Better lung health for all
Quality Improvement

PN Risk Calculator

These risk predication calculators are provided to assist clinicians in relation to the diagnosis and management of pulmonary nodules – the information provided here should be used in conjunction with the BTS guideline for the investigation and management of pulmonary nodules, and the detail of each model is given via the links below.

Please read the disclaimer and check the box to indicate that you accept the terms of use - links to each calculator will then be displayed.


The risk prediction calculator tool ("RPCT") functionality made available on this page is provided "as is" with no warranties whatsoever.

The British Thoracic Society, on its own behalf and on behalf of all of its service providers associated with the RPCT ("BTS") and its licensors, hereby expressly exclude to the fullest extent permitted by law all express, implied, and statutory warranties and conditions including, without limitation, warranties and conditions of merchantability, fitness for any particular purpose, non-infringement of proprietary rights, security, reliability, timeliness, and performance.

You hereby acknowledge and agree that: (a) your use of the RPCT is entirely at your own discretion and risk; (b) BTS excludes all liability for any loss or damage arising from such use to the fullest extent permissible by law; (c) the RPCT is for information purposes only, you are not entitled to base any treatment or other medical decision on information obtained from the RPCT and you agree to be solely responsible for, and to indemnify BTS and hold BTS harmless against, any loss or damage arising from any such decision.

Please confirm that you accept the conditions of use for this tool by checking this box:

Please select a calculation model:

Brock Model
Herder Model
Volume Doubling Time

Probability of malignancy following CT (Brock Model)

Patient Characteristics

Nodule Characteristics

Brock Model Probability:

The Brock model This calculator estimates the probability that a lung nodule described above will be diagnosed as cancer within a two to four year follow up period. McWilliams A, Tammemagi MC, Mayo JR, et. al. Probability of cancer in pulmonary nodules detected on first screening CT. N Engl J Med. 2013 Sep 5;369(10):910-9. doi:10.1056/NEJMoa1214726

Probability of malignancy following PET-CT (Herder Model)

Patient Characteristics

Nodule Characteristics

Herder Model Probability:

* Classification of FDG:

No FDG avidity = Uptake indiscernible from background lung tissue
Faint = Uptake less than or equal to mediastinal blood pool
Moderate = Uptake greater than mediastinal blood pool
Intense = Uptake markedly greater than mediastinal blood pool.

Note that the original model asks if there is a history of extra-thoracic malignancy ≥5 years previously. Patients with more recent diagnoses were excluded from the model. However, validation studies have shown similar accuracy in a population including people with a history of more recent extra-thoracic cancer (see full guideline). Hence any history of extra-thoracic cancer should be entered as 'yes'.

The Herder model This calculator estimates the probability that a lung nodule described above will be diagnosed as cancer Herder GJ, van Tinteren H, Golding RP, Kostense PJ, Comans EF, Smit EF, Hoekstra OS. Clinical prediction model to characterize pulmonary nodules: validation and added value of 18F-fluorodeoxyglucose positron emission tomography. Chest: 2005 Oct;128(4):2490-6.

Volume Doubling Time

Nodule Characteristics

Volume Doubling Time: