Effect of different patient positions on target dose coverage in rectal cancer IMRT / 中华放射肿瘤学杂志

Objective To compare the effect between the supine and prone patient positions upon target dose coverage during intensity-modulated radiotherapy (IMRT) for rectal cancer, aiming to provide clinical reference for the selection of position for rectal cancer patients. Methods Twenty-four patients diagnosed with rectal cancer receiving postoperative adjuvant radiotherapy were selected and divided into the supine (n=12) and prone position groups(n=12). Before and during the IMRT(1-4 weeks),all patients received CT scans, which were defined as:Plan,1W,2W,3W and 4W,respectively. The organs at risk were delineated based on CT scan images. Plan,1W, 2W, 3W and 4W CT scan images were fused. The CTV and PTV from Plan CT scan were copied to the 1-4W CT scan images,and the therapeutic plans from Plan CT scan were copied as well. The target dose coverage was assessed and the failure rate of target dose coverage was calculated. The couch-position data for each patient during each cycle of IMRT were recorded by using the MOSAIQ network and the overall deviation (S) of couch position was calculated. Results The failure rates of CTV and PTV target dose coverage in the prone position group were higher than those in the supine position group (18.60% VS 0%, 69.76% VS 53.65%).The S value was significantly correlated with the target dose coverage (r=-0.683,P=0.000). The S value in the prone position group was(1.23±0.76) cm,significantly greater than(0.28±0.18) cm in the supine position (P=0.001),and the most significant deviation was noted in the y (head and foot) and z (frontal and dorsal) directions (P=0.003 and 0.003). Compared with the supine group,the V5and V10 of the small intestine were significantly less (P=0.003 and 0.004) and the chronic toxicity (NTCPC) was considerably reduced(P=0.041) in the prone position group. Conclusions A better target dose coverage can be maintained during IMRT with a supine position during rectal cancer IMRT, whereas the positioning repeatability is worsened with a prone position due to use of the belly board, thereby affecting the target dose coverage. Although the prone position combined with belly board can reduce the tolerated dosage of the small intestine,effective measures should be taken to guarantee the patient positioning repeatability.

Morphologic change of rectosigmoid colon using belly board and distended bladder protocol

PURPOSE: This study investigates morphologic change of the rectosigmoid colon using a belly board in prone position and distended bladder in patients with rectal cancer. We evaluate the possibility of excluding the proximal margin of anastomosis from the radiation field by straightening the rectosigmoid colon. MATERIALS AND METHODS: Nineteen patients who received preoperative radiotherapy between 2006 and 2009 underwent simulation in a prone position (group A). These patients were compared to 19 patients treated using a belly board in prone position and a distended bladder protocol (group B). Rectosigmoid colon in the pelvic cavity was delineated on planning computed tomography (CT) images. A total dose of 45 Gy was planned for the whole pelvic field with superior margin of the sacral promontory. The volume and redundancy of rectosigmoid colon was assessed. RESULTS: Patients in group B had straighter rectosigmoid colons than those in group A (no redundancy; group A vs. group B, 10% vs. 42%; p = 0.03). The volume of rectosigmoid colon in the radiation field was significantly larger in group A (56.7 vs. 49.1 mL; p = 0.009). In dose volume histogram analysis, the mean irradiated volume was lower in patients in group B (V45 27.2 vs. 18.2 mL; p = 0.004). In Pearson correlation coefficient analysis, the in-field volume of rectosigmoid colon was significantly correlated with the bladder volume (R = 0.86, p = 0.003). CONCLUSION: Use of a belly board and distended bladder protocol could contribute to exclusion of the proximal margin of anastomosis from the radiation field.

Morphologic change of rectosigmoid colon using belly board and distended bladder protocol

PURPOSE: This study investigates morphologic change of the rectosigmoid colon using a belly board in prone position and distended bladder in patients with rectal cancer. We evaluate the possibility of excluding the proximal margin of anastomosis from the radiation field by straightening the rectosigmoid colon. MATERIALS AND METHODS: Nineteen patients who received preoperative radiotherapy between 2006 and 2009 underwent simulation in a prone position (group A). These patients were compared to 19 patients treated using a belly board in prone position and a distended bladder protocol (group B). Rectosigmoid colon in the pelvic cavity was delineated on planning computed tomography (CT) images. A total dose of 45 Gy was planned for the whole pelvic field with superior margin of the sacral promontory. The volume and redundancy of rectosigmoid colon was assessed. RESULTS: Patients in group B had straighter rectosigmoid colons than those in group A (no redundancy; group A vs. group B, 10% vs. 42%; p = 0.03). The volume of rectosigmoid colon in the radiation field was significantly larger in group A (56.7 vs. 49.1 mL; p = 0.009). In dose volume histogram analysis, the mean irradiated volume was lower in patients in group B (V45 27.2 vs. 18.2 mL; p = 0.004). In Pearson correlation coefficient analysis, the in-field volume of rectosigmoid colon was significantly correlated with the bladder volume (R = 0.86, p = 0.003). CONCLUSION: Use of a belly board and distended bladder protocol could contribute to exclusion of the proximal margin of anastomosis from the radiation field.

