Measurement of rectum dose by in vivo alanine/ESR dosimetry in gynecological Ir-192 HDR brachytherapy

Autor(es)

Bravo-Miranda, Carlos ^{[1, 2]} ; Rech, Amanda Burg ^[1] ; Oliveira, Harley Francisco ^{[3, 4]} ; Bertucci, Edenyse ^[4] ; Cordova-Fraga, Teodoro ^[2] ; Baffa, Oswaldo ^[5]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Fis, FFCLRP, BR-05508 Sao Paulo, SP - Brazil

^[2] Univ Guanajuato, Dept Ingn Fis DCI, Guanajuato - Mexico

^[3] Univ Sao Paulo, Fac Med Ribeirao Preto, BR-05508 Sao Paulo, SP - Brazil

^[4] Univ Sao Paulo, Hosp Clin FMRP, BR-05508 Sao Paulo, SP - Brazil

^[5] Univ Sao Paulo, Dept Fis, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Radiation Measurements; v. 75, p. 45-52, APR 2015.
• Citações Web of Science: 2

Resumo

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 Ir-192 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 +60% 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. (C) 2015 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 13/03258-9 - Estudo e caracterização de materiais orgânicos para dosimetria de campos pequenos com ressonância magnética eletrônica
• Beneficiário: Amanda Burg Rech
• Modalidade de apoio: Bolsas no Brasil - Doutorado