A2) Compensation techniques Methods that reduce respiration induced intrafraction motion include active breathing control, voluntary breath-hold, deep inspiration breath-hold, respiratory gated techniques, and 4D or tumor-tracking techniques.1-6 Active breathing control and the deep inspiration breath hold involves the patient holding their breath. While these may improve the reproducibility of the position of the tumor within the lung, it is not feasible for all patients especially those that have a compromised respiratory function. Respiratory gating techniques involves turning on the beam during only a small window of the respiratory cycle. Thus respiratory gating reduces the intrafraction motion but does not totally eliminate it. During respiratory gating, since the beam is turned on and off based on the respiration signal, the treatment time may increase up to 35-40% compared to a regular treatment. Since the patient has to spend more time on the table, this could introduce more errors due to patient movement on the table. 4D or tumor tracking techniques has it own share of issues as is discussed in the following paragraph.