title: (90)Y-PET/CT Imaging Quantification for Dosimetry in Peptide Receptor Radionuclide Therapy: Analysis and Corrections of the Impairing Factors.
abstract: OBJECTIVE
  We evaluated the possibility to assess (90)Y-PET/CT imaging quantification for dosimetry in (90)Y-peptide receptor radionuclide therapy.
  
  
  METHODS
  Tests were performed by Discovery 710 Elite (GE) PET/CT equipment. A body-phantom containing radioactive-coplanar-spheres was filled with (90)Y water solution to reproduce different signal-to-background-activity-ratios (S/N). We studied minimum detectable activity (MDA) concentration, contrast-to-noise ratio (CNR), and full-width-at-half-maximum (FWHM). Subsequently, three recovery coefficients (RC)-based correction approaches were evaluated: maximum-RC, resolution-RC, and isovolume-RC. The analysis of the volume segmentation thresholding method was also assessed to derive a relationship between the true volume of the targets and the threshold to be applied to the PET images. (90)Y-PET/CT imaging quantification was then achieved on some patients and related with preclinical tests. Moreover, the dosimetric evaluation was obtained on the target regions.
  
  
  RESULTS
  CNR value was greater than 5 if the MDA was greater than 0.2 MBq/mL with no background activity and 0.5-0.7 MBq/mL with S/N ranging from 3 to 6. FWHM was equal to 7 mm. An exponential fitting of isovolume RCs-based correction technique was adopted for activity quantification. Adaptive segmentation thresholding exponential curves were obtained and applied for target volume identification in three signal-to-background-activity-ratios. The imaging quantification study and dosimetric evaluations in clinical cases was feasible and the results were coherent with those obtained in preclinical tests.
  
  
  CONCLUSIONS
  (90)Y-PET/CT imaging quantification is possible both in phantoms and in patients. Absorbed dose evaluations in clinical applications are strongly related to targets activity concentration.
authors: 1 Physics and Biomedical Technologies Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .|2 Medical Physics Unit, AORMN , Pesaro, Italy .
authors: Cinzia
authors: C
authors: Fabbri
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Mirco
authors: M
authors: Bartolomei
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Vincenzo
authors: V
authors: Mattone
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Michela
authors: M
authors: Casi
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Francesco
authors: F
authors: De Lauro
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Nerio
authors: N
authors: Bartolini
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Giovanni
authors: G
authors: Gentili
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Sonia
authors: S
authors: Amadori
authors: 3 Nuclear Medicine Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Monica
authors: M
authors: Agostini
authors: 1 Physics and Biomedical Technologies Unit, Bufalini Hospital , AUSL della Romagna, Cesena, Italy .
authors: Graziella
authors: G
authors: Sarti
mesh_terms: D000368:Aged; D006801:Humans; D007668:Kidney / Q000528:radiation effects*; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D018358:Neuroendocrine Tumors / Q000532:radiotherapy*; D010190:Pancreatic Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics* / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D017481:Receptors, Somatostatin; D059629:Signal-To-Noise Ratio; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D015021:Yttrium Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; D015021:Yttrium Radioisotopes
keywords: 90Y-PET/CT imaging; contrast-to-noise ratio; dosimetry; image texture analysis; minimum detectable activity; recovery coefficients; segmentation thresholding method