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Brachytherapy Final

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    • 1.
      • DR. MANOJ KUMAR B
      • MODERATOR:PROF. S.C. SHARMA
      • DEPTT. OF RADIOTHERAPY AND ONCOLOGY
      • PGIMER,CHANDIGARH
      BRACHYTHERAPY PRINCIPLE AND METHODS
    • 2. BRACHYTHERAPY
      • Type of radiation treatment in which radioactive sources are arranged in such a fashion that radiation is delivered to the tumor at a short distance by interstitial, intracavitary or surface application.
    • 3. CLINICAL ADVANTAGES
      • High biological efficacy
      • Rapid dose fall-off
      • High tolerance
      • Tolerable acute intense reaction
      • Decreased risk of tumor population
      • High control rate
      • Better cosmesis
      • Minimal radiation morbidity
      • Day care procedure
    • 4. LIMITATIONS & DISADVANTAGES
      • Difficult for inaccessible regions
      • Limited for small tumors (T 1 _T 2 )
      • Invasive procedures, require GA
      • Higher dose inhomogeneity
      • Greater conformation –small errors in placement of sources lead to extreme changes from the intended dose distribution
      • Radioactive hazards (not now)
      • Costly
    • 5. SELECTION CRITERIA
      • Easily accessible lesions
      • Early stage diseases (Ideal implant ≤ 5 cm)
      • Well localized tumor to organ of origin
      • No nodal or distant metastases
      • No local infections or inflammation
      • Favorable histology- mod. diff. i.e. SCC
      • Non DM / HTN
      • Proliferative/ ulcerative lesions preferred
    • 6. INDICATIONS
      • RADICAL RADIATION
        • Skin malignancies- BCC, SCC
        • Head & neck cancers
        • Ca cx
        • Ca prostate
      • BOOST AFTER EXT.RT±CCT
        • Head & neck cancers
        • Ca Breast
        • Esophagus
        • Anal canal
    • 7. INDICATIONS...
      • PERIOPERTIVE
        • STS
        • Ca Breast
      • POSTOP
        • Ca Endometrium
        • Ca cx
        • Ca Breast
      • PALLIATIVE
        • Bronchogenic Ca
        • Biliary duct malignancy
        • Ca Esophagus
        • Recurrent tumors
      • BENIGN
        • Keloids / Pterygium
      • OTHERS
        • Endovascular/Rad. stent
    • 8. CLASSIFICATION Classification Schemes Positioning of Radionuclide Dose rate of irradiation Duration of irradiation Loading pattern
    • 9. CLASSIFICATION
      • SURGICAL APPROACH / POSITIONING
        • SOURCE IN TUMOR
          • INTERSTITIAL
          • INTRACAVITARY
          • INTRALUMINAL
          • ENDOVASCULAR
        • SOURCE IN CONTACT BUT SUPERFICIAL
          • SURFACE BRACHYTHERAPY/ MOULAGE
      • DURATION OF IRRADIATION
        • TEMPORARY-Cs 137 ,Ir 192
        • PERMANENT-I 125 ,Au 198
    • 10. DOSE RATE(ICRU 38)
      • LOW DOSE RATE (LDR)
        • 0.4-2 Gy/hr
        • Bed confinement
        • LDR A/L : Cs 137
      • MEDIUM DOSE RATE (MDR)
        • 2-12 Gy/hr
      • HIGH DOSE RATE (HDR)
        • > 12 Gy/hr
      • ULTRA LOW DOSE RATE
        • 0.01-0.3 Gy/hr
      • ROUGHLY
        • LDR – 10 Gy/day
        • MDR -10 Gy/hr
        • HDR – 10 Gy/min
    • 11. ADVANTAGES
      • LDR
      • HDR
      • Predictable clinical effects
      • Superior radiobiological role
      • Less morbidity, control is best
      • Well practised since long
      • Minimum intersession variability in dose distribution
      • SHORT T/T TIME
        • Geometry well maintained
        • Better patient compliance / comfort
        • Day care procedure
      • OPTIMIZATION
      • NO RADIATION HAZARDS
      • SMALL APPLICATOR
        • Less tissue trauma
        • Better packing
    • 12. MDR BRACHYTHERAPY
      • ADVANTAGES
        • Comparative shorter T/T time
        • One time treatment can be used
        • Patient convenience
        • Radio biologically acceptable nearer to LDR Brachytherapy
      • DISADVANTAGES
