IAEA Training Material on Radiation Protection in Radiotherapy
- Slides: 52
IAEA Training Material on Radiation Protection in Radiotherapy Part 6 Brachytherapy Lecture 2 (cont. ): Brachytherapy Techniques Part 6, lecture 2 (cont. ): Brachytherapy techniques
Brachytherapy l l l Very flexible radiotherapy delivery Allows a variety of different approaches, creating the opportunity for special and highly customized techniques Not only used for malignant disease (=cancer) Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 2
Special techniques A. Prostate seed implants B. Endovascular brachytherapy C. Ophthalmic applicators D. Other special techniques Both point B and C are examples for the use of brachytherapy for non-oncological purposes Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 3
A. 125 -I seeds for prostate implants Relatively new technique l Indicated for localized early stage prostate cancer l Permanent implant l Preferred by many patients as it only requires one day in hospital l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 4
Treatment Options for prostate cancer l l Seed Implant Monotherapy (about 144 Gy) EBT (45 Gy) + Implant Boost n n l l Seed Implant (108 Gy) HDR Implant (16. 5 Gy/3) External Beam only (65 -84 Gy) Surgery (Radical Prostatectomy) è This all could be combined with hormones and/or chemotherapy Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 5
Implant schematic Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 6
A typical implant l l l Deliver 144 Gy to entire prostate gland Approximately 100 I-125 seeds (25 needles) Needles are guided by ultrasound a template grid Pre-planned needle positions to give even dose but avoid pubic arch Minimise rectal dose and avoid urethra overdose CT after 3 weeks for post-planning Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 7
Isotopes in use l Iodine 125 - 144 Gy - I-125 n Half Life = 60 days n Energy = 28 ke. V n TVL lead = 0. 08 mm l Palladium 103 - 108 Gy - Pd -103 n Half Life = 17 days - dose rate about 2. 5 times larger than for 125 -I n Energy = 22 ke. V n TVL lead = 0. 05 mm Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 8
Prostate Implant Process Ultrasound Volume Study l Pre-planning: what would be ideal l Ordering I-125 seeds and calibration l Needle loading l Ultrasound guided Implantation l CT post-planning a couple of weeks after: what has been achieved? l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 9
Pre-planning l l l Several different systems possible Provides guidance for approach, data on number of sources required and loading of needles Avoid central column to spare urethra Cover target laterally Conform to posterior border (spare rectum) Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 11
Preparation of seeds l l l Ordering planned number of seeds + some spares Checking seed activity Sorting and loading seeds into needles Seed alignment tray Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 12
Implant needle loaded with seeds and spacers Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 13
Implant template Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 14
Implant jig Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 15
Ultrasound Guided Implant Procedure Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 16
X-ray of implanted seed Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 17
CT post-planning after 4 weeks Swelling is gone - CT provides true three dimensional information on the implant geometry Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 18
Post CT planning = establishing the actual dose distribution Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 19
Quality of Implant Depends on seed placement l Seeds may migrate with time l If large dose inhomogeneities exist, the critical cold spots can be boosted by either placing more seeds in the prostate or using external beam radiotherapy l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 21
Notes on prostate seed implants l A similar technique is available using 103 -Pd seeds n 103 -Pd has a shorter half life and therefore a higher activity is implanted n Otherwise the rules an considerations are similar to 125 -I seed implants Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 22
2. Endovascular brachytherapy Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 23
The issue: re-stenosis After opening of a blocked blood vessel there is a high (60%+) likelihood that the vessel is blocked again: Re-stenosis l Radiation is a proven agent to prevent growth of cells l Radiation has been shown to be effective in preventing re-stenosis l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 24
Dilation of blood vessels l Mostly for cardiac vessels but also possible in some extremities Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 25
Endovascular irradiation l l Mostly for cardiac vessels but also possible in some extremities Many different systems and isotopes in use Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 26
Isotopes for endovascular brachytherapy l Gamma sources: 192 -Ir n the first source which has been clinically used (Terstein et al. N Eng J Med 1996) Beta sources: 32 -P, 90 -Sr/Y, 188 -Rh (Rhenium) l Activity around 1 Ci l Dose calculation Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 27
Beta sources l Most commercial systems use them because: n finite range in tissues n less radiation safety issues in the operating theatre n smaller, hand held units possible for use in cardiac theatres l Potential problem: may not reach all cells of interest Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 28
The Beta-Cath™ System (Novoste) Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 29
Guidant system l Radiation Protection in Radiotherapy Employs centering catheter to ensure source is always in the center of the vessel Part 6, lecture 2 (cont. ): Brachytherapy techniques 30
Radiation safety in theatre l Application of radiation in theatre: n n n time is of the essence - planning in situ shielding would be difficult physicists must be present Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 31
Irradiation of extended lesions Use “Radiation Source Train” l Stepping source process to cover desired length l 100 % Longitudinal Dose Distribution 50 % 0% L/2 Radiation Protection in Radiotherapy L/2 Part 6, lecture 2 (cont. ): Brachytherapy techniques 32
Angiographic Appearance of PDL in Delivery Catheter Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 33
Radiation Source Train: Dose Profile at 2 mm 40 mm Radiation Source Train (RST) Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 34
