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. 2013 Oct 23;40(11):111917. doi: 10.1118/1.4826159

Figure 8.

Figure 8

Air KERMA and number of beamlets with changing patient location while maintaining tumor SNR on the SBDX. (a) The air KERMA at the detector (if the patient were absent) necessary for maintaining SNR at multiple patient locations while collimating down the beams to various distances around the tumor. The beam collimation measurements represent a square (with a length of our measurement) in the plane of the tumor outside of which beamlets are removed. (b) the number of beamlets which contribute to tumor signal and the number of beamlets used when different collimator sizes are used. The dashed lines represent the number of beamlets necessary for the trend to continue if our collimator had more than 10 000 beamlets. These simulations used a SDD of 110 cm.