        • Late complications increases if correction not done
    • 13. SOURCE LOADING TECHNIQUE
      • PRELOADING SYSTEM
        • Live sources
        • ADVANTAGES
          • Clinical results are best
          • Affordable
          • Long term results with lesser morbidities
        • DISADVANTAGES
          • Radiation hazards
          • Special instruments
          • Difficult application / hasty
          • Geometry not maintained
          • ? Optimization
    • 14. AFTER LOADING TECHNIQUE
      • MANUAL
        • Avoids radiation protection issue of preloading
        • Better applicator placement
        • Verification prior to source placement
        • Min. radiation hazard
        • Advantages of preloading
      • REMOTE CONTROLLED
        • No radiation hazard
        • Accurate placement
        • Geometry maintained
        • Better dose distribution
        • Highly precise
        • Short T/T time
        • Day care procedure
        • Mainly used for HDR
    • 15. INTERSTITIAL BRACHYTHERAPY
      • Sealed Radioactive sources directly implanted into the tumor in a geometric fashion
      • First suggested by Alexander Graham Bell
      • ADVANTAGES
        • Higher local dose in shorter time
        • Rapid dose fall
        • Better tumor control
        • Lesser radiation morbidities
        • Superior cosmetics
        • Functional preservation of organs
    • 16. INTERSTITIAL BRACHYTHERAPY…
      • DISADVANTAGES
        • Radiation hazards in older days
        • Costly
        • Not applicable to inaccessible areas
      • INTENTION OF TREATMENT
        • Always RADICAL
          • As radical brachytherapy alone (smaller lesions)
          • Local boost in combination with EBRT (larger lesion)
          • NEVER USED FOR PALLIATION
    • 17. SELECTION CRITERIA
      • Easily accessible lesions, at least from one side
      • Early stage disease
        • T 1 -T 2 and sometimes early T 3
        • Ideally total size of implant ≤ 5 cm
      • Non DM /HTN
      • No local infection
      • Proliferative and ulcerative lesions preferred
    • 18. CLINICAL APPLICATIONS
      • Head & neck tumors
        • Early stage oropharyngeal cancers
      • Ca breast- Boost /PBI
      • Ca prostate
      • Soft tissue sarcoma
      • Gynecologic malignancies
      • Ca anal canal and rectum
      • Ca lung and pancreas
    • 19. TYPES OF INTERSTITIAL IMPLANTS ACCORDING TO SIZE/LOCATION/PROXIMITY OF TUMOR TO NORMAL STRUCTURES
      • TEMPORARY
        • Radioactive sources removed after desirable dose has been delivered
        • Rigid stainless steel needles/flexible Teflon / nylon guides/plastic tubes
        • Preloaded/After loaded
      • PERMANENT
        • Preloaded – rigid needle eg. Ra 226 ,Cs 137
        • After loaded – Manual/ Remote
        • Advantages
          • Flexibility of implant design
          • Reduction of radiation exposure levels resulting in more accurate placement of needles and guides
    • 20. SYSTEMS OF IMPLANT DOSIMETRY
      • OBJECTIVES OF TREATMENT PLANNING
        • To determine the distribution & type of radiation sources to provide optimum dose distribution
        • To provide complete dose distribution in irradiated volume
      • SYSTEM USED
        • Paterson-Parker (Manchester) system
        • Quimby system (Memorial) system
        • Paris system – Pierquin, Chassagne , Dutreix and Marinello
        • Computer System
    • 21. SYSTEMS OF IMPLANT DOSIMETRY
      • These system designed during times when computers were not available for routine planning
      • Extensive table & elaborate rules of source distribution were devised to facilitate the process of manual treatment planning
      • These systems differ in rule of implantation, definition of dose uniformity & method used in reference dose specification
