Clinical calculators
58 evidence-based tools — dose, contrast, oncology, neuro, cardiac & more
☢️Radiation Safety (2)
Radiation Dose Calculator (DLP to Effective Dose)
Convert CT Dose Length Product (DLP) to effective dose (mSv) for patient counseling and dose tracking. Essential for ALARA principles.
Pediatric CT Dose Adjustment
Calculate appropriate CT dose reduction for pediatric patients based on age and weight. Prevent unnecessary radiation exposure.
💉Contrast Safety (2)
eGFR Calculator (Contrast Safety)
Calculate estimated Glomerular Filtration Rate to assess renal function before IV contrast administration. Prevent contrast-induced nephropathy.
Contrast Dose Calculator (Body Weight)
Calculate appropriate iodinated contrast volume based on patient weight and concentration. Optimize image quality while minimizing risk.
🤰Obstetric Imaging (6)
Pregnancy Dating (Ultrasound Biometry)
Calculate gestational age and estimated delivery date from ultrasound measurements. Critical for African maternal health.
Estimated Fetal Weight (EFW)
Estimate fetal weight from ultrasound biometry. Detect IUGR and macrosomia. Essential for delivery planning.
Early Pregnancy Discriminatory Values
Applies mean sac diameter and serum β-hCG discriminatory thresholds to distinguish a normal early intrauterine pregnancy from a non-diagnostic scan or a failed / ectopic pregnancy.
Amniotic Fluid Index (AFI)
Categorises amniotic fluid volume from the four-quadrant amniotic fluid index to identify oligohydramnios or polyhydramnios.
Nuchal Translucency (NT)
Interprets first-trimester nuchal translucency thickness and confirms measurement validity against the crown-rump length window.
Cervical Length & Preterm Risk
Stratifies mid-trimester spontaneous preterm birth risk from transvaginal cervical length, accounting for singleton versus multiple gestation.
🚨Emergency Imaging (2)
CT Head Injury Decision Rule
Canadian CT Head Rule: Determine need for head CT in minor head injury. Reduce unnecessary radiation in African emergency departments.
Pulmonary Embolism Severity Index (PESI)
Risk stratify patients with PE to guide disposition. Low-risk PE may avoid admission in resource-limited settings.
🧠Clinical Decision Support (1)
🎗️Breast Imaging (1)
🧠Neuroradiology (8)
ICH Volume (ABC/2)
Rapid bedside estimate of intracerebral haemorrhage volume from three orthogonal CT measurements.
NASCET Carotid Stenosis
Percent internal carotid artery stenosis by the NASCET method used to guide carotid revascularisation.
Evans Index
Ratio of frontal horn width to maximal skull diameter, screening for ventriculomegaly and hydrocephalus.
Modified Fisher Scale
CT-based grading of subarachnoid haemorrhage that stratifies the risk of symptomatic vasospasm.
Hunt and Hess Grade
Clinical grading of aneurysmal subarachnoid haemorrhage severity, correlating with surgical risk and mortality.
ASPECTS
Alberta Stroke Program Early CT Score quantifying early ischaemic change in the MCA territory.
Fazekas Scale
Grading of white-matter hyperintensities on MRI, reflecting the burden of small-vessel disease.
Spetzler-Martin AVM Grade
Grading of brain arteriovenous malformations to predict the risk of surgical resection.
🫀Cardiothoracic (8)
Cardiothoracic Ratio (CTR)
Ratio of maximal cardiac width to maximal internal thoracic width on a frontal chest radiograph, screening for cardiomegaly.
Coronary Artery Calcium (Agatston)
Interpretation of the total Agatston coronary artery calcium score for cardiovascular risk stratification (MESA framework).
Pulmonary Artery : Aorta Ratio
Ratio of main pulmonary artery diameter to ascending aorta diameter on CT, a non-invasive marker of pulmonary hypertension.
RV/LV Diameter Ratio (CTPA)
Right-to-left ventricular short-axis diameter ratio on CT pulmonary angiography, a marker of right-heart strain in acute pulmonary embolism.
Ascending Aortic Diameter
Interpretation of ascending aortic diameter, with optional aortic size index (diameter indexed to body-surface area) to flag dilatation and surgical thresholds.
LV Mass (ASE Cube Formula)
Left ventricular mass from M-mode/2D linear dimensions using the ASE-recommended cube (Devereux) formula, for detection of left ventricular hypertrophy.
