Immobilization Devices.pptx ;DR YAMINI ; RADIOTHERAPY ; AIIMS GORAKHPUR

RADIOTHERAPY

1. Immobilization Devices Dr. Yamini Bisht Junior Resident Department of Radiotherapy AIIMS Gorakhpur

2. Aim of immobilisation Accuracy of treatment Protection of normal tissue Decrease treatment related complication Reduce intrafraction and interfraction error Goal : reproduce the position at the time of simulation as best as possible

3. Causes of field placement error Fidgeting Uncomfortable or anxious Internal movement of organs: Breathing Swallowing Peristalsis

4. Advantages of immobilisation devices Decrease the time needed for daily setup Allow setup marks to be made directly on the device Confer dosimetric advantages in t/t planning

5. Desirable characteristics of an immobilisation device Lightweight Strong and durable Made of materials that minimally affect the MV t/t beam Do not cause imaging artifacts

6. Simple immobilisation devices

7. Uses Supine position treatment: a wedge or roll underneath the knee can help to reduce stress on the lower back Arm down positioning: A ring for the patient to grip can increase comfort Lung and liver treatments : Grip for positioning the patient with arms above the head Head and neck patients: Strap to pull that shoulder down out of the treatment fiend Headrest : To elevate the head and reduce strain on neck

8. Immobilisation features of a CT simulator T-bar

9. Advantages Indexing system: Improves reproduce ability and decrease the amount of time to set up a patient Flat couch: reproduces the couch geometry of the treatment unit Vacuum lock bag : help support patients arm In room laser system : provides external reference point that correlate to the internal reference point location

10. Head and neck immobilisation devices Thermoplastic masks Replaced traditional plaster casting methods Heated to approximately 70°C in a water bath or a dry heat oven Material: Cellulose acetate/ Polyvinyl chloride Thickness: 1.6-4.2mm Becomes malleable Can be stretched and shaped to conform to the patient’s face, head, and neck Setup marks can be made directly on the mask

11. Head only (3 point cast) Head and shoulder (5 point cast) For prone and lateral positions Storage area with water bath

12. Drawbacks Requires more equipment and space Shrink as they cool Lead to error Uncomfortable for the patient Requires re-simulation Solution: BionixRT has made Klarity Green material: reduce shrinkage and increased rigidity

13. Bite blocks Not well tolerated by patients Can cause claustrophobia Elekta: HeadFIX Carbon fiber design Drawbacks : a high-level of patient compliance Not suitable for patients with poor dentition or edentulism Custom bite block : to separate the tongue from the roof of mouth ( sinus/nasal cavity tumours)

14. Body conformal immobilisation devices Alpha Cradle Foaming agents conforms to patient’s body 10-15 mins Vacuum lock bags Plastic mini spheres (Polystyrene confetti) Retains shape for 6 weeks Reusable and require less time Reinflated and remolded

15. Elekta BodyFIX Dual vacuum system Pressure 600 mbar Better reproducibility Abdominal compression: decrease respiratory movements

16. Prone positioning for Pelvic and Breast Treatments

17. DOSIMETRIC EFFECTS OF IMMOBILIZATION DEVICES Electrons liberated Increased surface dose Bolusing effect More frequent skin reactions

18. STEREOTACTIC IMMOBILIZATION AND STABILIZATION Invasive Intracranial Immobilization devices Driven directly into the skull Rigid immobilization Accuracy <1mm Leksell Stereotactic Coordinate Frame G Disadvantage : non relocatable , therefore requires removal on same day

19. Noninvasive Cranial Immobilization Placing of screws Relocatable Stereoadapter 5000 Elekta eXtend frame system Mean intrafraction motion: 0.4 ± 0.3 mm Disadvantage : Bleeding and Infections Accuracy measurement: RCT (repeat CT)

20. Brainlab Mask Daily Xray image guidance U shaped frame Two vertical posts Three peice thermoplastic masks Bite block attachment (optional) Localizer device Mean intrafraction shift of 0.7 ± 0.5 mm

21. Extracranial Immobilization Devices Extracranial SBRT Body Pro-Lok from CIVCO Medical Solutions Bionix Omni V SBRT positioning system Elekta Stereotactic Body Frame Indexing along the entire length Mean localization errors of 0.9 ± 3.1 mm, 1.2 ± 5.5 mm, and 6.5 ± 2.6 mm in the x, y, and z dimensions

22. Internal Motion Management Management of respiratory motion Deep inspiration breath hold ( DIBH ) Active breathing control Respiratory gating Real-time tumor tracking Abdominal compression devices

23. Deep Inspiration Breath Hold Treatments for Breast Radiotherapy Left sided breast Time: min 30 sec Cardiac sparing As the lung inflate, heart moves away from chest wall Surface imaging OSI (OPTICAL SURFACE IMAGING)

24. OPTICAL SURFACE IMAGING Monitoring patient positioning Intrafraction monitoring Surface-Guided Radiation Therapy ( SGRT ) or Surface Image-Guided Radiation Therapy ( SIGRT ) Used to detect external motion or even track breathing

25. Intracranial Stereotactic Radiosurgery Requires uncovered skin Can’t use conventional masks Open Masks Increased patient comfort Continuous tracking Real-time, uninterrupted monitoring of the patient

26. IMMOBILIZATION METHODS IN BRACHYTHERAPY Not just immobilization of applicator Patient movement can cause applicator displacement Immobilisation for Genitourinary Treatment Ca Prostate and Ca Cervix Image-guided brachytherapy (IGBT) Stabilising needles Aquaplast during MR imaging Lateral decubitus position

27. Integrated Brachytherapy Unit (IBU) Scan, plan, and treat in a single room In-room cone-beam CT system IGBT (Image guided Brachytherapy) suite CT on rails for in-room patient imaging and 3D treatment planning. Scanner itself translates over the patient

28. Immobilization for Breast Brachytherapy Implanted catheters or balloons 5 days PARTIAL BREAST IRRADIATION ( PBI ) Treat the lumpectomy cavity (vs whole breast irradiation) Breast bridges Makes placement of catheter more reproducible

29. TOTAL BODY IRRADIATION IMMOBILIZATION TBI stand Distance: 5m Gantry at a horizontal angle: 90 or 270 degrees Disadvantage : Storage space

30. IMMOBILIZATION STRATEGIES FOR INTRAOPERATIVE RADIOTHERAPY Intraoperative radiotherapy (IORT) Single high-dose fraction of radiation is delivered directly to the tumor bed immediately following surgical resection Partial Breast Irradiation Advantages Lower rates of toxicity Enhanced patient convenience Both used as sole therapy and Upfront boost to EBRT

31. Linear accelerator based delivery Collimator Cone Placed on target tissue Then aligned with electron beam Hard Docking: linac must be rigidly connected to cone Via Rigid arm clamped to the surgical table Mobetron System: Soft docking : Internal laser-guided system uses a mirror on the top of the cone to precisely align the radiation beam

32. Thank You