Dosimetric comparison of organs at risk in 5 different radiotherapy plans in patients with preoperatively irradiated rectal cancer

Abstract

Background: Intensity-modulated radiotherapy (IMRT) is a widely used irradiation technique in rectal cancer patients. We aimed to compare 4 different IMRT plans with 3-dimensional conformal radiotherapy (3D-CRT) considering organs at risk (OARs) in patients with rectal carcinoma. Methods: This retrospective study included 27 rectal cancer patients who were irradiated preoperatively between January 2016 and December 2018. Five different plans (4-field 3D-CRT in 2 phases, 7-field IMRT in 2 phases, 9-field IMRT in 2 phases, 7-field simultaneous integrated boost [SIB] IMRT, and 9-field SIB IMRT) were generated for each patient. Comparison of 5 different plans according to bladder and bilateral femoral head mean doses, bladder V40, bilateral femoral head V40, and small bowel V35 values were evaluated. Results: Most of the OAR parameters significantly favored IMRT plans compared to the 3D-CRT plan. The largest difference was observed in bladder V40 values (reduction of V40 value up to 51.2% reduction) in favor of IMRT. In addition, SIB plans showed significantly better reduction in OARs than phase plans except for small bowel V35 values. Conclusions: IMRT plans reduced almost all the OARs doses compared with the 3D-CRT plan in rectal cancer patients. Furthermore, SIB plans demonstrated lower OAR doses than the phase plans. IMRT techniques, especially SIB plans, reduce OAR doses and provide safer doses for the treatment of rectal carcinoma.

New dosimetric parameters to predict ano-rectal toxicity during radiotherapy treatment

“…Consistently to previously reported experiences [23], the type of technique was significantly correlated to the development of toxicity events (p-value of 0.03). Also for the D 98% of the wall of the low anorectum, a statistical significance correlation was found (p-value of 0.043).…”

“…Buettner et al showed that the fraction of the circumference of the rectal wall irradiated at high doses is specifically important. Krol et al confirmed that less exposure of the rectal wall to intermediate or high doses of radiations, leads to fewer changes and complications [16,[23][24][25][26][27][28][29].…”

Rectum and Bladder Toxicity in Postoperative Prostate Bed Irradiation: Dose–Volume Parameters Analysis

“…We found that the rectal wall can be an important DVH structure. Lower doses to the rectal wall were associated with lower numbers of acute and late AEs, similar to previous studies [31][32][33][34]. Many studies reported an increased risk of late rectal bleeding when the rectum received higher RT doses [35][36][37].…”

Which radiotherapy technique is better for neoadjuvant treatment of rectal cancer: A dosimetric comparison

“…In our dosimetric study we compared the standard and traditionally used 3D-CRT technique with VMAT and HT for patients with locally advanced rectal cancer treated neoadjuvantly. In the literature, there are studies comparing different IMRT techniques with 3D-CRT, as well as with each other but no study has been published comparing 3D-CRT, VMAT, and HT techniques at the same time [14][15][16][17][18][19]. Traditionally, 3D-CRT has been used for LARC targeting the primary tumor and mesorectum as well as lymph nodes.…”