Dose perturbation and inhomogeneity of multi-arrays of 125I seed-loaded stent for treatment of portal vein tumor thrombosis.
Phys Med
; 66: 1-7, 2019 Oct.
Article
in En
| MEDLINE
| ID: mdl-31563726
ABSTRACT
PURPOSE:
To investigate the dosimetry of 125I seed-loaded stent system currently used for an adjuvant treatment of portal vein tumor thrombosis (PVTT).METHODS:
The stent system consisted of an inner metallic stent and outer seed-loaded capsules. Four arrays of 125I seeds were attached longitudinally to the outer surface of the stent at 90° separation. 145â¯Gy was prescribed at 5â¯mm from the axes of seed-arrays. For the geometries of the 4-array, and potential 6- and 8-array configurations, treatment planning system (TPS) and Monte Carlo (MC) calculations were performed to evaluate 3D dose distributions and dosimetric impact of the metallic stent.RESULTS:
The MC simulations indicated the metallic stent reduced a dose to the prescription points by over 10%, compared to the water-based TPS results. The total activity calculated by the water-based TPS to deliver the prescription dose should compensate for this amount of reduction. The MC- and TPS-calculated doses normalized to the prescription points for the current configuration were in agreements within 4.3% on a cylindrical surface along 5â¯mm from the axes of seed-arrays. The longitudinal underdosage worsened as approaching the edge of arrays, and ranged from 2.8% to 25.5%. The angular underdosage between neighboring arrays was 2.1%-8.9%.CONCLUSIONS:
With this compensation and a special care of near-edge underdosage, the current 4-array system can provide adequate dose coverage for treatment of PVTT. Further dosimetric homogeneity can be achieved using 6-or 8-array configurations.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Portal Vein
/
Radiation Dosage
/
Thrombosis
/
Stents
/
Iodine Radioisotopes
Type of study:
Health_economic_evaluation
Language:
En
Journal:
Phys Med
Journal subject:
BIOFISICA
/
BIOLOGIA
/
MEDICINA
Year:
2019
Document type:
Article
Affiliation country:
South Korea