scholarly journals Evaluation of Small Bowel Motion and Feasibility of using the Peritoneal Space to Replace Bowel Loops for Dose Constraints during Intensity-Modulated Radiotherapy for Rectal Cancer

2020 ◽  
Author(s):  
Siyuan Li ◽  
Yanping Gong ◽  
Yongqiang Yang ◽  
Qi Guo ◽  
Jianjun Qian ◽  
...  
Keyword(s):  
Rectal Cancer ◽  
Small Bowel ◽  
Supine Position ◽  
Intensity Modulated Radiotherapy ◽  
Ct Scans ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Dose Constraint ◽  
Bowel Motion ◽  
Peritoneal Space

Abstract Background The goal of this study was to assess small bowel motion and explore the feasibility of using peritoneal space (PS) to replace bowel loops (BL) via the dose constraint method to spare the small bowel during intensity-modulated radiotherapy (IMRT) for rectal cancer. Methods A total of 24 patients with rectal cancer who underwent adjuvant radiotherapy were selected. Weekly repeat CT scans from pre-treatment to the fourth week of treatment were acquired and defined as Plan, 1W, 2W, 3W, and 4W. BL and PS contours were delineated in all of the scans. Two IMRT plans called P PS and P BL were designed on Plan CT using two dose PS and BL constraint methods, respectively, and then copied to CT 1~4W. The shift%, dose volume, and NTCP of the small bowel in P PS and P BL during treatment were evaluated. Results Overall, 109 sets of CT scans from 24 patients were acquired, and 218 plans were designed and copied. The PS and BL volumes were 1339.28 cc and 250.27 cc. The BL and PS shift% V 15 was 28.48% and 11.79% ( p =0.000), which was less in the prone position than in the supine position (25.24% vs 32.10%, p =0.000; 9.9% vs 14.85%, p =0.000). On all of the CT scans, most P PS small bowel dose volumes were less than from P BL . V 15 was 170.07 cc vs 178.58 cc ( p =0.000), and they had a significant correlation. The NTCP of chronic and acute side effects from P PS was significantly less than P BL (2.80% vs 3.00%, p =0.018; 57.32% vs 58.64%, p =0.000). Conclusions This study indicated that small bowel motion may lead to uncertainties in its dose volume and NTCP evaluation during IMRT for rectal cancer. The BL movements were significantly greater than PS, and the prone position was significantly less than the supine position. Using PS instead of BL can spare the small bowel. V 15 <830 cc is the dose constraint standard.

scholarly journals Evaluation of Small Bowel Motion and Feasibility of using the Peritoneal Space to Replace Bowel Loops for Dose Constraints during Intensity-Modulated Radiotherapy for Rectal Cancer

2020 ◽  
Author(s):  
Siyuan Li ◽  
Yanping Gong ◽  
Yongqiang Yang ◽  
Qi Guo ◽  
Jianjun Qian ◽  
...  
Keyword(s):  
Rectal Cancer ◽  
Small Bowel ◽  
Supine Position ◽  
Intensity Modulated Radiotherapy ◽  
Ct Scans ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Dose Constraint ◽  
Bowel Motion ◽  
Peritoneal Space

Abstract Background The goal of this study was to assess small bowel motion and explore the feasibility of using peritoneal space (PS) to replace bowel loops (BL) via the dose constraint method to spare the small bowel during intensity-modulated radiotherapy (IMRT) for rectal cancer. Methods A total of 24 patients with rectal cancer who underwent adjuvant radiotherapy were selected. Weekly repeat CT scans from pre-treatment to the fourth week of treatment were acquired and defined as Plan, 1W, 2W, 3W, and 4W. BL and PS contours were delineated in all of the scans. Two IMRT plans called PPS and PBL were designed on Plan CT using two dose PS and BL constraint methods, respectively, and then copied to CT 1 ~ 4W. The shift%, dose volume, and NTCP of the small bowel in PPS and PBL during treatment were evaluated. Results Overall, 109 sets of CT scans from 24 patients were acquired, and 218 plans were designed and copied. The PS and BL volumes were 1339.28 cc and 250.27 cc. The BL and PS shift% V15 was 28.48% and 11.79% (p = 0.000), which was less in the prone position than in the supine position (25.24% vs 32.10%, p = 0.000; 9.9% vs 14.85%, p = 0.000). On all of the CT scans, most PPS small bowel dose volumes were less than from PBL. V15 was 170.07 cc vs 178.58 cc (p = 0.000), and they had a significant correlation. The NTCP of chronic and acute side effects from PPS was significantly less than PBL (2.80% vs 3.00%, p = 0.018; 57.32% vs 58.64%, p = 0.000). Conclusions This study indicated that small bowel motion may lead to uncertainties in its dose volume and NTCP evaluation during IMRT for rectal cancer. The BL movements were significantly greater than PS, and the prone position was significantly less than the supine position. Using PS instead of BL can spare the small bowel. V15 < 830 cc is the dose constraint standard.

