Global radiology leader Harrison.ai launched Harrison.Rad 1.5, a radiology foundation model that can reason over images and clinical context, including priors, to produce a high-quality draft report for review by a radiologist. Available immediately for research at chat.harrison.ai and API access on request, Harrison.Rad 1.5 is the only AI model to pass the FRCR 2B Short Case exam, the standard used to certify UK radiologists, while every radiology-specific and frontier model evaluated falls short.

Harrison.Rad 1.5 advances the program Harrison.ai began with Harrison.Rad 1 in 2024, which established the company as a leader in domain-specific foundation models for radiology. The new release widens that lead: stronger reasoning across complex, multi-finding studies, sharper anatomical localisation, broader coverage across body parts, and, most significantly, the ability to read a current study against a prior and describe what has changed in natural radiologist prose rather than a checklist of flagged findings.

That draft-reporting capability is the centre of gravity for the release. Rather than detecting findings in isolation, Harrison.Rad 1.5 can interpret a study in light of the clinical question being asked and the patient's history, then it can draft a report intended to give the radiologist something precise to work from.

"You can't skip steps in radiology AI. Before an AI model can help generate a report, it has to be excellent at detection, and that’s what we’ve been tirelessly working on over the past 8 years. Our regulatory-approved detection products for chest X-rays, Brain CTs and Chest CTs are being used every day, impacting more than a million patients per month. Harrison.Rad 1.5 is the next step towards bringing meaningful innovation forward that will impact the future practice of radiology," said Dr. Aengus Tran, CEO and co-founder of Harrison.ai. "Reporting is where radiologists spend their time. The future is where our Harrison.Rad foundation model drafts a high-quality report for the radiologist to review and sign off, without replacing their judgement."

To measure that progress, Harrison.ai evaluated Harrison.Rad 1.5 and other frontier models on an exam that human radiologists take, using externally sourced data not seen during training. On the FRCR 2B Short Case, the standard the Royal College of Radiologists adopted in 2025, in place of the now-retired Rapids format, Harrison.Rad 1.5 Agent achieved a median score of 86.5, above the mean cut-off of 73.2 needed to pass. No other evaluated models passed this exam.

On the older FRCR 2B Rapids exam, where Harrison.Rad 1 already led the field, Harrison.Rad 1.5 Core passed 24.3 per cent of full exam sheets, a 2.4x improvement from Harrison.Rad 1.

"General-purpose models like Anthropic’s Opus and OpenAI’s GPT-5 cannot pass an exam that qualifies a radiologist to practice. Harrison.Rad 1.5 can," said Dr. Jarrel Seah, Neuroradiologist and Chief Medical and AI Officer at Harrison.ai. "It was trained on 6 million diagnostic studies and 18 million clinically crafted conversations. The gains show up most clearly on the hardest cases: studies with priors, post-procedural work, and findings outside the classical reporting ontology. Eighteen months on from Harrison.Rad 1, the gap between our purpose-built model and the world's leading general-purpose models hasn't closed; it's widened. Clinical radiology demands a level of specificity that only comes from purpose-built training."