title: Assaying multiple (125)I seeds with the well-ionization chamber SourceCheck(4π) 33005 and a new insert.
abstract: OBJECTIVE
  To provide a practical solution that can be adopted in clinical routine to fulfill the AAPM-ESTRO recommendations regarding quality assurance of seeds used in prostate permanent brachytherapy. The aim is to design a new insert for the well-ionization chamber SourceCheck(4π) 33005 (PTW, Germany) that allows evaluating the mean air-kerma strength of up to ten (125)I seeds with one single measurement instead of measuring each seed individually.
  
  
  METHODS
  The material required is: a) the SourceCheck(4π) 33005 well-ionization chamber provided with a PTW insert to measure the air-kerma strength S K of one single seed at a time; b) a newly designed insert that accommodates ten seeds in one column, which allows measuring the mean S K of the ten seeds in one single measurement; and c) a container with ten seeds from the same batch and class of the seeds used for the patient implant, and a set of nine non-radioactive seeds. The new insert is characterized by determining its calibration coefficient, used to convert the reading of the well-chamber when ten seeds are measured to their mean S K . The proposed method is validated by comparing the mean S K of the ten seeds obtained from the new insert with the individual measurement of S K of each seed, evaluated with the PTW insert.
  
  
  RESULTS
  The ratio between the calibration coefficient of the new insert and the calibration coefficient of the PTW insert for the SourceCheck(4π) 33005 is 1.135 ± 0.007 (k = 1). The mean S K of a set of ten seeds evaluated with this new system is in agreement with the mean value obtained from measuring independently the S K of each seed.
  
  
  CONCLUSIONS
  The new insert and procedure allow evaluating the mean S K of ten seeds prior to the implant in a single measurement. The method is faster and more efficient from radiation protection point of view than measuring the individual S K of each seed.
authors.affiliation: Physics Section, Department of Radiation Oncology, La Fe University and Polytechnic Hospital, Valencia; National Dosimetry Centre (CND), Valencia.
authors.forename: Cristian
authors.initials: C
authors.lastname: Candela-Juan
authors.affiliation: Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot, Valencia.
authors.forename: Facundo
authors.initials: F
authors.lastname: Ballester
authors.affiliation: Physics Section, Department of Radiation Oncology, La Fe University and Polytechnic Hospital, Valencia; Department of Radiotherapy, Clínica Benidorm, Benidorm.
authors.forename: Jose
authors.initials: J
authors.lastname: Perez-Calatayud
authors.affiliation: Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot, Valencia; IFIC (CSIC-UV), Burjassot, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Vijande
keywords: brachytherapy; insert; prostate; quality assurance; seeds; well chamber
references.citation: Med Phys. 2005 Nov;32(11):3375-8
references.pmid: 16370425
references.citation: J Appl Clin Med Phys. 2005 Winter;6(1):22-50
references.pmid: 15770195
references.citation: Med Phys. 2007 Jun;34(6):1975-82
references.pmid: 17654900
references.citation: J Contemp Brachytherapy. 2012 Mar;4(1):21-8
references.pmid: 23346136
references.citation: Med Phys. 2008 Sep;35(9):3860-5
references.pmid: 18841836
references.citation: Int J Radiat Oncol Biol Phys. 1998 Apr 1;41(1):217-22
references.pmid: 9588936