Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Treatments (treatment_type_code VARCHAR)
TABLE: CREATE TABLE Treatment_types (treatment_type_description VARCHAR, treatment_type_code VARCHAR)

### Question ###
What is the description of the treatment type that costs the least money in total?

### Accurate SQL ###

SELECT T1.treatment_type_description FROM Treatment_types AS T1 JOIN Treatments AS T2 ON T1.treatment_type_code = T2.treatment_type_code GROUP BY T1.treatment_type_code ORDER BY SUM(cost_of_treatment) LIMIT 1