    • 22. RULES OF INT.IMPLANT SYSTEM PARAMETERS MANCHESTER QUIMBY PARIS COMPUTER Linear strength Variable Constant Constant Constant Source distribution Planar implant:(periphery) Area <25 cm- 2/3 Ra; 25-100 cm- ½ Ra; >100 cm- 1/3 Volume implant::Cylinder:belt-4 parts,core-2,end-1 Sphere:shell-6,core-2 Cube :each side-1,core-2 Uniform Uniform Uniform Line sources parallel planes Uniform Line sources Parallel or cylinderic volumes Spacing line source Constant approx. 1 cm apart from each other or from crossing ends Same as Manchester Constant, Selective Separation 8-15 mm Constant Selective Crossing needles Required to enhance dose at implant ends Same Crossing needles not used;active length 30-40% longer Crossing needles not used;active length 30-40% longer
    • 23. COMPONENTS-CLASSICAL SYSTEM
      • DISTRIBUTION RULES : given a target volume, distribution rules determine how to distribute RA sources & applicators in & around target volume
      • DOSE SPECIFICATION & IMPLANT OPTIMIZATION CRITERIA : Each system has a definition of prescribed dose
      • Above 2 criteria determine dose homogeneity, normal tissue sparing, no. of catheters implanted & margins around target
      • DOSE CALCULATION AIDS : Older systems used tables that give dose delivered per mg Ra-Eq-hr as a function of treatment volume or area
        • Recent Paris system uses computerized treatment planning to relate absorbed dose to source strength & treatment time
    • 24. PRINCIPLE-MANCHESTER SYSTEM FEATURES DOSE & DOSE RATE 6000-8000 R in 6-8 days (1000 R/day; 40 R/hr) UNIT / USE OF RADIUM mg Ra hr – defined as amount of radium to give specified dose in 1 hr DOSE SPECIFICATION CRITERA Effective minimum dose 10% above absolute minimum dose LINEAR ACTIVITY Variable: 0.66 and 0.33 mg RaEq/cm
    • 25. QUIMBY SYSTEM
      • Developed by Edith Quimby et al
      • Dose 5000-6000 R in 3-4 days
      • Equal linear intensity (mg RaEq/cm) needles distributed uniformly (fixed spacing) in each implant, although spacing selected in 1-2 cm range acc. to implant size
      • Quimby tables (Nomogram ) give mg RaEq-hr to deliver stated exposure of 1000 R as function of T.V. or area (5000-6000 R over 3-4 days; 60-70 R/hour)
      • No clear description of rules for distributing Ra needles
      • Crossing recommended; peripheral needles placed on or beyond T.V. boundaries
      • Dose specification criteria inconsistent
      • NOT RECOMMENDED FOR CLINICAL USE
    • 26. PARIS SYSTEM- PRINCIPLES
      • RADIOACTVE SOURCES
      • Rectilinear/parallel -arrangement so that centers are located in the same plane which is perpendicular to the direction of sources- CENTRAL PLANE
      • Equidistant
      • Linear activity-uniform and identical
      • Source geometries
        • Linear- single-plane implants
        • Squares/Equilateral triangles- two plane implants
    • 27. PARIS SYSTEM FEATURES DOSE AND DOSE RATE 6000 -7000 cGy in 3-11 days DOSE PRESCRIPTION POINT Average of the minimum doses in the region defined by the source REFERENCE DOSE & DOSE GRADIENT 85 % of the BASAL DOSE 15 % between the Reference dose and the Basal dose RA SOURCE PLACEMENT Reference isodose volume covers the treated volume
    • 28. PERMANENT IMPLANTS
      • ADVANTAGES
      • DISADVANTAGES
        • Less accessible sites
        • Cont. ultra low dose rate>Max biological effectiveness
        • Better tissue heal
        • Better effect in slow and radio resistant tumors
        • Improved mobility
        • Environmental issue
        • Dosimetric uncertainties > Later part of T/T becomes less effective
        • Source displacement
        • Large tumor > Difficult procedure and geometry
        • Radio biologically less effective for rapidly proliferating tumors
    • 29. COMPUTER SYSTEM
      • Implant system evolved through use of computers
      • Implantation rules: Sources of uniform strength
      • Spaced uniformly (1-1.5 cm), larger spacing for larger implants to cover entire T.V.
