Temporal Volume Of Lung Tumor During Treatment With Tomotherapy

Purpose/Objective(s)The temporal change in volume during radiotherapy has become an increasingly important factor during the last years with the clinical introduction of image guided radiotherapy. The volume change of the tumor is of significant interest for eventual replanning of dose fields in response to volume reduction. If it is possible to predict volume evolution it might be possible to adapt dose plans accordingly to adjust dose fields to spare healthy tissue.Materials/MethodsThe material consisted of MVCT images from 13 lung patients treated with Tomotherapy©. For each patient the following scans were available: a kvCT scan used for planning recorded 9 - 5 days before first treatment session and MVCT images recorded prior to every treatment session The 6 of the patients had received 5 times 3 fractions, short treatment group, and the remaining 7 patients had received up to 32 times 1 fraction, long treatment group. The volume of 15 tumors was segmented on 226 scans. The visible tumor volume on the CT's was segmented automatically by a novel method using the contour on the original scan and finding the corresponding locations on the following scans. The method takes account to the partial volume effect. The relative and absolute volume difference between the scan at treatment 1 and 5 between the two treatment groups was tested using a t-test. The correlation between initial volume and volume reduction was tested for all patients at treatment 5 using Pearson's correlation coefficient. Correlations between volumes at treatment 5 and final treatment for both relative and absolute difference from initial volume was tested using Pearson's correlation coefficient.ResultsTumor volumes were successfully segmented on all scans. The absolute and relative volume difference was not significantly different between the short treatment group and the long treatment group at treatment 5, respectively p = 0.08 and r = 0.83 There was a significant correlation, p = 0.01 and r = -0.76, between initial volume and absolute volume difference at treatment 5 whereas relative volume difference showed no significant correlation, p = 0.81. For the patients receiving a long treatment there was a significant correlation between relative and absolute volume difference at treatment 5 and at the final treatment, p = 0.04 and r = 0.75, and the absolute difference showed no significance, p = 0.06.ConclusionsA novel method was used to segment visible and partial lung tumor volume during treatment on a total of 226 scans. A significant negative correlation was found between initial tumor volume and volume at treatment 6: large tumors had larger decrease in volume. A significant positive correlation between early and late volume response opens up a possibility of early treatment response prediction. Purpose/Objective(s)The temporal change in volume during radiotherapy has become an increasingly important factor during the last years with the clinical introduction of image guided radiotherapy. The volume change of the tumor is of significant interest for eventual replanning of dose fields in response to volume reduction. If it is possible to predict volume evolution it might be possible to adapt dose plans accordingly to adjust dose fields to spare healthy tissue. The temporal change in volume during radiotherapy has become an increasingly important factor during the last years with the clinical introduction of image guided radiotherapy. The volume change of the tumor is of significant interest for eventual replanning of dose fields in response to volume reduction. If it is possible to predict volume evolution it might be possible to adapt dose plans accordingly to adjust dose fields to spare healthy tissue. Materials/MethodsThe material consisted of MVCT images from 13 lung patients treated with Tomotherapy©. For each patient the following scans were available: a kvCT scan used for planning recorded 9 - 5 days before first treatment session and MVCT images recorded prior to every treatment session The 6 of the patients had received 5 times 3 fractions, short treatment group, and the remaining 7 patients had received up to 32 times 1 fraction, long treatment group. The volume of 15 tumors was segmented on 226 scans. The visible tumor volume on the CT's was segmented automatically by a novel method using the contour on the original scan and finding the corresponding locations on the following scans. The method takes account to the partial volume effect. The relative and absolute volume difference between the scan at treatment 1 and 5 between the two treatment groups was tested using a t-test. The correlation between initial volume and volume reduction was tested for all patients at treatment 5 using Pearson's correlation coefficient. Correlations between volumes at treatment 5 and final treatment for both relative and absolute difference from initial volume was tested using Pearson's correlation coefficient. The material consisted of MVCT images from 13 lung patients treated with Tomotherapy©. For each patient the following scans were available: a kvCT scan used for planning recorded 9 - 5 days before first treatment session and MVCT images recorded prior to every treatment session The 6 of the patients had received 5 times 3 fractions, short treatment group, and the remaining 7 patients had received up to 32 times 1 fraction, long treatment group. The volume of 15 tumors was segmented on 226 scans. The visible tumor volume on the CT's was segmented automatically by a novel method using the contour on the original scan and finding the corresponding locations on the following scans. The method takes account to the partial volume effect. The relative and absolute volume difference between the scan at treatment 1 and 5 between the two treatment groups was tested using a t-test. The correlation between initial volume and volume reduction was tested for all patients at treatment 5 using Pearson's correlation coefficient. Correlations between volumes at treatment 5 and final treatment for both relative and absolute difference from initial volume was tested using Pearson's correlation coefficient. ResultsTumor volumes were successfully segmented on all scans. The absolute and relative volume difference was not significantly different between the short treatment group and the long treatment group at treatment 5, respectively p = 0.08 and r = 0.83 There was a significant correlation, p = 0.01 and r = -0.76, between initial volume and absolute volume difference at treatment 5 whereas relative volume difference showed no significant correlation, p = 0.81. For the patients receiving a long treatment there was a significant correlation between relative and absolute volume difference at treatment 5 and at the final treatment, p = 0.04 and r = 0.75, and the absolute difference showed no significance, p = 0.06. Tumor volumes were successfully segmented on all scans. The absolute and relative volume difference was not significantly different between the short treatment group and the long treatment group at treatment 5, respectively p = 0.08 and r = 0.83 There was a significant correlation, p = 0.01 and r = -0.76, between initial volume and absolute volume difference at treatment 5 whereas relative volume difference showed no significant correlation, p = 0.81. For the patients receiving a long treatment there was a significant correlation between relative and absolute volume difference at treatment 5 and at the final treatment, p = 0.04 and r = 0.75, and the absolute difference showed no significance, p = 0.06. ConclusionsA novel method was used to segment visible and partial lung tumor volume during treatment on a total of 226 scans. A significant negative correlation was found between initial tumor volume and volume at treatment 6: large tumors had larger decrease in volume. A significant positive correlation between early and late volume response opens up a possibility of early treatment response prediction. A novel method was used to segment visible and partial lung tumor volume during treatment on a total of 226 scans. A significant negative correlation was found between initial tumor volume and volume at treatment 6: large tumors had larger decrease in volume. A significant positive correlation between early and late volume response opens up a possibility of early treatment response prediction.