Abstract:Objective By studying the effect of Image Value to Density tables (IVDT) created by different brand density phantoms on
Tomotherapy dose calculation accuracy, to explore how to create IVDT correctly in a Tomotherapy planning system.
Methods The corresponding IVDT tables were established by Gammex and CIRS density models respectively. The IVDT tables
were created by whether there were density points of air and whether there were density points of substances other than water in
the range of CT value -100~100 HU. Four groups of intensity modulation plans were designed using different IVDT tables, and
seven groups of delivery quality assurance (DQA) were generated at the same time. Dose deviations of the 11 groups of intensity
modulation plans were measured and paired T test was performed to determine whether the IVDT table met the requirements.
Results In the IVDT table, the dose deviation of the -100~100 HU plan group was 1.55%±0.9%, which was statistically different
from that of the standard plan group (P<0.01). Similarly, the dose deviation of the group without air density point also showed
significant dosiological difference. There was no significant difference in the dose deviation of the 5 groups of DQA plan using CIRS
IVDT Abdo (-100~100 HU) and Gammex IVDT Abdo (Standard) in 7 groups (P>0.05). The mean dose deviation of DQA plan in
the two groups using CIRS IVDT Abdo (-100~100 HU) was 1.77%±1%, which was statistically different from that in the control
group. Conclusion When creating the IVDT table, it is necessary to ensure that CT values within the range of -100~100 HU do not
contain any density points of other substances except water, and air density points should be added into the curve, which have a great
influence on the accuracy of dose calculation.
庞廷田,杨波,于浪,刘峡,刘楠,李文博,董婷婷,邱杰. Tomotherapy计划系统中利用不同密度模体精确创建CT值密度曲线[J]. 中国医疗设备, 2022, 37(2): 29-34.
PANG Tingtian, YANG Bo, YU Lang, LIU Xia, LIU Nan, LI Wenbo, DONG Tingting, QIU Jie. Method of Creating Image Value to Density Table by Different Brand Density Phantoms in
Tomotherapy Treatment Planning System. China Medical Devices, 2022, 37(2): 29-34.