      • Active length 30-40% longer than Target length as ends uncrossed
      • T.V.: sufficient safety margins; peripheral sources implanted on outer surface
      • Dose specified by isodose surface that surrounds target
      • Whole planning with help of computers
    • 30. COMPUTER DOSIMETRY
      • Possible to preplan implants & complete isodose distribution corresponding to final source distribution
      • Rapid & fast; helps modify implant
      • Isodose patterns can be magnified & superimposed on implant radiograph
      • Localization of sources:
        • Orthogonal Imaging method
        • Stereo-shift method
        • CT
      • Dose Calculation:
        • No. of milligrams or millicurie in implant
        • Location of each source with respect to dose calculation point
        • Type of isotope being used
        • Filtration of the encapsulation
    • 31. COMPUTER DOSIMTERY
      • Dose Computation:
        • Dose calculation Formalisms’ (AAPM TG 43 algorithm)
          • Use Sievert Integral directly
          • Precalculated dose tables
            • For Radium & other long lived sources: Dose rates in form of isodose curves
            • For Iridium & relatively short lived implants: Computer calculates cumulative dose with decay correction
    • 32. CLINICAL APPLICATIONS
      • Oral Cavity:
      • LIP:
        • Indications: T1-2N0 Lesions
        • T.V.: All visible & palpable tumour with 5-10 mm margin
        • Dose: 50-70Gy in 5-7 days LDR
        • Technique:
          • Rigid afterloading needles maintained in place by Template
          • Classical plastic tubes
        • Spacers to decrease dose to gingiva, teeth & other lip
    • 33. CLINICAL APPLICATIONS…
      • Buccal Mucosa:
        • Indications:
          • Brachytherapy alone indicated for small (<4cm), well-defined lesions in anterior 2/3 rd
          • As boost after EBRT for larger lesions
        • T.V.: GTV + margins
        • Dose: Alone 65-70 Gy
            • Boost 25-30 Gy
        • Technique: Guide Gutter Technique: Lesion < 2cm
        • Plastic tube technique : For other lesions
    • 34. CLINICAL APPLICATIONS…
      • Oral Tongue:
      • Indications: T1 N0, T2 N0 < 3cm lesion
      • T.V.: GTV + 5 mm margin
      • Dose: Alone:60-65 Gy LDR
          • Boost 20-25 Gy after EBRT dose of 45-50 Gy
      • Techniques: Guide-gutter technique
      AP X-ray
    • 35. CLINICAL APPLICATIONS…
      • Floor of Mouth :
        • Indications: T1-2N0 lesions, ≥ 5 mm away from mandible
        • Dose: Techniques same as for Tongue implants
        • Complication: Osteoradionecrosis:5-15%
      • Oropharynx:
        • Indications: Ca BOT , soft palate, tonsillar fossa & vallecula usually as boost after EBRT
          • Lesions < 5 cm (after EBRT)
        • T.V.: GTV + 10 mm margin
        • Dose: Tonsillar fossa-25-30 Gy; BOT 30-35 Gy
        • Technique: Classical Plastic Loop technique
    • 36. CLINICAL APPLICATIONS…
      • Breast
        • Indications: Boost after BCS & EBRT
              • Postoperative interstitial irradiation alone of
              • the primary tumor site after BCS in selected
              • low risk T1 and small T2N0 (PBI)
              • Chest wall recurrences
      Moderator: Prof. S. C. Sharma As sole modality As Boost to EBRT
      • Patient choice: cannot come for 5-6 wks treatment :
          • Distance
          • Lack of time
      Close, positive or unknown margins Elderly, frail, poor health patient EIC Large breasts: unacceptable toxicity Younger patients Deep tumour in large breast Irregularly thick target vol.
