title: Concentration modulated skin marker for radiotherapy treatment planning process.
abstract: OBJECTIVE
  For conformal radiotherapy, it is feasible to achieve high accuracy in contouring the outline of the target volume in treatment planning process. In contouring process, target volume is occasionally defined by means of either surgical clips or skin marker during patient anatomical data acquisition. Treatment planning systems are predicting invalid radiation dose distributions by using surgical clips and skin marker within the patient. Purpose of this study is the production of new skin marker which affects less dose distributions of electron beam.
  
  
  METHODS
  The influences of lead and commercial markers on dose calculations in a 3D treatment planning systems were investigated in terms of electron beam energy and dose profile depth. Dose deviation with commercial marker was observed to smaller than lead marker. However this dose deviation was still at big value. In order to reduce of this value, barium sulfate suspension and ultrasound gel were mixed with different volumetric ratio. With the purpose of acception the most suitable marker for radiation therapy, obtained new suspensions were investigated in terms of visibility and dose deviation.
  
  
  RESULTS
  B:G/1:10 marker was determined to cause optimum visibility and the lowest dose deviation on dose calculations in terms of electron beam energy and dose profile depth.
  
  
  CONCLUSIONS
  Appropriate marker, mixture of substances such as barium sulfate suspension and ultrasound gel can be produced. This marker is both ease of usage and practical and economical. Each clinic can prepare marker which is peculiar to suspension with different concentration of substance for specific visibility. But, it should be taken into account resultant dose deviation to beam calculation depending on barium sulfate concentration.
authors.affiliation: Department of Radiation Oncology, Cumhuriyet University, Faculty of Medicine, TR-58140 Sivas, Turkey. yildq@hotmail.com
authors.forename: Yıldıray
authors.initials: Y
authors.lastname: Özgüven
authors.forename: Birsen
authors.initials: B
authors.lastname: Yücel
authors.forename: Betül
authors.initials: B
authors.lastname: Özyürek
authors.forename: Gülderen
authors.initials: G
authors.lastname: Karakuş
authors.forename: Yücel
authors.initials: Y
authors.lastname: Özgüven
mesh_terms: D004583:Electrons / Q000627:therapeutic use; D057918:Fiducial Markers; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards*; D012867:Skin / Q000000981:diagnostic imaging / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed