Real Time Image Guided HDR Brachytherapy for Prostate Cancer. - - PDF document

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Real Time Image Guided HDR Brachytherapy for Prostate Cancer. - - PDF document

Mar 14, 2024 369 likes •668 views

Real Time Image Guided HDR Brachytherapy for Prostate Cancer. Equipment and Quality Assurance Bashar Al-Qaisieh Equipment Bashar.Al-Qaisieh@leedsth.nhs.uk Theatre Bed Bashar.Al-Qaisieh@leedsth.nhs.uk Stepper Unit

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Real Time Image Guided HDR Brachytherapy for Prostate Cancer. Equipment and Quality Assurance

Bashar Al-Qaisieh

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Bashar.Al-Qaisieh@leedsth.nhs.uk

Equipment

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Theatre Bed

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Stepper Unit

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Template, Needles, Ruler and Tools

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QA for HDR Brachytherapy

Besides the typical QA procedures established for common HDR treatments, we need to implement additional ones

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Prostate HDR QA Overview

  • Pre-Treatment Quality Assurance Checks
  • Independent physics check
  • Pre-Treatment needle free length check
  • TPS Commissioning, Source change, Software and

hardware update/upgrade.

  • Dose point calculation

TG43 algorithm test Optimisation consistency test

  • Isodose check
  • DVH check
  • Data transfer check
  • Image transfer check (Ultrasound phantom)

Image distortion test Volume consistency test

  • Applicator Commissioning
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Pre-Treatment QA

  • Objective:

Test the integrity of the treatment planning system and check the current source data file and equipment setup.

  • Procedure

US probe mark, US & TCS connectivity, verify stepper encoder, AKS, point dose calculation, isodose plot..etc

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Pre-Treatment QA

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Independent Calculation Check- Point Dose

  • Calculation base on TG43-U1 1D formalism (point source

approximation)

  • OCP Calculation based full 2D TG43-U1 formalism (line source)
  • TG43 data from Daskalov et al, Med Phys 25(11) Nov 98, 2200-2207

Example

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Independent Calculation Check- TRAK

Example

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Plan Record and Catheter QA

  • Needle template

position and needle

  • rder
  • Free length

measurements

  • Base measurement
  • Probe position
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Plan Record and Catheter QA

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Template Calibration

Ultrasound Template TPS Template Guidance Template

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Template Calibration

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Volume Test

  • Check volume

captured from US is similar to the volume contoured on planning system

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Dose Point Calculation

Air Kerma Strength + Dwell Times → Dose at point (s)

Oncentra Prostate Dose / Gy Point Expected Dose / Gy 1 32.3233 2 32.2828 3 31.6897 4 18.9138 5 19.0976 6 48.9164 7 48.8740 8 8.3312 9 8.2626 Performed by:

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Optimisation Check

Air Kerma Strength + Prescribed dose to PTV → Dwell Times

Opt

Oncentra Prostate dwell time / s Catheter Dwell time / s 1 43.09 2 30.01 3 56.44 4 34.18 Performed by:

e.g.

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DVH

cc r V 1 . 113 3 4

3 =

= π

3.0cm

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Isodose/DVH check

This test uses DVH values to verify the dose volume calculation of the planning system.

Oncentra Prostate value Parameter Value D90 5.9740 Gy V100 235.9343 cm3 V150 151.8108 cm3 V200 108.0353 cm3 Performed by:

e.g.

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Data Transfer Check

To verify accurate delivery of plan to TCS

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Data transfer check

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3D Ultrasound

  • Better visibility
  • Improved treatment

planning

  • Reproducibility
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Image transfer check (Ultrasound phantom)

1.4cm 1cm

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Image transfer check (Ultrasound phantom)

Correct value? (Tick) Parameter Ideal value Tolerance Vertical spacing 1.0 cm 0.1 cm Diagonal spacing 1.4 cm 0.1 cm Small volume 3.6 cm3 1.0 cm3 Medium volume 8.8 cm3 1.0 cm3 Large volume 20.4 cm3 1.0 cm3 Performed by:

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Needles Commissioning

Dead end and first DP

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US Image Geometry and Catheter Reconstruction

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Ultrasound Machine Check

  • Assurance of Mechanical and Electrical

Safety

  • Distance Accuracy (vertical and horizontal)
  • Contrast and Brightness (Gray bar

visualization)

  • Image Uniformity
  • Penetration
  • Lateral Resolution
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Thank You