    • 37. CLINICAL APPLICATIONS…
      • T.V.: Primary Tumor site + 2-3 cm margin
      • Dose: As Boost: 10-20 Gy LDR
          • AS PBI: 45-50 Gy in 4-5 days LDR (30-70 cGy/hour)
              • 34 Gy/10#, 2# per day HDR
      • Technique:
        • Localization of PTV: Surgical clips (at least 6)
          • USG, CT or MRI localization, Intraop USG
        • During primary surgery
        • Guide needle technique or
        • Plastic tube technique using Template
          • Double plane implant
          • Skin to source distance: Minimum 5 mm
    • 38. CLINICAL APPLICATIONS…
    • 39. CLINICAL APPLICATIONS…
      • Prostate:
      • Indications
        • Brachytherapy as monotherapy:
          • Stage T1-2a & Gleason score 2-6 & PSA ≤ 10 ng/ml
        • As boost after EBRT
          • Stage T2b, T2c or Gleason score 7-10 or PSA > 10 ng/ml
        • For brachytherapy, Prostate size < 50 cc
      • Exclusion criteria:
        • Life expectancy < 5 yrs
        • Large or poorly healed TURP defect
        • Distant Mets or operative risk
      • T.V.: Whole prostate within capsule + 2-3 mm margin
      • Methods: Permanent Implant (I 125 or Pd 103 ) or
      • Temporary Implant (Ir 192 )
    • 40. CLINICAL APPLICATIONS…
      • Technique for Permanent implant
      • Retropubic approach with I 125 seeds- Disappointing results
      • Modern technique: Transperineal Approach
        • TRUS guided
        • Two step approach
          • Volume study of prostate
        • Computer planning
          • Seed positioning
      • Coverage check -USG & Flouroscopy
      • Check Cystoscopy
      • Post-implant image based dosimetry
    • 41. CLINICAL APPLICATIONS
      • Dose:
        • I 125 : 145 Gy as sole RT
            • 100-110 Gy as boost to 40-50 Gy EBRT
        • Pd 103 : 125 Gy as sole RT
            • 90-100 Gy as boost to 40-50 Gy EBRT
      • Temporary Implants with Ir 192 (LDR or HDR):
        • Procedure same as above; lesser no. of plastic catheters required (8-15)
        • Dose:
          • LDR 30-35 Gy seeds left for 3 days(Boost to 45 Gy EBRT)
          • HDR 20-25 Gy, 4-6 Gy/#(Boost to 45 Gy EBRT)
    • 42. CLINICAL APPLICATIONS
      • Soft tissue Sarcomas (using Ir 192 or I 125 )
      • Indications:
        • As sole postop RT:
          • completely resected intermediate or high grade tumours of extremity or superficial trunk with -ve margins
        • As boost to postop EBRT:
          • Intermediate or high grade sarcoma with +/- margins
          • Postop pts with small lesions & +ve/uncertain margins
          • Deep lesions
          • Low grade sarcomas
      • T.V.: GTV + 2-5 cm margin
          • GTV based on preop MRI & clinical findings
      • Dose: LDR (Ir seeds or wires) as sole treatment 45-50 Gy in 4-6 days
          • As boost to 45-50 Gy EBRT: 15-25 Gy in 2-3 days
    • 43. CLINICAL APPLICATIONS…
      • Technique:
        • Usually performed at time of surgery
        • Basic or sealed end temporary implant technique
    • 44.
