CT-validation of Ultrasound Based Planning for High Dose Rate (HDR) Prostate Brachytherapy Using Vitesse

British Columbia Cancer Agency20 enrolled

Overview

High Dose Rate (HDR) temporary prostate brachytherapy offers a precise form of dose escalation for prostate cancer. Needles are placed, the position is confirmed and treatment is delivered. Previously High Dose Rate prostate brachytherapy was performed under TransRectal UltraSound (TRUS) guidance but planned with Computed Tomography (CT) imaging which introduced a source of error through needle displacement while transporting and repositioning patient. Recently Varian has introduced a one-step procedure where both implant and planning are based on UltraSound imaging and performed without patient repositioning. This planning system is approved by Health Canada and is commercially available. This study will use High Dose Rate brachytherapy to treat 20 men. Treatment will be planned with TransRectal UltraSound and validated using Computed Tomography imaging.

Twenty men with intermediate risk prostate cancer, suitable for the combination of external beam radiotherapy and High Dose Rate brachytherapy will be entered in this study. High Dose Rate brachytherapy will be performed using TransRectal UltraSound guidance and then planned using both cone-beam Computed Tomography and TransRectal UltraSound. Planning by Computed Tomography is to check the reliability and reproducibility of UltraSound imaging to correctly identify the needle positions. Correct needle localization is essential because this is the basis for determining source dwell positions, dose calculation and dose optimization.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Prostate Cancer

Eligibility

Sex: MALEMin age: 45 YearsMax age: 80 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Patients must have histologically proven adenocarcinoma of the prostate. 2. Patients must have intermediate risk prostate cancer. (Clinical stage ≤ T2c, Gleason score = 7 and initial prostate specific antigen (iPSA) ≤ 20, or Gleason score ≤ 6 and iPSA \> 10 and ≤ 20. 3. Patients must be fit for general or spinal anaesthetic. 4. Patients must have an estimated life expectancy of at least 10 years. 5. Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2. 6. Patients must have no contraindications to interstitial prostate brachytherapy. 7. Patients on coumadin therapy must be able to stop therapy safely for at least 7 days. Exclusion Criteria: * Men not able to fully understand the trial and the informed consent document * Men suffering from claustrophobia and unable to have a Computed Tomography scan * Men not wishing to have a cone-beam Computed Tomography scan following the insertion of the High Dose Rate brachytherapy needles to verify the accuracy of the treatment plan * Men who cannot safely discontinue blood thinners for a few days.

Outcomes

Primary Outcomes

Accuracy of Needle Tip Identification on TransRectal UltraSound Compared to Computed Tomography

Precise location of the tip of each needle in 3-dimensional space relative to the prostate determines the pattern of dose delivery. Inaccuracies in needle tip location may lead to differences detected between UltraSound(US)-based and Computed Tomography (CT)-based plans.The distance of the needle tip (as identified on either CT images or US images) protruding beyond the template was measured in mm. The template acted as a fixed reference point as it was locked into the stabilizer/stepper apparatus. The 2 protrusion readings for each needle tip were compared, the difference recorded in mm, and categorized as \< 1 mm, 1-2 mm, 2-3 mm and \> 3 mm.

Time frame: Treatment was planned and delivered based on ultrasound identification of needles and needle tips relative to prostate. All measurements and comparisons of measurements pertain to the day of the procedure.