PEDIATRIC MEASUREMENT DEVICE FOR EARLY

DETECTION OF PLAGIOCEPHALY

IPHONE APP EDITIONCODY HALL

CHRIS HEELANJORGE PEREZ

CRANIOMETERProject goal

• To develop a low cost, safe, and accurate plagiocephaly measurement device for children aged infant to 24 months

• Digital solution that limits complexity as to lower price

Initial design• Physical Device

• Two digitial calipers used to detect linear distances and angles

CRANIOMETER PROS/CONS

PROSSimple Theory

• Directly sense angle using sensor• Calculate distances using

trigonometry

Simple UI• Three push buttons• Results clearly displayed on LCD

Easier to use with squirming childSimple design

• Increased reliability

Requires small investment by pediatrician

CONSHardware design

• PCB design/debugging• Component selection

Mechanical design• AutoCAD parts

Purchasing physical partsAssembling physical partsRequires physical contact with the infantThird-party required for manufacturing/marketing

IPHONE APPLICATIONNew design

• iPhone application• Use camera to take image of

infant’s head• Markers on paper provide

absolute distance calibration• PDF included with app

• Perform image analysis to calculate angles/linear distances

• Display results on phone

IPHONE APPLICATION PROS/CONS PROSUser already owns physical device

• No hardware to manufacture/purchase

Safer• No physical contact with child

App Store provides simple distribution methodFocus on purely software will allow for a more polished and professional productPotential Market

• Estimated 58,000 pediatricians in the United Stated (American Academy of Pediatrics)

• 94% of doctors own smartphones (compared to 59% in 2006)

• Doctors prefer iPhone (44%) to Blackberry (25%) and Andriod (25%)

• Estimated 24,000 potential customers• Verizon adding iPhone this year

CONSMore complex theory

• Calibrate pixels to distance using known markers in image

• Edge-detection processing to calculate linear distances

Requires pediatrician to own iPhoneMore complicated UI

• Also more complicated to design

Harder to use with squirming child• Camera must be parallel to child’s head

Requires designers to learn Cocoa (Objective-C) programming

HOW DO WE KNOW THIS WILL WORK?iPhone 4 Camera Specifications

• Back- Illuminated CMOS Sensor• 5-Megapixel Resolution (2592 x

1936)• Fixed aperture f/2.8• Permanent 3.85mm focal length

IPHONE CAMERA TESTINGThird party research

• <0.2% barrel distortion = Very GoodLow noise

• <2% under fluorescent lighting (ISO 144)Need to determine sharpness

• Rise distance

RESOLUTION30cm x 22cm area / 2592 x 1936 pixelsGives us a 0.13mm spatial resolution under perfect conditions

SEGMENTATION AND EDGE DETECTIONUse of histogram threshold

CONNECTED COMPONENT LABELING

NECESSARY LABELING METHOD TO MARK DIFFERENT CIRCLES

FIND THE CENTERS OF CIRCLES- STRIKE A CHORD

Find the maximum distance from one point on the edge to anotherTake midpoint as centerDistance between centers is determines pixel size

EDGE DETECTION ON A REAL PHOTO

CHALLENGESDeveloping efficient algorithms to work on iPhoneAutomated or assisted point selection process- GUI controlMaintaining millimeter resolution during heavy image processing

IPHONE APP DEVELOPMENTRequired

Computer running Mac OS-two designers own OSX machines

Register with Apple as a developer-two designers registered

Download/install SDK-two designers have successfully installed/used the SDK

Create application

Submit application to App Store for approval

HELLO WORLD! APP

APPLICATION PROGRAMMING

Learning Cocoa (Objective-C)• Stanford iPhone app development

lectures• Free from iTunes University• Full semester course (lecture videos

and PPT slides)• Other online coding/app tutorials• One team member proficient in C

programming• Layer underneath Objective-C

• One team member proficient in Java programming

• Object-oriented programming

IMAGE PROCESSING ALGORITHMSImageJ

• Free image processing program• Open source Java code• Port needed algorithms to Objective-C

• One designer proficient in JavaIndependent research

• Image processing tutorials online in many different coding languages

IMAGE PROCESSING LOCATIONTwo choices for image processing

• All processing written within application (Objective-C)• App is completely localized

• Processing performed on server running Python script• App captures/displays image and provides GUI• App sends image to server• Image processing offloaded to Python• Script sends results back to app