scholarly journals Evaluation of Small Bowel Motion and Feasibility of using the Peritoneal Space to Replace Bowel Loops for Dose Constraints during Intensity-Modulated Radiotherapy for Rectal Cancer

2020 ◽  
Author(s):  
Siyuan Li ◽  
Yanping Gong ◽  
Yongqiang Yang ◽  
Qi Guo ◽  
Jianjun Qian ◽  
...  
Keyword(s):  
Rectal Cancer ◽  
Small Bowel ◽  
Intensity Modulated Radiotherapy ◽  
Ct Scans ◽  
Dose Volume ◽  
Dose Constraint ◽  
Bowel Motion ◽  
Peritoneal Space ◽  
Pre Treatment ◽  
Constraint Method

Abstract Background: The goal of this study was to assess small bowel motion and explore the feasibility of using peritoneal space (PS) to replace bowel loops (BL) via the dose constraint method to spare the small bowel during intensity-modulated radiotherapy (IMRT) for rectal cancer. Methods: A total of 24 patients with rectal cancer who underwent adjuvant or neoadjuvant radiotherapy were selected. Weekly repeat CT scans from pre-treatment to the fourth week of treatment were acquired and defined as Plan, 1W, 2W, 3W, and 4W. The 4 weekly CT scans were co-registered to the Plan CT, BL and PS contours were delineated in all of the scans, an IMRT plan was designed on Plan CT using PS constraint method, and then copied to the 4 weekly CT scans. The dose-volume, normal tissue complication probability (NTCP) of the small bowel and their variations during treatment were evaluated. Results: Overall, 109 sets of CT scans from 24 patients were acquired, and 109 plans were designed and copied. The BL and PS volumes were 250.3 cc and 1339.3 cc. The V15 of BL and PS based plan of pre-treatment were 182.6 cc and 919.0 cc, the shift% of them were 28.9% and 11.3% during treatment (p=0.000), which was less in the prone position than in the supine position (25.2% vs 32.1%, p =0.000; 9.9% vs 14.9%, p=0.000). The NTCPC and NTCPA based plan of pre-treatment were 2.0% and 59.2%, the shift% during treatment were 46.1% and 14.0% respectively. Majority of BL’s Dmax and V15 were meet the safety standard during treatment using PS dose limit method except 3 times (3/109) of V15 and 5 times of Dmax (5/109).Conclusions: This study indicated that small bowel motion may lead to uncertainties in its dose volume and NTCP evaluation during IMRT for rectal cancer. The BL movements were significantly greater than PS, and the prone position was significantly less than the supine position. It is feasibility of using PS to replace BL to spare the small bowel, V15<830 cc is the dose constraint standard.

Predicting acute small-bowel toxicity in patients with rectal cancer treated with neoadjuvant chemoradiation: A comparison of peritoneal space versus small-bowel loop contouring techniques.

2012 ◽  
Vol 30 (4_suppl) ◽  
pp. 673-673
Author(s):  
Robyn Banerjee ◽  
Santam Chakraborty ◽  
Ian Nygren ◽  
Richie Sinha
Keyword(s):  
Rectal Cancer ◽  
Logistic Regression ◽  
Small Bowel ◽  
Cancer Patients ◽  
Locally Advanced ◽  
Neoadjuvant Chemoradiotherapy ◽  
Characteristic Analysis ◽  
Dose Volume ◽  
Peritoneal Space ◽  
Grade 3

673 Background: In lieu of contouring individual small bowel loops, the peritoneal space (PS) has been suggested as a possible surrogate volume for predicting small bowel toxicity. A dose-volume relationship for the PS has not been firmly established. The aim of this study was to determine whether contours of the PS better predict significant acute small bowel toxicity in neoadjuvant rectal cancer patients when compared with contours of individual small bowel loops. Methods: A standardized contouring method was developed for the PS and retrospectively applied to the radiation treatment plans of sixty-seven patients treated with neoadjuvant chemoradiotherapy for rectal cancer. All patients had locally advanced disease, no evidence of metastases, and received concurrent radiation and infusional 5-Fluorourocil chemotherapy. Dose-volume histogram (DVH) data was extracted and analyzed against patient toxicity. Receiver operating characteristic analysis and logistic regression was carried out for both contouring methods. Results: Grade ≥ 3 small bowel toxicity occurred in 16% (11/67) of patients. Volumes of the contoured small bowel loops correlated with grade ≥ 3 toxicity at each 5 Gray (Gy) dose level from 5 to 45 Gy, with the greatest area under the curve (AUC) measuring .964 (p=.000) associated with the volume receiving at least 25 Gy (V25). Volumes of the contoured PS predicted toxicity from 5 to 40 Gy, with the greatest AUC also at the V25 and measuring .896 (p=.000). Logistic regression analysis demonstrated a less than 15% risk of acute grade ≥ 3 toxicity was associated with a V25 of 215 cc for the small bowel and 710 cc for the PS. Conclusions: DVH analysis of peritoneal space volumes predicts grade ≥ 3 small bowel toxicity in neoadjuvant rectal cancer patients, suggesting the peritoneal space is a reasonable surrogate for contouring individual small bowel loops. However, contouring individual small bowel loops is a more sensitive method for predicting toxicity at each dose increment. For both contouring methods, the greatest sensitivity for predicting toxicity was associated with the volume receiving at least 25 Gy (V25).

