Read the following statements regarding the various techniques used in cancer detection.
(i) Cancer detection is based on biopsy and histopathological studies of the tissue, and blood and bone marrow tests for increased cell counts in case of leukaemia.
(ii) In biopsy, a piece of the suspected tissue cut into thin sections is stained and examined under microscope by a pathologist.
(iii) Techniques like radiography (use of $\mathrm{X}$ -rays), CT (computed tomography) and MRI (magnetic resonance imaging) are very useful to detect cancers of the internal organs.
(iv) Computed tomography uses strong magnetic fields and non-ionising radiations to detect physiological changes in living tissues.
(v) MRI uses X-rays and ionising radiation to generate a $3-\mathrm{D}$ image of the internal structure of an object.
Which of the above statements are incorrect?