IVC Collapsibility → RA Pressure
Estimation of right atrial pressure from inferior vena cava diameter and its inspiratory collapse on echocardiography (ASE/Rudski criteria).
Pleural Effusion Volume Estimate
Approximate pleural effusion volume from the maximal pleural fluid separation measured on erect chest radiograph or thoracic ultrasound.
🩻Abdominal Imaging (3)
CT Adrenal Washout
Characterises an indeterminate adrenal nodule as a lipid-poor adenoma using absolute and relative contrast washout on multiphase CT.
Splenic Index
Estimates splenic volume from three orthogonal dimensions and flags splenomegaly.
Ellipsoid Volume
General-purpose ellipsoid volume for any lesion or organ from three orthogonal dimensions.
🫁Hepatobiliary (3)
Hepatic Steatosis (CT)
Estimates hepatic fat using absolute liver attenuation and the liver–spleen difference on non-contrast CT.
MELD-Na Score
Model for End-stage Liver Disease incorporating sodium, for chronic liver disease severity and transplant priority.
FIB-4 Index
Non-invasive index estimating hepatic fibrosis from age, transaminases and platelet count.
🫘Genitourinary (2)
🧮General (4)
Child-Pugh Score
Grades severity of chronic liver disease (cirrhosis) from bilirubin, albumin, INR, ascites and encephalopathy.
Body Surface Area (Mosteller)
Estimates body surface area from height and weight using the Mosteller formula.
Body Mass Index
Classifies weight status from height and weight using WHO body mass index bands.
Creatinine Clearance (Cockcroft-Gault)
Estimates creatinine clearance for renal function assessment and contrast/renal drug dosing.
🎯Oncologic Imaging (2)
🦴Musculoskeletal (4)
Genant Vertebral Grade
Semiquantitative grading of vertebral compression fracture from anterior, middle and posterior heights.
Cobb Angle
Grades scoliosis severity from the Cobb angle measured between the most tilted end vertebrae.
Böhler Angle (Calcaneus)
Assesses the tuber joint angle of the calcaneus on a lateral foot radiograph to detect depression of the posterior facet in calcaneal fractures.
Insall–Salvati Ratio (Patellar Height)
Quantifies patellar height on a lateral knee radiograph by comparing patellar tendon length with patellar bone length, detecting patella alta or baja.
🧮Endocrine Imaging (2)
Thyroid Volume (Ellipsoid)
Estimates single-lobe and total thyroid volume from ultrasound lobe dimensions using the ellipsoid formula, to grade goitre and guide radioiodine or surgical planning.
Adrenal Chemical-Shift (SII)
Quantifies signal drop between in-phase and opposed-phase MRI to characterise a lipid-rich adrenal adenoma using the adrenal signal intensity index.
🧮Gynaecologic Imaging (2)
Ovarian Volume (Ellipsoid)
Calculates ovarian volume from three ultrasound diameters using the prolate-ellipsoid formula to distinguish a normal ovary from an enlarged or postmenopausal ovary.
Endometrial Thickness
Interprets transvaginal endometrial thickness against menopausal status and bleeding history to decide whether tissue sampling is warranted.
🧮Vascular (3)
Ankle–Brachial Index (ABI)
Screens for peripheral arterial disease by comparing the higher ankle systolic pressure with the higher brachial systolic pressure.
Wells Score for Deep Vein Thrombosis
Estimates the clinical pretest probability of lower-limb deep vein thrombosis to guide D-dimer testing and compression ultrasound.
Carotid ICA/CCA PSV Ratio
Grades internal carotid artery stenosis on Doppler ultrasound by combining ICA peak systolic velocity with the ICA/CCA velocity ratio (SRU consensus).
🧮Chest Imaging (3)
Wells Score for Pulmonary Embolism
Estimates the clinical pretest probability of pulmonary embolism to guide use of D-dimer and CT pulmonary angiography.
Pulmonary Nodule Volume Doubling Time
Estimates the volume doubling time of a pulmonary nodule from two diameter measurements and the scan interval to help distinguish benign from malignant growth.
Aortic Size Index (ASI)
Normalises aortic diameter to body surface area to stratify the risk of rupture or dissection, complementing absolute diameter thresholds.
⚕️ All calculators are for educational and clinical decision support purposes.
Always verify calculations and apply clinical judgment.