Iterative methods for inverse treatment planning.

Iterative algorithms used in imaging science are generalized to study inverse treatment planning in radiotherapy. These algorithms consist of iteratively changing trial incident fluence functions which eventually yield a dose distribution consistent with the prescribed distribution. Application of the algorithms is presented for test cases of a circular phantom with cylindrically symmetric dose distributions. A comparison of the iterative beam profiles with previous analytic solutions shows excellent agreement, indicating that iterative techniques are promising to create sophisticated treatment plans. The relationship between the algorithms and several existing inverse treatment planning methods is discussed.