title: The dose distribution of low dose rate Cs-137 in intracavitary brachytherapy: comparison of Monte Carlo simulation, treatment planning calculation and polymer gel measurement.
abstract: In this study, the dose distribution delivered by low dose rate Cs-137 brachytherapy sources was investigated using Monte Carlo (MC) techniques and polymer gel dosimetry. The results obtained were compared with a commercial treatment planning system (TPS). The 20 mm and the 30 mm diameter Selectron vaginal applicator set (Nucletron) were used for this study. A homogeneous and a heterogeneous-with an air cavity-polymer gel phantom was used to measure the dose distribution from these sources. The same geometrical set-up was used for the MC calculations. Beyond the applicator tip, differences in dose as large as 20% were found between the MC and TPS. This is attributed to the presence of stainless steel in the applicator and source set, which are not considered by the TPS calculations. Beyond the air cavity, differences in dose of around 5% were noted, due to the TPS assuming a homogeneous water medium. The polymer gel results were in good agreement with the MC calculations for all the cases investigated.
authors.affiliation: Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Trust, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Fragoso
authors.forename: P A
authors.initials: PA
authors.lastname: Love
authors.forename: F
authors.initials: F
authors.lastname: Verhaegen
authors.forename: C
authors.initials: C
authors.lastname: Nalder
authors.forename: A M
authors.initials: AM
authors.lastname: Bidmead
authors.forename: M
authors.initials: M
authors.lastname: Leach
authors.forename: S
authors.initials: S
authors.lastname: Webb
mesh_terms: D001822:Body Burden; D001918:Brachytherapy / Q000379:methods*; D002588:Cesium Radioisotopes / Q000627:therapeutic use*; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005782:Gels / Q000528:radiation effects; D005833:Genital Neoplasms, Female / Q000532:radiotherapy*; D006801:Humans; D008954:Models, Biological; D009928:Organ Specificity; D019047:Phantoms, Imaging; D011108:Polymers / Q000528:radiation effects; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002588:Cesium Radioisotopes; D005782:Gels; D011108:Polymers; D019275:Radiopharmaceuticals