<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2021000600009</article-id>
<article-id pub-id-type="doi">10.31349/revmexfis.67.061101</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Evaluation of the impact of parameters on the gamma index for breast cancer treatments]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Querebalú Garcia]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Carrasco Solis]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Valladolid Salazar]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Centeno Ramos]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Instituto Nacional de Enfermedades Neoplásicas  ]]></institution>
<addr-line><![CDATA[Lima ]]></addr-line>
<country>Perú</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional de Ingeniería  ]]></institution>
<addr-line><![CDATA[Lima ]]></addr-line>
<country>Peru</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad Nacional Mayor de San Marcos  ]]></institution>
<addr-line><![CDATA[Lima ]]></addr-line>
<country>Peru</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>12</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>12</month>
<year>2021</year>
</pub-date>
<volume>67</volume>
<numero>6</numero>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2021000600009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2021000600009&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2021000600009&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Volumetric modulated arc radiotherapy treatments (VMAT) can achieve highly conformed dose distributions however, due to the complexity of the technique, there may have differences between the planned and administered dose distributions, generated by the precision in the dose calculation of the treatment planning system (TPS) or by the errors associated with it. One way to quantify the difference between both dose distributions is by using the gamma index; however, there is no accord regarding the parameters that should be used in its analysis. On the other hand, this gamma index may depend on the pathology and the area to be treated. For this reason, the present work aims to evaluate different parameters of the analysis of the gamma index for breast cancer treatments; these are local and global normalization, the analysis criteria (1%/1 mm, 2%/2 mm, 3%/2 mm, 2%/3 mm, 3%/3 mm and 5%/3 mm), and the low dose threshold (LDT) of 5% and 10%. For this, 30 treatment plans performed with VMAT technique in a 6 MV Infinity linear accelerator (Elekta, Stockholm, Sweden) were analyzed, calculated with the TPS Monaco V.5.11.03 (Elekta, Stockholm, Sweden) and measured with the Octavius 4D system (PTW, Freiburg, Germany). The results of the analysis of the global gamma index were of a gamma passing rate (%GP) greater than 95% for analysis criteria of 3%/3 mm and 5%/3 mm; however, for these same parameters in the local gamma index analysis, the results are 85.8% and 91.1% respectively. In addition, from the LDT evaluation, it is observed that there is a mean increase of %GP for the local gamma index analysis and a mean decrease of %GP for the global gamma index analysis, for the LDT from 5% to 10%. On the other hand, the standard deviation is lower in the global gamma index; analysis than in the local one, and it decreases when the analysis criteria are less strict. It is concluded that there is not a great difference in choosing the LDT of 5% or 10%. When the gamma analysis criteria are less strict, the %GP increases both for the analysis of the local and global gamma index, taking this into account, each parameter should be used carefully according to the treatment plan to be analyzed, taking into account the advantages and disadvantages of each parameter.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Gamma index]]></kwd>
<kwd lng="en"><![CDATA[VMAT]]></kwd>
<kwd lng="en"><![CDATA[lower dose threshold]]></kwd>
<kwd lng="en"><![CDATA[analysis criteria]]></kwd>
<kwd lng="en"><![CDATA[patient specific quality control]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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