Version 2.0, free on Android and the web

Collimation practice for radtech students

Set the collimator on real positioning photographs for 24 upper-limb projections. ALARP scores each field against its target and shows where the central ray landed.

Try the web demo Download for Android

Wrist PAPractice

Accuracy (IoU)94.8%

CR offset0.5% · 0.5%

IR 8×10 inLengthwiseCR midcarpal

Evaluate & Save Collimation

Saved offlineWrist PA

Field matches the target: 94.8%

The collimation studio. Every field gets a score.

Pick a projection, drag the four blades around the anatomy and evaluate. ALARP compares your field with the target and saves the attempt.

PracticeSearch projections

Wrist PA Wrist · 8×10 in · Lengthwise 94.8%
Wrist lateral Wrist · 8×10 in · Lengthwise 88.1%
Wrist PA oblique Wrist · 8×10 in · Lengthwise New
Hand PA Hand · 10×12 in · Lengthwise 91.3%
Hand Norgaard Hand · 10×12 in · Crosswise New
Forearm AP Forearm · 14×17 in divided 86.0%
Elbow AP Elbow · 8×10 in · Lengthwise 90.2%
Elbow lateral Elbow · 8×10 in · Lengthwise New
Humerus AP upright Humerus · 14×17 in · Lengthwise New
Shoulder scapular Y Shoulder · 10×12 in · Lengthwise New
Shoulder AP external Shoulder · 10×12 in · Crosswise New

Wrist PASeated · forearm on the table · loose fistDiagnostic grade

Accuracy (IoU): 94.8%
Central ray X-offset: +0.5%
Central ray Y-offset: +0.5%
IR size: 8×10 in (18×24 cm)
IR orientation: Lengthwise
Central ray: Perpendicular, midcarpal area
Structures shown: Carpals, distal radius and ulna, proximal metacarpals

Study, practise and test in one app. Your progress stays on the phone.

Shows the steps for each projection

IR size, orientation, patient position, part position and central ray, following Bontrager’s positioning textbook.

Wrist PAPositioning guide

IR size: 8×10 in (18×24 cm)
Orientation: Lengthwise
Patient: Seated
Part: Forearm on the table, hand pronated, fingers in a loose fist
Central ray: Perpendicular to the IR, to the midcarpal area

Turns each bone in 3D

Rotate models of the hand, wrist, forearm, elbow, humerus and shoulder to see what the beam passes through.

A 3D model of the bones of the hand, seen from the palm side

Times you over 10 rounds

The challenge gives you 10 minutes for 10 projections. Each round asks for the position, IR size, orientation, patient position and field.

Upper Extremities Challenge07:42

Round 4 of 10 · Elbow AP. Which IR size?

8×10 in10×12 in14×17 in divided14×17 in

Keeps your history on the phone

Practise as a guest, even offline. Create an account later to sync your attempts and join the daily leaderboard.

Practice historyGuest · 2 waiting to sync

Wrist PAJust now94.8%
Wrist lateral12 min ago88.1%
Hand PAYesterday91.3%
Elbow APYesterday90.2%
Forearm AP2 days ago86.0%

24 projections, hand to shoulder. Each with its own target field.

Hand
PA, PA oblique, Lateral, Norgaard (ball-catcher)
4
Wrist
PA, AP, Lateral, PA oblique, AP oblique, Radial deviation, Ulnar deviation
7
Forearm
AP, Lateral
2
Elbow
AP, AP oblique, lateral, AP oblique, medial, Lateral
4
Humerus
AP upright, Lateral upright
2
Shoulder
AP external, AP neutral, AP internal, Transthoracic lateral, Scapular Y
5

A hand laid flat on an image receptor under the collimator light

A wrist in ulnar deviation on an image receptor under the collimator light

A forearm in lateral position on an image receptor

An elbow bent at a right angle on an image receptor

An upper arm against an upright image receptor

A shoulder turned for the scapular Y view against an upright receptor

Runs in your browser. The same app, nothing to install.

This is the Android app built for the web. The first load is about 9 MB.

Open Practice and pick a projection.
Drag the blades over the anatomy.
Press Evaluate & Save Collimation.

Questions students ask

Everything you need to know about positioning practice, textbook curriculum, and offline access.

Three students studying radiologic positioning together with ALARP

Is ALARP free?

Yes. The web demo and the Android app are both free.

Do I need an account?

No. Guest mode opens every lesson, practice and challenge. An account adds sync between devices and the leaderboards.

Does it work offline?

Yes, on Android. Lessons, targets and your attempts live in a database on the phone and upload when you are back online.

Which body parts does it cover?

The upper limb: hand, wrist, forearm, elbow, humerus and shoulder, 24 projections in all.

Which textbook does it follow?

Positioning steps, IR sizes and central rays follow Bontrager’s Textbook of Radiographic Positioning and Related Anatomy, 10th edition.

Is there an iPhone app?

No. On an iPhone or iPad, use the web demo in the browser.

Does it replace clinical instruction?

No. ALARP is a study aid. Positioning real patients is learned with a clinical instructor.

How do I delete my account?

In the app, open Profile and choose Delete My Account. Without the app, send a deletion request.