Measurement of rectum dose by in vivo alanine/ESR dosimetry in gynecological 192 Ir HDR brachytherapy Carlos Bravo-Miranda a, b , Amanda Burg Rech b , Harley Francisco Oliveira c , Edenyse Bertucci d , Teodoro Cordova-Fraga a , Oswaldo Baffa e, * a Departamento de Ingeniería Física DCI, Universidad de Guanajuato campus Le on, Guanajuato, Mexico b Departamento de Física, FFCLRP, Universidade de S~ ao Paulo, SP, Brazil c Faculdade de Medicina de Ribeir~ ao Preto and Hospital das Clínicas-FMRP, Universidade de S~ ao Paulo, SP, Brazil d Hospital das Clínicas-FMRP, Universidade de S~ ao Paulo, SP, Brazil e Universidade de S~ ao Paulo, Faculdade de Filosofia Ci^ encias e Letras de Ribeir~ ao Preto, Departamento de Física, Av. Bandeirantes, 3900, Monte Alegre, 14040901, Ribeir~ ao Preto, SP, Brazil highlights  ESR spectroscopy using alanine was used for HDR BT dosimetry.  The studies were conducted in phantom and in vivo.  The aim was to verify if the dose in rectum complies with ICRU Report 38 recommendations.  Only 1 of the 10 patients presented a rectum dose above the recommended level. article info Article history: Received 4 April 2014 Received in revised form 6 March 2015 Accepted 9 March 2015 Available online 11 March 2015 Keywords: Brachytherapy HDR In vivo dosimetry Alanine Electron Spin Resonance abstract High dose rate (HDR) brachytherapy (BT) used in treatments of gynecological cancer often results in high doses in the pelvic organs at risk (OARs) and the complications in the rectum are a serious concern. Dosimetry procedures in vivo can be used as an evaluation method of calculated dose in treatment planning. One dosimetric method is the use of alanine with electron spin resonance (ESR) that has been used in different clinical practices. The aim of this study was to indicate the dose level in the female rectum volume, using alanine dosimeters during 192 Ir HDR gynecological BT, for cervical cancer. Doses were compared with the values obtained using the computational treatment planning system based on two orthogonal radiographic images. Firstly a phantom study in water was performed, enabling the in vivo study. Ten patients had the dose in rectum measured, resulting from 10 points properly referred; variations found were in the range of þ60% and 50% of the delivered doses compared to the treatment planning system. Differences between planned and measured doses can be mainly due to uncertainty of dosimeter position determination, averaging of dose points specified over the whole dosimeter position, uncontrolled changes in detector position during treatment due to rectum movement and to a simplified treatment system planning, that do not take into account the details of the patient anatomy and the difference among the tissues. Results show that improvements of the protocol treatment should be done to enhance the relation between treatment planning system and experimental results, nevertheless the dose at the OARs was lower than the recommended by the ICRU Report 38. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction The efficacy of radiotherapy, either external beam therapy or brachytherapy (BT), depends highly upon the precision of the prescribed dose delivery to the target volume. When there is a difference between planned and delivered doses, either the * Corresponding author. E-mail addresses: mirbrac_17@hotmail.com (C. Bravo-Miranda), aburgrech@ gmail.com (A.B. Rech), harley@fmrp.usp.br (H.F. Oliveira), edenysebertucci@ hotmail.com (E. Bertucci), theocordova@yahoo.com (T. Cordova-Fraga), baffa@usp. br (O. Baffa). Contents lists available at ScienceDirect Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas http://dx.doi.org/10.1016/j.radmeas.2015.03.006 1350-4487/© 2015 Elsevier Ltd. All rights reserved. Radiation Measurements 75 (2015) 45e52