Question: when was radiotherapy first used to treat cancer
[{'answer': '1895', 'provenance': [{'wikipedia_id': '32469842', 'title': 'History of radiation therapy', 'start_paragraph_id': 1, 'start_character': 124, 'end_paragraph_id': 1, 'end_character': 128, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32469842', 'title': 'History of radiation therapy', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 711, 'bleu_score': 0.933792591768927, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9151918744770935378}, 'section': 'Section::::Abstract.'}]}]