knee (2). Make sure the patient’s back is flat against the positioner and adjust the strap so the patient does not roll forward during the measurement.
·	Adjust the foam wedge (3) between the back of the patient’s thighs and the positioner to hold the knees in place during the measurement.

Home scanner arm
Select Home Scanner from the Measure menu to move the scanner arm to the Home position from any screen in the program.

Pediatrics
The Pediatric option lets you get BMD and Z-score values for females and males who are 5–19 years old. Measurement and analysis procedures are the same as the procedures for adult patients.
Reference values are available for AP spine and Total body measurements. T-score values are not given because the T-score is related to peak bone density, and pediatric patients have not yet reached their peak bone densities. T-score should not be used for diagnosis and management of pediatric patients.