Precise bone age
for better patient care

BoneXpert is a software for automated measurement of bone age from a child's hand X-ray image. 200 hospitals have already integrated this tool seamlessly into their workflow for more consistent readings when dealing with growth disorders, optimisation of treatments and state-of-the-art adult height prediction.

The main uses of bone age in clinical practice are:

  • To assess whether the child is advanced or delayed in maturation
  • To assess increase of bone age between visits
  • To perform adult height prediction

The difference between manual and automated ratings:

When a specialized clinician does bone age assessment and is given sufficient time, they solve the task well. Problems arise however, when the bone age assessment becomes a repetitive task or different clinicians are involved. The advantages of using an automated system over manual ratings are:

Manual rating BoneXpert automatic rating
Manually assessing bone age introduces rater variability in the form of random errors and due to variation in the emphasis on the various bones. BoneXpert rating is standardised and objective, and uses modern reference curves to compute bone age SDS (standard deviation scores), which accurately describes the child’s bone age relative to healthy children of the same age, sex and ethnicity.
Assessing bone age manually introduces rater variability and random errors. These random errors are 0.58 years (SD) (Kaplowitz, 2011). BoneXpert rating is very precise: The random errors are 0.19 years (SD)
The problem with the traditional Bayley-Pinneau method is due to it being based on very old studies. Furthermore, it divides the children too crudely into advanced, normal and delayed bone age. BoneXpert uses a more accurate model developed and validated on modern data. It also allows the inclusion of parental height.

Additional benefits of BoneXpert

  • BoneXpert saves rating time, and can provide the result as soon as the X-ray has been recorded.
  • BoneXpert also assesses Bone Health Index (BHI), and gives BHI-SDS relative to modern healthy children of the same bone age and sex.

The BoneXpert workflow

The workflow is usually divided into two steps:

First, the X-ray is recorded in the radiology department and the bone age is determined by the BoneXpert Server – this can be done by the radiographer as soon as the image has been recorded.

Second, the pediatrician brings up the processed image using a suitable PACS image viewer, and reads the bone age value and performs the adult height prediction using a web-based calculator. Optionally the parental height can be used in the prediction.


BoneXpert Server is installed on Windows PC or virtual machine in the hospital and connected to the PACS as a "DICOM node". This setup is performed by the local PACS administrator.

The workflow with BoneXpert Server is illustrated above: After an X-ray is recorded, it is stored in the local PACS. A PACS user (a radiographer or radiologist) can then send the image to BoneXpert for analysis. After 10-30 seconds, BoneXpert returns an annotated X-ray, which is stored in PACS as a new image under the same Study. The PACS user does not directly operate a BoneXpert user interface, what is seen is simply the result: an additional image with the results of the analysis as an overlay; an example is shown here:

Technical description

BoneXpert Server is from a technical viewpoint a “DICOM Storage SCP/SCU” running as a Windows Service on a Windows computer connected to the PACS.

The software is set up via the configuration user interface shown below. Once it has been configured and started, it requires no active operation. The service receives DICOM hand X-rays, locates the bones in the image, computes the bone age and bone health index, and returns the result to the PACS as an additional image (or data set) in the same study.


BoneXpert Server can run on any existing Windows machine (physical or virtual) connected to the PACS. A single BoneXpert installation can service multiple hospitals, provided they share a common PACS, or if a DICOM network exists between hospitals with different PACS systems.

BoneXpert Server is not installed and integrated on the PACS itself, and it does not appear inside the PACS-programs with its own user interface, like some other plug-ins. It is better described as a “DICOM-node to send to and then receive from", or a “CAD-server”. So it resides at a “safe distance” from the PACS itself. Furthermore, BoneXpert has no Query/Retrieve, but simply accepts images sent to it by authorised PACS users or by auto-routing. The installation is very simple and can be performed in under twenty minutes by a PACS administrator.

Installation on the PACS side means enabling users to send to the BoneXpert DICOM node and allowing the BoneXpert DICOM node to push images back to the PACS.

When the service is running, any authorised PACS user can right-click on a hand image in the PACS client and select the "Send to BoneXpert service" button (which the PACS administrator has created):

Seconds later an additional image will automatically appear in the same “study” in the PACS client, i.e. it will be manifestly visible next to the original image:

So a radiologist can request the BoneXpert analysis “on demand”, when it is needed. Alternatively, the radiographer can send the image to the BoneXpert service as soon as it has been recorded. Or the PACS can be set up to route all new bone age X-rays (matching a suitable criterion, e.g. a RIS-code) automatically to the BoneXpert service.

The BoneXpert license is controlled by a username and password which are entered in the configuration user interface. The number of analyses performed is counted, and this is used as basis for the license agreement. BoneXpert server can be configured to use several license accounts, depending on the AE-title of the incoming image.

System requirements

BoneXpert 3.0+
Operating systems Windows 10 or newer
Windows Server 2016
Windows Server 2019
Windows Server 2022
Memory 4 GB RAM
Hard drive 3 GB Space
Software requirements .NET Framework 4.8 (runtime):
Microsoft Visual C++ 2010 Redistributable Package
Network settings Enabled internet with open port: 443 (default for HTTP Secure)
Connected to your PACS over the local network


The results are instantly available to the radiologist and the requesting clinician via the PACS viewer and can be read off from the image:

BA (GP):  Greulich-Pyle bone age with decimals
(M or F indicates the gender),
BA SDS: Standard deviation score (SDS, also known as Z-score) of GP bone age, based on Healthy Dutch children 1997
BA SDS >0 indicates advanced bone age
BA SDS <0 indicates delayed bone age
Carpal BA:
The overall GP bone age of the carpal region
BA (TW3): Tanner-Whitehouse-3 bone age, TW2 can also be shown
Age: Chronological age with decimals
BHI: Bone health index, based on cortical thickness of the metacarpals
BHI SDS: Standard deviation score of BHI

To obtain a 2-month free trial of BoneXpert Server for your institution, read more here.