A method of preventing damage to non-neoplastic, e.g. healthy cells, by irradiating the non-neoplastic cells with a low-dose radiation is provided. The method initiates a protective cellular response which prevents later damage to non-neoplastic cells by radiotherapy and an immune response against neoplastic cells. The method of preventing damage to non-neoplastic cells is provided where the low-dose radiation is interspersed with a high dose sessions which themselves are varied through the weekly schedule.