Home Enquiry Form Quotation Request Forms Brochure Request Form What's New Product Lists Product User Manuals Product Technical Notes Ultrasound Equipment Ultrasound Transducers Pre-Plugged Seed Needles Seeding/Biopsy Steppers Disposable Grids Disposable Drapes Endocavity Balloons Grid Adapters PAL Pro Stirrups OR Tables / Trolleys Source Measurement Electrometers Equipment Services Suggestions FAQ Search Useful Web Sites Training Courses Calibrations and Upgrades Intravascular Brachy LDR Calibrations Prostate Brachytherapy Prostate Biopsy 3D Prostate Mapping Prostate Cancer Prostate Seed Implant Mammography/Diagnostics Site Map External Beam/IMRT/CT Exradin Ion Chambers Prostate Scanning SeeDs and Strands Seed Implant Dosimetry HDR/PDR Dose Planning HDR MultiSource HDR Gynae Applicators HDR Gynae Template LDR/MDR Curietron HDR IU Sleeves HDR/IORT HAM Applicators HDR/IORT Breast Applicator HDR Prostate Brachy HDR Prostate Template AUTIMO Beam Systems Alloys and Alloy Melters Slideshow Bibliography Our Company Curietron Appeal Iridium-192 Wire Sources Eye Applicators Gold Fiduciary Markers Urology Biopsy Biopsy Guns/Needles Needles/Guns/Applications Clinical Oncology Needles Haematology Biopsy Interventional Radiology Urology Needles/Guns Breast Biopsy/Localisation Gynae Biopsy / Aspiration Skin Biopsy Punch Anaesthesia Needles Antenatal Diagnostic Needle Guides Syringe Holders Biopsy Grids Biopsy Steppers Infection Control-MultiMAT Bone Marrow Biopsy Vertebroplasty Laparoscopy Needles Laparoscopy Support Temno Adjustable Coaxial MRI Biopsy/Localisation Percutaneous Injection-PIA Portable Bladder Scanner Cryotherapy Brachytherapy Template Guided Biopsy Volume Studies Fiducial Marker Placement Micro-Touch Micro-Touch LP NEW EX3 Stepper Classic Stepper Multi-Purpose Workstation Stabilizers Steppers Brachy/Biopsy Accessories

 I/Pd Seed Measurement
Source Holders
HDR1000+ Well Chamber
IVB1000 Well Chamber
Ir-192 Wire Measurement
Ir Wire Loop Measurement
Ir Seeds in Ribbon Measurement
HDR Ir-192 Source Measurement
Metastron Measurement
RAPIDStrand Measurement
I/Pd Seed Measurement
Bard Cartridge
Seed QA
Measurement Justification
Chamber Recal & Upgrade
Calibration Systems
SIRAS System
Seed SourceCheck









Iodine and Palladium Seed Measurement

For Prostate Cancer Treatment

  • Calibration of Individual Seeds
  • Relative Calibration of Individual Palladium Seeds
  • Batch assay of up to 500 Iodine or Palladium Seeds

Individual Seed Measurements

Single seed measurements are performed with the Source Holder for Single LDR Seeds, SeeDOS Code 70016. This insert has a 1.2mm inner diameter Teflon® tube which positions the seed at the most sensitive area of the HDR 1000 Plus Ion Well Chamber. The smooth Teflon tube allows easy removal of the seed. Ion chamber calibrations from the University of Wisconsin ADCL are available for many iodine and palladium seeds.

Batch Assay Measurements

LDR brachytherapy treatment for prostate cancer uses high numbers of seeds. A treatment centre must sometimes receive up to 500 seeds if several cases are imminent. Individual seed calibration is too cumbersome. For these large numbers of seeds, a random sampling of at least 10% of the seeds should be calibrated2.

Measuring a quantity of seeds at the same time is performed with the Source Holder for LDR Seed Batch Assay, PN 70022(not shown). This source holder holds up to 500 of the iodine or palladium seeds typically used for prostate cancer treatment.

A batch of 6711 iodine seeds of activity 0.35 mR gives the following nominal signals.

Number of Seeds Amp Signal Coulomb Signal Coulomb Signal
50 0.085 nA 5.10 nC/60 sec 10.20 nC/120 sec
100 0.130 nA 7.80 nC/60 sec 15.6 nC/120 sec

Self absorption resulting from a large number of seeds being placed in the insert is significant. Because of this self absorption, correction factors must be experimentally obtained for each type of LDR seed used. This method is described very well in "Verification of manufacturer-supplied 125I and 103Pd air-kerma strengths." Mellenberg and Kline; Medical Physics. 22(9):1495-1497, 1995. Note, a correction factor for each isotope as shown in Fig. 2 should be determined for each individual well chamber upon receipt of the chamber.

Before each assay procedure, a constancy check should be performed to assure the integrity of the calibration system1. This should be done with a long half-life isotope such as caesium.

Verification of Calibration

For low dose rate brachytherapy, the standard of practice has shifted so that the manufacturer's calibration of the seed alone is no longer adequate, "However, it is the responsibility of the institution to verify that this calibration is correct. the institution should compare the manufacturer's stated value with the institution's standard."2

1. "Verification of manufacturer-supplied 125I and 103Pd air-kerma strengths". Mellenberg & Kline; Medical Physics. 22(9):1495-1497, 1995.
2. "Comprehensive QA for radiation oncology: Report of AAPM Radiation Therapy Committee Task Group 40". Medical Physics. 21(4):581-618, 1994.

Rapid Strand, Metastron, and OncoSeed are trademarks of Amersham plc.

If you are interested in any of the products mentioned here, please fill out an Enquiry Form or a Quotation Request Form, so that we may promptly respond to your request.


Please contact Colin Walters at cwalters@seedos.com if you would like further  information or you have questions

or comments about this web site.
SeeDOS Ltd, 26, The Maltings,Leighton Buzzard, Bedfordshire LU7 4BS, United Kingdom
Tel: +44 1525 850 670  • Fax: +44 1525 850 685