Reporting small bowel dose in cervix cancer high-dose- rate brachytherapy Yixiang Liao, Ph.D., Virag Dandekar, M.D., James C.H. Chu, Ph.D., Julius Turian, Ph.D., Damian Bernard, Ph.D., and Krystyna Kiel, M.D. Department of Radiation Oncology, Rush University Medical Center, Chicago, IL ARTICLE INFO Article history: Received 16 December 2014 Received in revised form 12 March 2015 Accepted 10 June 2015 Keywords: HDR Small bowel Cervical cancer Late toxicity ABSTRACT Small bowel (SB) is an organ at risk (OAR) that may potentially develop toxicity after radiotherapy for cervix cancer. However, its dose from brachytherapy (BT) is not systematically reported as in other OARs, even with image-guided brachytherapy (IGBT). This study aims to introduce consideration of quantified objectives for SB in BT plan optimization and to evaluate the feasibility of sparing SB while maintaining adequate target coverage. In all, 13 patients were included in this retrospective study. All patients were treated with external beam radiotherapy (EBRT) 45 Gy in 25 fractions followed by high dose rate (HDR)- BT boost of 28 Gy in 4 fractions using tandem/ring applicator. Magnetic resonance imaging (MRI) and computed tomographic (CT) images were obtained to define the gross tumor volume (GTV), high-risk clinical target volume (HR-CTV) and OARs (rectum, bladder, sigmoid colon, and SB). Treatment plans were generated for each patient using GEC-ESTRO recommendations based on the first CT/MRI. Treatment plans were revised to reduce SB dose when the D 2 cm 3 dose to SB was 4 5 Gy, while maintaining other OAR constraints. For the 7 patients with 2 sets of CT and MRI studies, the interfraction variation of the most exposed SB was analyzed. Plan revisions were done in 6 of 13 cases owing to high D 2 cm 3 of SB. An average reduction of 19% in D 2 cm 3 was achieved. Meeting SB and other OAR constraints resulted in less than optimal target coverage in 2 patients (D 90 of HR-CTV o 77 Gy αβ10 ). The highest interfraction variation was observed for SB at 16  59%, as opposed to 28  27% for rectum and 21  16% for bladder. Prospective reporting of SB dose could provide data required to establish a potential correlation with radiation-induced late complication for SB. & 2015 American Association of Medical Dosimetrists. Introduction Brachytherapy (BT) has been used in the curative management of cervical carcinoma for more than a century. Assessment of efficacy and toxicity was based on point-based dosimetry and 2- dimensional planning. 1 Image (computed tomographic [CT]/mag- netic resonance imaging [MRI])-guided brachytherapy (IGBT), which allows true evaluation of dose for assessment of control and toxicity, was introduced in the late 1990s but did not gain widespread acceptance in the community until the late 2000s. Recently, the Gynaecological (GYN) GEC-ESTRO working group has issued a series of recommendations on multiple aspects of MRI- based BT for cervical cancer, 2-5 including dose-volume parameters to be reported for organs at risk (OARs) (rectum, bladder, and sigmoid colon). 5 Other institutions have recommended dose- volume constraints for these OARs based on their own clinical experiences. 6,7 Dose to small bowel (SB) from BT has not been reported widely, nor is there a guideline for dose reporting or recom- mendation for its dose constraint. Data from external beam radiotherapy (EBRT) clearly demonstrate that SB is more radio- sensitive than rectum, bladder, and large bowel. 6,8,9 A recent study has reported that SB exhibits the highest rate of radiation- induced late toxicity resulting from low-dose-rate (LDR) BT for cervical cancer. 10 With the capability of viewing patient's anatomy during IGBT, this study aims to introduce quantified objectives for SB in BT plan optimization and to evaluate the feasibility of sparing SB while maintaining target coverage. Our clinical outcomes were analyzed and a reporting scheme is proposed. journal homepage: www.meddos.org Medical Dosimetry http://dx.doi.org/10.1016/j.meddos.2015.06.005 0958-3947/Copyright Ó 2015 American Association of Medical Dosimetrists Reprint requests to Yixiang Liao, Ph.D., Department of Radiation Oncology, Rush University Medical Center, 500 South Paulina Street, Chicago, IL 60612. E-mail: yixiang_liao@rush.edu Medical Dosimetry ] (2015) ]]]–]]]