ESTRO 2024 - Abstract Book

S173

Brachytherapy - GI, paediatric, miscellaneous

ESTRO 2024

GAFchromic film dosimetry

MOSFET dosimetry Measuring point on the right (Gy)

Measurement Number

Measuring point on the right (Gy)

Measuring

point

Measuring point on the left (Gy)

on the left (Gy)

1 2 3 4 5 6

3.511 3.268 4.866 3.628 3.592 3.457 3.720 3.551

3.369 3.167 3.750 2.584 3.200 3.190 3.210 3,195

3.04 3.04 3.13 3.20 3.14 3.09

3.00 3.00 2.97 3.05 2.96 2.89

Mean

3.106 3.110

2,978 2.985

Median

Conclusion:

In conclusion, it is known that there are many factors affecting radiation dosimetry, and the uncertainty of the measurement point is also an important factor. Therefore, studies that use different measurement techniques and increased sample size are needed to increase accuracy and make statistical comparisons.

Keywords: Rectal cancer, silicone material, multichannel

334

Digital Poster

Study of diffusing alpha-particle emitting daughters of the Alpha-DaRT sources through animal models

Mélodie N Cyr 1 , Naim Chabaytah 1 , Joud Babik 1 , Behnaz Behmand 1 , Mirta Dumancic 1,2 , Joanna Li 1,2 , Guillaume St Jean 3 , Shirin A Enger 1,4,2 1 McGill University, Medical Physics Unit, Department of Oncology, Faculty of Medicine, Montreal, QC, Canada. 2 Jewish General Hospital, Lady Davis Institute for Medical Research, Montreal, QC, Canada. 3 University of Montreal, Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Montreal, QC, Canada. 4 McGill University, Research Institute of McGill University Health Center, Montreal, QC, Canada

Purpose/Objective:

Interstitial sources deliver a prescribed dose to the tumor while minimizing damage to surrounding healthy tissue. Recently, a 224 Ra-based interstitial treatment modality relying on diffusing alpha-emitting radiation therapy (Alpha DaRT) has been introduced. Implantable sources impregnated with activity of 3 µCi of 224 Ra are placed inside solid tumors, where short-lived alpha-particle emitting atoms are released in the decay chain of 224 Ra. Although the range of alpha particles released in the decay process is a couple of cell diameters, these atoms diffuse inside the tumor, contributing to a high-dose region up to ~3 mm from the source [1] [2]. However, the scaling parameter dictating the distance these alpha-emitting atoms travel from the source, i.e., diffusion length, is not well known for several cancer types. The currently used diffusion lengths are based on pre-clinical studies through subcutaneous animal models and a couple of orthotopic models [3] [4] [5] [6] [7].