My daughter was treated with a high dose of radiation after they removed her thyroid and found cancer.

Jessica, I hope that every thing turns out alright for your daughter. It terms of taking legal action for the refusal to treat your daughter, it is impossible without much more information to assess whether or not a claim for damages could be made. Without any more information I cannot tell you if you should bring a claim or not. However, there are methods by which a member of the public can file a complaint against the facility alleging misconduct and seeking that the State sanction and / or correct the misconduct. This would not result in any monetary award to your daughter but it would result in an investigation of the incident by the state government, and if the facility did something wrong the state would document those facts. As with almost any situation of this sort, the best advice I can give is for you to gather all of the pertinent information you have access to and contact a good attorney in your area to discuss your options.