In HET, high-precision course of radiotherapy, generally used for treatments where lesions are small or very close to critical structures or organs. The course of a SRT treatment may be hypofractionated, with treatment delivered in 3 to 7 fractions (high dose/fraction). This can be compared to a conventional radiotherapy course of treatment where treatment is delivered over 30 to 35 fractions (low dose/fraction). Some new SRT techniques escalate the dose relative to a conventional fractionated treatment. SRT requires precise positioning of the patient and immobilization, and then monitoring during treatment delivery.