Correction: Gamma Knife radiosurgery for vestibular schwannomas: Evaluation of planning using the sphericity degree of the target volume

by Crystian Wilian Chagas Saraiva, Simone Coutinho Cardoso, Daniela Piai Groppo, Antônio Afonso Ferreira De Salles, Luiz Fernando de Ávila, Luiz Antonio Ribeiro da Rosa