      • Brain: Permanent or temporary (using I 125 or Ir 192 seeds/wires )
      • Indications:
        • As boost to EBRT or recurrence
        • Anaplastic astrocytoma or GBM, unifocal, well cicumscribed, peripheral lesions & < 5 cm in diameter
      • T.V.: Contrast enhancing area on MRI +/- 5mm margin
      • Dose: LDR 50-60 Gy, 0.4-0.5 Gy/hr
      • Technique: Planning CT/MRI done
      CLINICAL APPLICATIONS…
    • 45. CLINICAL APPLICATIONS…
      • Ca Anorectum
      • Indications: As boost to EBRT/ChemoRT
            • If T.V. doesnot exceeds 1/2 circumference, 5 mm thick, 5 cm long i.e. T1-2 & small T3 lesions
            • T1N0 adenocarcinoma of rectum 3-10 cm above anus
      • T.V.: Visible palpable tumor+5 mm
      • Dose: LDR 15-20 Gy at 0.3-0.6 Gy/hr
      • Technique: Guide needle technique with template
    • 46. CLINICAL APPLICATIONS…
      • Gynecological Tumors ( Ir 192 LDR or HDR)
      • Indications:
        • Ca Cervix
        • Ca Endometrium
          • Postop local recurrence
        • Ca Vagina & Vulva
          • Radical BT in select early lesions (T1-2N0)
          • Boost after EBRT in large lesions (T2-3N1)
      • Technique:
        • Guide-gutter technique
        • Blind plastic tube implant
        • (transperineal technique)
        • Plastic or guide needles
    • 47. CLINICAL APPLICATION – CA CX
          • ABS Recommendations
          • Bulky primary disease
          • Prior hysterectomy-inability to place tandem
          • Post hysterectomy
            • vault recc./cut-through hysterectomy/cervical stump presentation
          • Extesive parametrial involvement
          • Distorted anatomy
            • Narrow vagina & fornices
            • Extensive / Distal vaginal wall involvement
          • Re-irradiation after recurrences
          • Prior course of RT to area of interest
    • 48. CLINICAL APPLICATIONS…
        • PERINEAL IMPLANTS
      Martinez Universal Perineal Interstitial Template (MUPIT ) Syed-Neblett template
    • 49. CLINICAL APPLICATIONS…
      • Dose:
        • Radical BT:
          • LDR: 55-60 Gy @ 50-90 cGy/hr
          • HDR: 3.5 Gy/#@ 2#/day/12-16#
        • Boost
          • LDR: 15-25 Gy , 50-90 cGy/hr
          • HDR: as above, no. of # depend upon EBRT doses
    • 50. CLINICAL APPLICATIONS…
      • Other sites:
        • Lung: Permanent perioperative BT, I 125 seeds, Au 198 Grains
            • Persistent or recurrent ds after EBRT or residual ds after surgery
        • Pancreas: Permanent perioperative BT, I 125 seeds
            • Locally advanced unresectable ds
        • Penis & Urethra:
    • 51. INTRACAVITARY APPLICATION
      • Radioactive sources are placed in a existing cavity usually inside a predefined applicator with special geometry
      • Uses:
        • Cervix
        • Endometrium
        • Vagina
        • Maxilla
        • Nasopharynx
    • 52. PARIS SYSTEM
      • Single application of radium
      • Two cork colpostats (cylinder) and an intrauterine tube
      • Delivers a dose of 7000- 8000 mg-hrs of radium over a period of five days(45R/hr) (5500mg/hr
      • Equal amount of radium used in the uterus and the vagina
      • Intrauterine sources
        • 3 radioactive sources, with source strengths in the ratio of 1:1:0.5
      • colpostats
        • sources with the same strength as the topmost uterine source
    • 53. STOCKHOLM SYSTEM
      • Fractionated course of radiation delivered over a period of one month.
