title: A study of image-guided intensity-modulated radiotherapy with fiducials for localized prostate cancer including pelvic lymph nodes.
abstract: OBJECTIVE
  To study the impact on nodal coverage and dose to fixed organs at risk when using daily fiducial localization of the prostate to deliver intensity-modulated radiotherapy (IMRT).
  
  
  METHODS
  Five patients with prostate cancer in whom prostate and pelvic nodes were irradiated with IMRT were studied. Dose was prescribed such that 95% of the prostate planning target volume (PTV) and 90% of the nodal PTV were covered. Random and systematic prostate displacements in the anterior-posterior, superior-inferior, and left-right directions were simulated to shift the original isocenter of the IMRT plan. The composite dose during the course of treatment was calculated.
  
  
  RESULTS
  Compared with a static setup, simulating random shifts reduced dose by less than 1.5% for nodal hotspot (i.e., dose to 1 cm(3)), by less than 1% for the 90% nodal PTV coverage, and by less than 0.5% for the nodal mean dose. Bowel and femoral head hotspots were reduced by less than 1.5% and 2%, respectively. A 10-mm systematic offset reduced nodal coverage by up to 10%.
  
  
  CONCLUSIONS
  The use of prostate fiducials for daily localization during IMRT treatment results in negligible changes in dose coverage of pelvic nodes or normal tissue sparing in the absence of a significant systematic offset. This offers a simple and practical solution to the problem of image-guided radiotherapy for prostate cancer when including pelvic nodes.
authors: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305-5847, USA.
authors: Annie
authors: A
authors: Hsu
authors: Todd
authors: T
authors: Pawlicki
authors: Gary
authors: G
authors: Luxton
authors: Wendy
authors: W
authors: Hara
authors: Christopher R
authors: CR
authors: King
mesh_terms: D006801:Humans; D008198:Lymph Nodes / Q000528:radiation effects; D008207:Lymphatic Metastasis; D008297:Male; D009928:Organ Specificity; D010386:Pelvic Neoplasms / Q000532:radiotherapy*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*