scholarly journals Intensity-modulated Radiotherapy for Rectal Cancer in the UK in 2020

2021 ◽  
Author(s):  
C.R. Hanna ◽  
F. Slevin ◽  
A. Appelt ◽  
M. Beavon ◽  
R. Adams ◽  
...  
Keyword(s):  
Rectal Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Intensity Modulated ◽  
The Uk

scholarly journals Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume

2006 ◽  
Vol 13 (3) ◽  
pp. 108-115 ◽  
Author(s):  
O. Ballivy ◽  
W. Parker ◽  
T. Vuong ◽  
G. Shenouda ◽  
H. Patrocinio
Keyword(s):  
Spinal Cord ◽  
At Risk ◽  
Neck Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Ct Scans ◽  
Target Coverage ◽  
Geometric Uncertainties ◽  
Intensity Modulated ◽  
Organ At Risk

We assessed the effect of geometric uncertainties on target coverage and on dose to the organs at risk (OARS) during intensity-modulated radiotherapy (IMRT) for head-and-neck cancer, and we estimated the required margins for the planning target volume (PTV) and the planning organ-at-risk volume (PRV). For eight headand- neck cancer patients, we generated IMRT plans with localization uncertainty margins of 0 mm, 2.5 mm, and 5.0 mm. The beam intensities were then applied on repeat computed tomography (CT) scans obtained weekly during treatment, and dose distributions were recalculated. The dose–volume histogram analysis for the repeat CT scans showed that target coverage was adequate (V100 ≥ 95%) for only 12.5% of the gross tumour volumes, 54.3% of the upper-neck clinical target volumes (CTVS), and 27.4% of the lower-neck CTVS when no margins were added for PTV. The use of 2.5-mm and 5.0-mm margins significantly improved target coverage, but the mean dose to the contralateral parotid increased from 25.9 Gy to 29.2 Gy. Maximum dose to the spinal cord was above limit in 57.7%, 34.6%, and 15.4% of cases when 0-mm, 2.5-mm, and 5.0-mm margins (respectively) were used for PRV. Significant deviations from the prescribed dose can occur during IMRT treatment delivery for headand- neck cancer. The use of 2.5-mm to 5.0-mm margins for PTV and PRV greatly reduces the risk of underdosing targets and of overdosing the spinal cord.

Intensity modulated radiation therapy (IMRT) in the radiotherapy treatment of colo-rectal cancer: the influence of profile smoothing on the efficiency of delivery

2002 ◽  
Vol 2 (4) ◽  
pp. 189-198 ◽  
Author(s):  
W. Laub ◽  
D. Yan ◽  
J. Robertson ◽  
A. Martinez
Keyword(s):  
Rectal Cancer ◽  
Radiation Therapy ◽  
Small Bowel ◽  
Intensity Modulated Radiation Therapy ◽  
Smoothing Function ◽  
Treatment Technique ◽  
Intensity Modulated ◽  
Treatment Implementation ◽  
Close Proximity ◽  
Radiotherapy Treatment

Small bowel toxicity due to radiotherapy treatment of rectal cancer is common. The potential use of intensity modulated radiation therapy (IMRT) to reduce the volume of small bowel irradiated during radiation therapy (RT) for cancer has previously been reported. However, IMRT treatment implementation is relatively difficult for these patients. The PTV is large and has a concave shape, with the small bowel in very close proximity. Therefore, the intensity profile calculated by an inverse planning engine could be highly modulated and complicated to deliver.In this study, two methods were used to optimise IMRT plans for rectal cancer patients. Scatter contribution when backprojecting dose values to fluence values and a smoothing function were only implemented in the optimisation searching of one method. A common arrangement of five beams, each separated by equal gantry angle, was adopted. With both methods used, the dose coverage of the PTV was satisfactory. Small bowel irradiated to a dose of 95 % was reduced by about 70% as compared to a 3D conformal 3-field treatment technique. However, incorporation of scatter contribution and a smoothing function in the iteration of optimisation searching greatly reduced the degree of modulation in the two-dimensional intensity profiles. Instead of 120–160 step-and-shoot MLC segments only 30–60 segments were necessary to deliver the five intensity profiles. The number of monitor units per fraction was reduced accordingly to about one half. Therefore, by controlling the smoothness of the intensity profiles during optimisation, the produced IMRT plans could be delivered more efficiently. Moreover, the possibility to account for overlap of organs was found to be very valuable to avoid hot spots in these regions and to get the full DVHs of all organs at the same time.

Sign in / Sign up

Export Citation Format

Share Document