Influence of laser positioning system to position repeatability in the use of improved belly board / 肿瘤研究与临床

Objective To investigate influence of laser positioning system to position repeatability of patients treated with radiotherapy for pelvic tumors.Methods Forty patients with pelvic tumors were divided into two groups,using laser positioning system positioning (20 cases) and conventional positioning (20 cases),respectively,CBCT was used to verify and analyze the setup errors of two groups.Results The setup errors on X,Y and Z axes in laser positioning system positioning group were (2.63±1.07) mm,(2.38±1.28) mm and (2.46±1.21) mm,they were (3.04±1.22) mm,(2.55±1.35) mm and (3.09±1.37) mm in conventional positioning group.It has significance reduce on X and Z axes (P =0.040,0.003,respectively) by using laser positioning system,and has no significance on Y axis (P =0.432).Conclusion It can improve patient positioning repeatability effectively by using laser positioning system for patient positioning.

Application of improved belly board in postoperative patients of rectal cancer radiotherapy / 肿瘤研究与临床

Objective To evaluate the application of improved belly board in postoperative patients of rectal cancer radiotherapy and explore the influence of its set-up repeatability.Methods CBCT was used to measure the intra fractional and inter fractional setup errors using normal or improved belly board respectively.The data was analyzed with statistic method.Results There was no significance of intra fractional setup errors on x-axis (P ＞ 0.05).There was significance on y and z-axis (P ＜ 0.05).There was no significance of interfrational setup errors on x-axis (P ＞ 0.05) and there was significance on y and z-axis (P ＜ 0.05) using normal belly board.There was no significance of intrafractional setup errors on x,y and z-axis (P ＞ 0.05).There was also no significance of interfractional setup errors on x,y and z-axis (P ＞ 0.05) with using improved belly board.Conclusion The method of improved belly board has more advantage than nomal belly board in controlling set-up repeatability,and it is conductive to improve accuracy of patients treatment.

The Efficacy of the Change in Belly Board Aperture Location by the Addition of Bladder Compression Device for Radiotherapy of Rectal Cancer / 대한방사선종양학회지

PURPOSE: We investigated the effect of location changes in the inferior border of the belly board (BB) aperture by adding a bladder compression device (BCD). MATERIALS AND METHODS: We respectively reviewed data from 10 rectal cancer patients with a median age 64 years (range, 45~75) and who underwent computed tomography (CT) simulation with the use of BB to receive pelvic radiotherapy between May and September 2010. A CT simulation was again performed with the addition of BCD since small bowel (SB) within the irradiated volume limited boost irradiation of 5.4 Gy using the cone down technique after 45 Gy. The addition of BCD made the inferior border of BB move from symphysis pubis to the lumbosacral junction (LSJ). RESULTS: Following the addition of BCD, the irradiated volumes of SB and the abdominopelvic cavity (APC) significantly decreased (174.3+/-89.5 mL vs. 373.3+/-145.0 mL, p=0.001, 1282.6+/-218.7 mL vs. 1571.9+/-158 mL, p<0.001, respectively). Bladder volume within the treated volume increased with BCD (222.9+/-117.9 mL vs. 153.7+/-95.5 mL, p<0.001). The ratio of irradiated bladder volume to APC volume with BCD (33.5+/-14.7%) increased considerably compared to patients without a BCD (27.5+/-13.1%) (p<0.001), and the ratio of irradiated SB to APC volume decreased significantly with BCD (13.9+/-7.6% vs. 24.2+/-10.2%, p<0.001). The ratios of the irradiated SB volumeand irradiated bladder volume to APC volume negatively correlated (p=0.001). CONCLUSION: This study demonstrated that the addition of BCD, which made the inferior border of BB move up to the LSJ, increased the ratio of the bladder to APC volume and as a result, decreased the irradiated volume of SB.

