Accuracy of dose planning for prostate radiotherapy in the presence of metallic implants evaluated by electron spin resonance dosimetry

Abstract

Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.

A phantom to study the effects of metallic prostheses in radiotherapy by gel dosimetry

“…Currently available dosimeters, such as Ionization Cameras (IC), diodes arrays, thermoluminescent dosimeters (TLDs) and Radiographic Films provide dose distributions at one point or in two dimensions [5]. In a recent work, Electron Spin Resonance dosimetry with alanine, which has a flat response above energy of 100kV, was also used to measure dose in the prostate region [8]. For dose measurements in 3D, however, the use of several dosimeters is required, resulting in a procedure that is much more complicated, yet does not provide high spatial resolution, except in the case of Films.…”

Dosimetria 3D de um tratamento simulado de próstata na presença de próteses femorais metálicas.

“…Dosímetros atualmente disponíveis, tais como câmeras de Ionização (IC), arranjos de diodos, dosímetros termoluminescentes (TLDs) e filmes radiográficos fornecem distribuições de doses em um ponto ou em duas dimensões [17]. Em um trabalho recente, Dosimetria de Ressonância de Spin-Eletrônico (ESR) com alanina, que tem uma resposta plana em energia acima de 100kV, foi usada para medir a dose na região da próstata [20]. Para medições de dose em 3D, não obstante,é requerido o uso de muitos dosímetros, resultando em um procedimento muito mais complicado, que ainda não fornece uma alta resolução espacial, exceto no caso dos filmes.…”

Campos pequenos de radiação e materiais alternativos em dosimetria com espectroscopia de ressonância magnética eletrônica

“…One of the advantages is that it presents effective atomic number (zeff) close to water (Vestad et al, 2004a), and a single line spectrum, which is less complex than alanine signal, as the models in figure 18. Thus, as alanine was investigated in clinical applications (Chu et al, 1989;Gall et al, 1996;Kuntz et al, 1996;De Angelis et al, 1999;De Angelis et al, 2000;Cieszielski et al, 2003;Schultka et al, 2006;Wagner et al, 2008;Schaeken et al, 2010;Garcia et al, 2011;Wagner, Anton and Vorwerk, 2011;Tanderup et al, 2013;Rech et al, 2014;Alves et al, 2015;BravoMiranda et al, 2015) so was lithium formate (Gustafsson, Lund and Olsson, 2008;Adolfsson et al, 2010;Waldeland et al, 2010a). In general, literature presents investigation with several organic compounds for EMR dosimetry (Hassan, Ikeya and Toyoda, 1998;Olsson et al, 1999;Hassan, Ulusoy and Ikeya, 2000;Gustafsson et al, 2004;Sharaf and Hassan, 2004;Yurus, Ozbey and Korkmaz, 2004;Danilczuk et al, 2008;Davidson and Jordan, 2009;Popoca and Ureña-Núñez, 2009;Ureña-Núñez and Ballesteros, 2009;Gustafsson, Lund and Lund, 2011;Lelie et al, 2013;Negron-Mendoza et al, 2015;Rushdi et al, 2015;Nor et al, 2016), especially for high dose.…”