ESTRO 36 Abstract Book

S38 ESTRO 36 _______________________________________________________________________________________________

In the standard group, the considered trigger point percentages were 1.3 for neck, 13.8 for trapezium, 13.8 for scapula, 16.5 for pectoral muscle, 11.3 for arm and 5 for dorsal spine. The corresponding values of the hypofractionated group were respectively 6.5, 29, 19.4, 6.5, 12.9, 6.5%. Results are summarized in table 1.

apply abdominal compression force. Indexing numbers on the adjustable screw indicated the pressure that was applying to the volunteers. Four sets of MRI scans with four levels of abdominal compression were performed on each volunteer including, (i) free breathing (FB) representing no abdominal compression force applied (screw just touching pressure plate), (ii) high abdominal compression (HAC) representing the maximum abdominal compression force which the volunteer could tolerate, (iii) medium abdominal compression (MAC) representing 80% of HAC (80% of the screw reading difference between FB and HAC), (iv) low abdominal compression (LAC) representing 50% of HAC (50% of the screw reading difference between FB and HAC) . Examinations were done in a MR-Simulator (Siemens MAGNETOM RT Pro edition). Two six-channel radiofrequency coils were used to cover thorax and abdomen regions. A setup photo is shown in Fig.1. One dynamic MRI image (trueFISP sequence) was obtained at mid-coronal plane. The total acquisition time was about 14 seconds in a speed of 3 frames/s. The MR scan was repeated under the conditions of FB, HAC, MAC and LAC. Maximum diaphragm displacements were defined as the differences between the most superior and the most inferior diaphragm dome position in the dynamic MRI images. Maximum diaphragm displacements were compared among FB, HAC, MAC and LAC to investigate the effectiveness of abdominal compression on diaphragm motion control.

Conclusion According to DASH score and trigger point evaluation, a better ROM can be appreciated in patients who underwent standard RT. Pain is more common, both in terms of intensity and trigger point frequency (scapula and trapezium on top), in patients who underwent hypofractionated treatment. A slight arm functional impairment can also be recognized in this group. These not statistically significant observations need to be further validated in more homogeneous and numerous samples in order to define an effective rehabilitation program. OC-0074 Analysis of diaphragm motion at various levels of abdominal compression by dynamic MRI K.F. Cheng 1 , P.H. Fok 1 , J. Yuan 2 , O.L. Wong 2 , G. Chiu 1 1 Hong Kong Sanatorium & Hospital, D epartment of Radiotherapy, Happy Valley, Hong Kong SAR China 2 Hong Kong Sanatorium & Hospital, Medical Physics and Research Department, Happy Valley, Hong Kong SAR China Purpose or Objective To investigate the effectiveness of abdominal compression on diaphragm motion control. Material and Methods 15 healthy volunteers were recruited. Volunteers were positioned in Orfit stereotactic body radiation therapy (SBRT) solution which included a short SBRT base plate, a pressure system bridge, an adjustable screw and a pressure plate. The pressure plate was placed on the abdomen inferiorly to xiphoid process and rib cage to

Results One-way ANOVA was used to test the mean differences of maximum diaphragm displacement among the groups and the results are shown in table 1. The superior-inferior (SI) motion of diaphragm was decreased with increasing abdominal compression force. The mean of maximum right diaphragm displacement had significant differences in comparisons of HAC vs LAC, HAC vs FB, MAC vs FB (All p <0.05). Significant mean difference of maximum left diaphragm displacement was found in HAC vs. FB ( p <0.05). The mean of maximum diaphragm displacement of right and left diaphragm was significantly reduced from 14.23 mm to 10.59 mm and from 13.64 mm to 10.34 mm respectively. 80% volunteers had less right diaphragm SI motion under HAC than FB. 73.3% volunteers had less left diaphragm SI motion under HAC than FB.

Conclusion The performance of SBRT pressure bridge system is positive in reducing the diaphragm motion. However, because not all volunteers had reduced diaphragm motion under abdominal compression, screening is suggested for using the device to ensure patient can be benefited from it.