Randomization is based on a table of random numbers. First ,we prepare a random list as follows:. 3lesions will be choosen in every patients, for the three modalities, we will have following conditions:
1) Lesion 1treatment N, lesion 2 treatment NF, lesion 3control.
2) Lesion 1 treatment NF, lesion 2 treatment N, lesion 3 control
3) Lesion 1control, lesion 2 treatment N, lesion 3treatment NF
4) Lesion 1control, lesion 2treatment NF, lesion 3treatment N
5) Lesion 1treatment N, lesion 2control, lesion 3 treatment NF
6) Lesion 1treatment NF, lesion 2control, lesion 3 treatment N
Each of these arrangements is placed in a sealed envelope. Then, based on the table of random numbers, the envelopes are given to patients. We begin from a point in table of random numbers and write the numbers and ignore numbers greater than 6 , continue to reach the desired sample size . Give every patient the determined envelope.
For example consider the numbers from the table: 5179483
First patient envelope 5 , secound patient envelope 1, ignore the 7and 9 , third patient envelope 4 and ....