Radioactive stents l l Stents are used to keep blood vessels open Can be impregnated with radioactive material (typically 32 -P) to help prevention of restenosis Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 35
C. Ophthalmic applicators l l l Treatment of pterigiums and corneal vasculations, a nononcological application of radiotherapy Use of beta sources mostly 90 -Sr/Y Typical activity 40 to 200 MBq (10 -50 m. Ci) Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 36
Ophthalmic applicators Activity covered by thin plated gold or platinum l Curvature to fit the ball of the eye l Diameter 12 to 18 mm l Activity may only be applied to parts of the applicator l Typical treatment time for several Gy less than 1 min l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 37
Decay scheme of 90 Sr / 90 Y ß 0. 54 Me. V, T 1/2 = 28. 5 yrs 90 Y ß 2. 25 Me. V, T 1/2 = 64 hrs 90 Zr Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 38
Dept Dose Curve of 90 Sr in H 2 O Finite treatment depth Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 39
Issues with ophthalmic applicators - dosimetry Dosimetry difficult due to short range of particles l Dose uncertainty > 10% l Short treatment times taken from lookup tables - potential for mistakes l Documentation often less than complete l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 40
Other guidance and issues l l l Never point source at someone - range in tissue <1 cm, but in air > 1 m!!! Radiation typically used by non radiotherapy staff (eye specialists, nurses) - training required Sterilisation/cleaning - must not affect integrity of the cover Regular check of homogenous distribution of activity required Wipe tests required Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 41
D. Other specialized brachytherapy applications l Intra-operative brachytherapy n Use of radiation in operating theatre n Useful for incomplete surgical removal of cancer n Allows highly topical application of radiation n If surgery is followed by radiotherapy, one is “ 10 Gy ahead” in tumor dose Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 42
Intra-operative brachytherapy l In practice not often used because n not always possible to predict if radiation will be needed during the operation n requires radiation oncologist to be available n radiation safety issues s shielded theatre costly patient must be left alone during irradiation even if less than 5 min this is a risk due to anesthetics Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 43
A note on radiation protection l Many specialized brachytherapy applications are performed outside of a conventional radiotherapy department - this requires consideration of: n n n l training shielding communication Excellent planning and documentation is required Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 44
Intra-operative brachytherapy l l l In principle possible Treatment units (must be HDR) available Applicators are available Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 45
Summary I l l Brachytherapy is a highly customized and flexible treatment modality Quality of treatment depends on operator skills From a radiation protection point of view remote afterloading is most desirable: A variety of equipment is available to deliver remote afterloading brachytherapy HDR brachytherapy is the most common delivery mode nowadays. Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 46
Summary II l l l 125 -I seed implants are a alternative for radiotherapy of early prostate cancer Endovascular brachytherapy is one of an increasing number of non-oncological applications of brachytherapy There may be radiation safety issues if specialized brachytherapy procedures are performed outside of a radiotherapy department as staff not used to working with ionizing radiation is using radioisotopes Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 47
References l l Nath et al. Intravascular brachytherapy physics. AAPM TG 60 report. Med. Phys. 26 (1999) 119 -152 Waksman R and Serray P: Handbook of vascular brachytherapy (London: Martin Dunitz) 1998 Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 48
Any questions? Part 6, lecture 2 (cont. ): Brachytherapy techniques
Question: Please list some radiation safety issues when using 90 -Sr/Y applicators for ophthalmic treatments - you should consider the appendices of BSS to classify them. . . Part 6, lecture 2 (cont. ): Brachytherapy techniques
Radiation Safety Issues when using 90 -Sr/Y applicators l Occupational exposure: n cleaning n sterilization n contamination n handling of sources by non-radiotherapy staff Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 51
Radiation Safety Issues when using 90 -Sr/Y applicators l Medical exposure: n dosimetry difficult n contamination from damaged applicator n over/under exposure of the eye of the patient n irradiation of other areas of the patient Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 52
Radiation Safety Issues when using 90 -Sr/Y applicators l Public exposure: n transport of the sources n security of sources n storage and disposal Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 53
Acknowledgement Craig Lewis, London Regional Cancer Centre l Mamoon Haque, RPA Hospital l Radiation Protection in Radiotherapy Part 6, lecture 2 (cont. ): Brachytherapy techniques 54
- Wedge factor radiotherapy
- Ssd and sad technique in radiotherapy
- Radiotherapy
- Pterigiums
- Radiotherapy
- Siemens radiotherapy
- Radiation protection officer qualifications
- Barium sulphate board for radiation protection
- Cardinal principles of radiation protection
- National radiation protection authority namibia
- Ssr5
- Saris iaea
- Iaea livechart
- Pcmf
- Iaea gsr part 4
- Rtc protective film
- Iaea
- Iaea
- Stefano monti iaea
- Iaea
- Iaea
- Iaea
- Iaea
- Iaea
- Gsr part 7
- Iaea pcmf
- Film badge
- Iaea
- Gsr part 2
- Who trains employees that work on scaffolds
- Fall protection training outline
- Child protection training materials
- Child protection awareness training
- Geometrical symbols
- Material yield variance formula
- Non material culture examples
- What is real culture
- Material and non material culture examples
- Useful but harmful materials
- Bullying and harassment training resources
- Disclaimer for training material
- Disclaimer for training material
- Disclaimer for training material
- Team building workshop modules
- Training material development
- Ladder types ratings
- Open source six sigma training material
- Disclaimer for training material
- Counterfeit material awareness training
- Gmp training for employees
- Icpc training material
- Training is expensive without training it is more expensive
- Perbedaan on the job training dan off the job training