Influence of belly board device and the distended bladder on dosimetric analysis and normal tissue complication in postoperative radiation therapy of rectal cancer / 中华放射医学与防护杂志

Objective To evaluate the influence of belly beard device and the distended bladder on the dose distribution of PTV and the dose-volume histograms(DVHs)of organs at risk(OARs)for postoperative radiation tIlerapy of rectal cancer.Methods A total of 23 patients(8 and 15)with distended bladder receiving 3-field postoperative radiation therapy were dealed with or without a special belly beard in the prone position.At the same time,15 cages with belly board were scanned with empty bladder.The volume of irradiated small bowel was calculated for doses between 5-50 Gy at 5 Gy intervals.With prescription dose in plan target volume(PTV)of 50 Gy,we compared the dose distribution,DVH of OARs,conformity index(CIPTV),the volume of irradiated small bowel and the acute toxicity under the condition of thlee different moulds.Results There was no significant difference in PTV's converge,DVHs of femoral head and CI among 3 moulds(P＞0.05).With the belly board,the high-dose volume of irradiated small bowel(V20-V52.5)was significantly decreased(P＜0.05),specially with distended bladder.However,the low dose volume(V5-V15)was slightly increased.The bladder distension significanfly decreases the volumes of the irradiated small howel at dose levels from 15-52.5 Gy(P＜0.05).Furthermore,the mean volume(V5-V30)of irradiated small bowel differed significantly between patients experiencing Grade 0.1 and ≥2 diarrhea(P＜0.05).Conclusions The combination of belly board and distended bladder was more effectively to reduce the irradiated small bowel volume among 3 moulds,so as to minimized acute diarrhea toxicity.

The 3-Dimensional Analysis of the Efficacy of a Belly-Board Device for the Displacement of Small Bowel During Pelvic Irradiation / 대한방사선종양학회지

PURPOSE: To evaluate the efficacy of a belly-board device (BBD) in reducing the volume of small bowel during four-field pelvic irradiation. MATERIALS AND METHODS: Twenty-two cancer patients (14 uterine cervical cancer, 6 rectal cancer, and 2 endometrial cancer) scheduled to receive pelvic irradiation were selected for this study. Two sets of CT images were taken with and without the belly-board device using the Siemens 16 channel CT scanner. All patients were set in the prone position. The CT images were transferred to a treatment planning system for dose calculation and volume measurements. The external surfaces of small bowel and the bladder were contoured on all CT scans and the 4-pelvic fields were added. The dose-volume-histogram of the bladder and small bowel, with and without the BBD, were plotted and analyzed. RESULTS: In all patients, the total small bowel volume included in the irradiated fields was reduced when the BBD was used. The mean volume reduction was 35% (range, 1~79%) and was statistically significant (p<0.001). The reduction in small bowel volume receiving 10~100% of the prescribed dose was statistically significant when the BBD was used in all cases. Almost no change in the total bladder volume involved was observed in the field (<8 cc, p=0.762). However, the bladder volume receiving 90% of the prescribed dose was 100% in 15/22 patients (68%) and 90~99% in 7/22 patients (32%) with the BBD. In comparison, the bladder volume receiving 90% of the prescribed dose was 100% in 10/22 patients (45%), 90~99% in 7/22 patients (32%), and 80~89% in 5/22 patients (23%) without the BBD. When the BBD was used, an increase in the bladder volume receiving a high dose range was observed. CONCLUSION: This study shows that the use of a BBD for the treatment of cancer in the pelvic area significantly improves small bowel sparing. However, since the BBD pushed the bladder into the treatment field, the bladder volume receiving the high dose could increase. Therefore it is recommended to be considerate in using the BBD when bladder damage is of concern.

Effectiveness of Bellyboard Device for Displacement of Small Bowel in Pelvic Irradiation / 의학물리

Various techniques were evaluated to determine the best method for reducing small bowel involvement in pelvic irradiation. Fourteen patients receiving radiation in pelvic area were enrolled for this study. Five sets of small bowel images were obtained. Patients were positioned on a simulation couch with full bladder in prone and supine positions and 2 sets of images were taken. Then they were asked to empty their bladder and 2 sets of images were taken in prone and supine positions. A belly board device (BBD) was placed and one set of images was obtained. Using a software, the area of small bowel inside treatment field was contoured, measured, and analyzed. In both full and empty bladder cases, small bowel area reduction was observed in prone position as compared to supine position. Especially statistically significant reduction is noted in lateral film. An average decreases of 13% in PA and 26% in lateral direction were noted with bladder distention as compared to empty bladder. With the use of BBD for empty bladder, a significant reduction of 62.8+/-27.1% and 63.1+/-32.9% in PA and lateral directions were observed as compared to without BBD in prone position, respectively. In conclusion, the best sparing of small bowel concerning the area included in the treatment fields was achieved with BBD in prone position with empty bladder. However, further reduction is expected if the bladder was filled fully because the analysed data with empty vs full bladder study shows increased sparing of small bowel with distended bladder.