Related Experiment Video
Updated: Jan 27, 2026

Patient-derived Orthotopic Xenograft Models for Human Urothelial Cell Carcinoma and Colorectal Cancer Tumor Growth and Spontaneous Metastasis
Published on: May 12, 2019
Optimization of HDRBT boost dose delivery for patients with rectal cancer
Slobodan Devic1, Hamed Bekerat2, Aurelie Garant3
1Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Oncology Department, McGill University, Montreal, Quebec, Canada; Segal Cancer Centre, Jewish General Hospital, McGill University, Montréal, Quebec, Canada.
Purpose:
We describe methods to improve dose delivery for patients with rectal cancer receiving boost brachytherapy after external beam radiotherapy.
Methods And Materials:
Patients with rectal cancer who were ineligible or refusing surgery are treated with external beam radiotherapy and subsequently with three weekly image-guided volume-adapted high-dose-rate brachytherapy boosts of 10 Gy to the residual clinical target volume, for a total of 30 Gy in three fractions. Tungsten shielding placed at the center of intracavitary mold applicator and double-balloon technique was used to improve dose conformity to the target.
Results:
Our results show that the use of tungsten shield and double balloon reduces the dose gradient within the target volume to receive the prescription boost dose of 10 Gy from maximum dose of 60 Gy down to 20 Gy.
Conclusions:
We outlined two methods for achieving higher high-dose-rate brachytherapy dose conformity using the tungsten shielding rods (to spare contralateral healthy tissues) and double-balloon technique (to decrease dose gradient within the target to minimize dose to the proximal mucosa).
Related Concept Videos
Drug Dosing: Geriatric Patients
Drug Dosing: Obese Patients
Assessing Body Temperature - Rectal
Follow these steps for rectal temperature assessment:
Step 1: Perform hand hygiene and don clean gloves to prevent cross-infection.
Step 2: Position the patient in a side-lying position to better visualize the rectal...
Dose Size and Dosing Frequency: Determination Methods
Determination of Multiple Dosing Parameters: Loading and Maintenance Doses
Rational Dosage Regimen: Maintenance Dose and Loading Dose
In most cases, drugs are administered repetitively or infused continuously to maintain a steady-state concentration in the body. At a steady...

