Three parts of the device. (a) Support arm to fix a device on the treatment couch. (b) This part is used to match the device to the center of the digital radiography system. (c) Instrument used to affix a film or IP.
Schematic diagram of our new device. Dash line is crossed to multiple shows the slit proton beam. While (b) cannot essentially be divided apart, the figure shows to make it easy to see. Figure is not shown four pairs of magnet to attach the (b) and (c).
Internal construction of Fig. 2(b). The position of the center steel ball is indicated by the black dashed arrow. The four magnets used for fixation are indicated by black arrows.
Cross line of a cardinal angle is indicated by the black arrows.
Internal construction of Fig. 1(c). The four magnets are indicated by black arrows.
First set-up step is matching the room laser to the cross line on the frame. The device is view from lateral.
Second set-up step is matching the steel ball to the image center of the digital radiography system.
Patient collimator for producing a 2 mm slit proton beam.
Two patterns of irradiation angles. We performed the star-shots method using these angles. (a) Conditions for CW angles. (b) Conditions for CCW angles.
Analysis of the results for the star-shots method. Blue cross indicates the center of the rotational gantry. Red cross indicates the center of the digital radiography system define by the pin mark in the second step described. Sky blue dashed lines indicate each beam axis.
Measurement results for the differences between the rotational gantry and the digital radiography system isocenters over five weeks.
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