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

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 Bashar.Al-Qaisieh@leedsth.nhs.uk

Template, Needles, Ruler and Tools Bashar.Al-Qaisieh@leedsth.nhs.uk

QA for HDR Brachytherapy Besides the typical QA procedures established for common HDR treatments, we need to implement additional ones Bashar.Al-Qaisieh@leedsth.nhs.uk

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 • Bashar.Al-Qaisieh@leedsth.nhs.uk

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 Bashar.Al-Qaisieh@leedsth.nhs.uk

Pre-Treatment QA Bashar.Al-Qaisieh@leedsth.nhs.uk

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 Bashar.Al-Qaisieh@leedsth.nhs.uk

Independent Calculation Check- TRAK Example Bashar.Al-Qaisieh@leedsth.nhs.uk

Plan Record and Catheter QA • Needle template position and needle order • Free length measurements • Base measurement • Probe position Bashar.Al-Qaisieh@leedsth.nhs.uk

Plan Record and Catheter QA Bashar.Al-Qaisieh@leedsth.nhs.uk

Template Calibration Ultrasound Template Guidance Template TPS Template Bashar.Al-Qaisieh@leedsth.nhs.uk

Template Calibration Bashar.Al-Qaisieh@leedsth.nhs.uk

Volume Test • Check volume captured from US is similar to the volume contoured on planning system Bashar.Al-Qaisieh@leedsth.nhs.uk

Dose Point Calculation Air Kerma Strength + Dwell Times → Dose at point (s) Expected Dose Oncentra Prostate Dose / Gy Point / 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: Bashar.Al-Qaisieh@leedsth.nhs.uk

Optimisation Check Air Kerma Strength + Prescribed dose to PTV → Dwell Times Opt e.g. Catheter Dwell time / s Oncentra Prostate dwell time / s 1 43.09 2 30.01 3 56.44 4 34.18 Performed by: Bashar.Al-Qaisieh@leedsth.nhs.uk

DVH 3.0cm 4 3 = 113 . 1 V = π r cc 3 Bashar.Al-Qaisieh@leedsth.nhs.uk

Isodose/DVH check This test uses DVH values to verify the dose volume calculation of the planning system. e.g. Parameter Value Oncentra Prostate value D90 5.9740 Gy 235.9343 cm 3 V100 151.8108 cm 3 V150 108.0353 cm 3 V200 Performed by: Bashar.Al-Qaisieh@leedsth.nhs.uk

Data Transfer Check To verify accurate delivery of plan to TCS Bashar.Al-Qaisieh@leedsth.nhs.uk

Data transfer check Bashar.Al-Qaisieh@leedsth.nhs.uk

3D Ultrasound • Better visibility • Improved treatment planning • Reproducibility Bashar.Al-Qaisieh@leedsth.nhs.uk

Image transfer check (Ultrasound phantom) 1cm 1.4cm Bashar.Al-Qaisieh@leedsth.nhs.uk

Image transfer check (Ultrasound phantom) Ideal value Tolerance Parameter Correct value? (Tick) Vertical spacing 1.0 cm 0.1 cm Diagonal spacing 1.4 cm 0.1 cm 3.6 cm 3 1.0 cm 3 Small volume 8.8 cm 3 1.0 cm 3 Medium volume 20.4 cm 3 1.0 cm 3 Large volume Performed by: Bashar.Al-Qaisieh@leedsth.nhs.uk

Needles Commissioning Dead end and first DP Bashar.Al-Qaisieh@leedsth.nhs.uk

US Image Geometry and Catheter Reconstruction Bashar.Al-Qaisieh@leedsth.nhs.uk

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 Bashar.Al-Qaisieh@leedsth.nhs.uk

Thank You Bashar.Al-Qaisieh@leedsth.nhs.uk