| Research Abstract |
Using 10 pair of CT scan data set, one with ascitis and another without ascitis, the influence of ascitis on dose volume histogram of radiation therapy. Sham targets were set in liver, para-aortic lymph nodes, iliac lymph nodes, uterus, and prostate (2-4cm in diameter) and radiotherapy planning was done for each target using four box-field method. The margin from CTV was 1cm in all cases. As a result, 40 pair of radiotherapy plan (liver, para-aortic lymph node, iliac lymph node, and uterus or prostate) was made for each sham target and DVH of these plans were compared and analyzed with radiotherapy computer. Risk organ was defined as intestine and abdominal wall or diaphragm for upper abdominal tumor. For pelvic tumor, risk organs was defined as rectum and urinary bladder.
In all patients, the existence and volume of ascitis did not significantly influence dose or intestine, rectum, urinary bladder. However, in case of liver surface tumor radiation therapy, ascitis significantly reduce the dose for diaphragm and abdominal wall. In case of radiation therapy of liver tumor that is adjacent to intestine (under part of liver surface), ascitis was also expected to reduce the intestinal radiation dose.
In conclusion, liquid, injection into peritoneal space before radiation therapy for surface liver tumor seems to reduce toxicity. However, daily CT checking and positioning of patients is essential. Subtable for patients fixation and special stretcher to transport patients from CT table to linac table is very useful for this pourpose.
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