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This model has been utilized for the development of a comprehensive source quality assurance (QA) method using radiochromic film (RCF) dosimetry including assessment of different digitization uncertainties.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>An algorithm was developed and verified to generate 2D dose maps of the mHDR\u2010V2 <jats:sup>192<\/jats:sup>Ir source (Elekta, Veenendaal, Netherlands) based on the AAPM TG\u201043 formalism. The limits of the dosimetric error associated with source (0.9\u00a0mm diameter) positional uncertainty were evaluated and experimentally verified with EBT3 film measurements for 6F (2.0\u00a0mm diameter) and 4F (1.3\u00a0mm diameter) size catheters at the surface (4F, 6F) and 10\u00a0mm further (4F only). To quantify this uncertainty, a source tracking model was developed to incorporate the unique geometric features of all isodose lines (IDLs) within any given 2D dose map away from the source. The tracking model normalized the dose map to its maximum, then quantified the IDLs using blob analysis based on features such as area, perimeter, weighted centroid, elliptic orientation, and circularity. The Pearson correlation coefficients (PCCs) between these features and source coordinates (<jats:italic>x<\/jats:italic>, <jats:italic>y<\/jats:italic>, <jats:italic>z<\/jats:italic>, <jats:italic>\u03b8<jats:sub>y<\/jats:sub><\/jats:italic>, <jats:italic>\u03b8<jats:sub>z<\/jats:sub><\/jats:italic>) were calculated. To experimentally verify the accuracy of the tracking model, EBT3 film pieces were positioned within a Solid Water\u00ae (SW) phantom above and below the source and they were exposed simultaneously.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The maximum measured dosimetric variations on the 6F and 4F catheter surfaces were 39.8% and 36.1%, respectively. At 10\u00a0mm further, the variation reduced to 2.6% for the 4F catheter which is in agreement with the calculations. The source center (<jats:italic>x<\/jats:italic>, <jats:italic>y<\/jats:italic>) was strongly correlated with the low IDL\u2010weighted centroid (PCC\u00a0=\u00a00.99), while the distance to source (<jats:italic>z<\/jats:italic>) was correlated with the IDL areas (PCC\u00a0=\u00a00.96) and perimeters (PCC\u00a0=\u00a00.99). The source orientation <jats:italic>\u03b8<jats:sub>y<\/jats:sub><\/jats:italic> was correlated with the difference between high and low IDL\u2010weighted centroids (PCC\u00a0=\u00a00.98), while <jats:italic>\u03b8<jats:sub>z<\/jats:sub><\/jats:italic> was correlated with the elliptic orientation of the 60\u201390% IDLs (PCC\u00a0=\u00a00.97) for a maximum distance of <jats:italic>z<\/jats:italic>\u00a0=\u00a05\u00a0mm. Beyond 5\u00a0mm, IDL circularity was significant, therefore limiting the determination of <jats:italic>\u03b8<jats:sub>z<\/jats:sub><\/jats:italic> (PCC\u00a0\u2264\u00a00.48). The measured positional errors from the film sets above and below the source indicated a source position at the bottom of the catheter (\u22120.24\u00a0\u00b1\u00a00.07\u00a0mm).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Isodose line features of a 2D dose map away from the HDR source can reveal its spatial coordinates. RCF was shown to be a suitable dosimeter for source tracking and dosimetry. This technique offers a novel source QA method and has the potential to be used for QA of commercial and customized applicators.<\/jats:p><\/jats:sec>","DOI":"10.1002\/mp.14540","type":"journal-article","created":{"date-parts":[[2020,10,16]],"date-time":"2020-10-16T18:37:21Z","timestamp":1602873441000},"page":"6122-6139","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Positional and angular tracking of HDR <sup>192<\/sup>Ir source for brachytherapy quality assurance using radiochromic film dosimetry"],"prefix":"10.1002","volume":"47","author":[{"given":"Saad","family":"Aldelaijan","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology Dana Farber\/Brigham and Women\u2019s Cancer Center Harvard Medical School Boston MA 02115 USA"},{"name":"Department of Biomedical Engineering Montreal Neurological Institute McGill University Montr\u00e9al QC H3A 2B4 Canada"},{"name":"Medical Physics Unit McGill University Montr\u00e9al QC H4A 3J1 Canada"},{"name":"Department of Radiation Oncology SMBD Jewish General Hospital Montr\u00e9al QC H3T 1E2 Canada"},{"name":"Biomedical Physics Department King Faisal Specialist Hospital &amp; Research Centre Riyadh 12713 Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Slobodan","family":"Devic","sequence":"additional","affiliation":[{"name":"Medical Physics Unit McGill University Montr\u00e9al QC H4A 3J1 Canada"},{"name":"Department of Radiation Oncology SMBD Jewish General Hospital Montr\u00e9al QC H3T 1E2 Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hamed","family":"Bekerat","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology SMBD Jewish General Hospital Montr\u00e9al QC H3T 1E2 Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pavlos","family":"Papaconstadopoulos","sequence":"additional","affiliation":[{"name":"Netherlands Cancer Institute Amsterdam 1066 CX Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James","family":"Schneider","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology SMBD Jewish General Hospital Montr\u00e9al QC H3T 1E2 Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jan","family":"Seuntjens","sequence":"additional","affiliation":[{"name":"Medical Physics Unit McGill University Montr\u00e9al QC H4A 3J1 Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert A.","family":"Cormack","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Dana Farber\/Brigham and Women\u2019s Cancer Center Harvard Medical School Boston MA 02115 USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ivan M.","family":"Buzurovic","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology Dana Farber\/Brigham and Women\u2019s Cancer Center Harvard Medical School 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