      • Usually 2-3 applications, each for a period of 20- 30 hours (repeated 3weekly)
      • Intravaginal boxes -lead or gold intrauterine tube -flexible rubber
      • Unequal loading
        • 30 - 90 mg of radium in uterus
        • 60 - 80 mg in vagina
      • Total prescribed dose -6500-7100 mg Ra
        • 4500 mg Ra contributed by the vaginal box (dose rate-110R/hr or 2500mg/hr/#)
    • 54. DRAWBACKS OF PARIS AND STOCKHOLM SYSTEMS
      • Long treatment time
      • Discomfort to the patient
      • No dose prescription
    • 55. MANCHESTER SYSTEM
      • To define the treatment in terms of dose to a point. Criteria of the point:
        • Anatomically comparable
        • Position
          • where the dosage is not highly sensitive to small alteration in applicator position
          • Allows correlation of the dose levels with the clinical effects
      • To design a set of applicators and their loading which would give the same dose rate irrespective of the combination of applicators used
      • To formulate a set of rules regarding the activity, relationship and positioning of the radium sources in the uterine tumors and the vaginal ovoids, for the desired dose rate
    • 56. POINT A
      • PARACERVICAL TRIANGLE where initial lesion of radiation necrosis occurs
      • Area in the medial edge of broad ligament where the uterine vessel cross over the ureter
      • The point A -fixed point 2cm lateral to the center of uterine canal and 2 cm from the mucosa of the lateral fornix
      • POINT B
      • Rate of dose fall-off laterally
      • Imp. Calculating total dose-Combined with EBRT
      • Proximity to important OBTURATOR LNs
      • Same level as point A but 5 cm from midline
      • Dose ~20-25 % of the dose at point A
    • 57.  
    • 58. LOADING OF APPLICATORS
      • In order that point A receives same dosage rate no matter which ovoid combination is used ,it is necessary to have different radium loading for each applicator size
      • Dose rate 57.5 R/hr to point A
      • Not more than 1/3 dose to point A must be delivered from vaginal radium
      • APPLICATORS
    • 59. LOADING PATTERN TUBE TYPE LENGTH TUBES RADIUM (mg) UNITS (FUNDUS to CX) LOADING TUBES (mg) LARGE 6 3 35 6-4-4 15-10-10 MEDIUM 4 2 25 6-4 15-10 SMALL 2 1 20 8 20 VAGINAL OVOIDS TUBES RADIUM (mg) UNITS LOADING TUBES(mg) LARGE 3 22.5 9 10-10-5 or 20/25 MEDIUM 2 20 8 20 SMALL 1 17.5 7 10-5-5 or 20/15
    • 60. GUIDELINES
      • Largest possible ovoid
        • Lesser dose to mucosa
      • Longest possible tandem (not > 6 cm)
        • Better lateral throwoff
        • Smaller dose to mucosa
      • Dose to point A- 8000R
      • Dose to uterus wall -30,000R
      • Dose to vaginal mucosa-20,000R
      • Dose to recto-vaginal septum- 6750 R
      • Dose limitation
        • BLADDER <80 Gy
        • RECTUM <75 Gy
    • 61. INTRACAVITARY APPLICATORS
      • MANCHESTER
      • PGI
    • 62. IDEAL APPLICATION
      • Tandem
        • 1/3 of the way between S1 –S2 and the symphysis pubis
        • Midway between the bladder and S1 -S2
        • Bisect the ovoids
      • Marker seeds should be placed in the cervix
      • Ovoids
        • against the cervix (marker seeds)
        • Largest
        • Separated by 0.5-1.0 mm
        • Axis of the tandem-central
      • Bladder and rectum - should be packed away from the implant
    • 63. ICRU REPORT NO.38
      • DOSIMETRIC INFORMATION FOR REPORTING
      • Complete description
        • Technique
        • Time-dose pattern
      • Treatment prescription
      • Total Reference Air Kerma
      • Dose description
        • Prescription points/surface
        • Reference dose in central plane
        • Mean central /peripheral dose
      • Volumes: Treated/ point A/ reference volume
      • Dose to Organs at Risk : bladder, rectum
    • 64.
      • REFERENCE VOLUME
        • Dimensions of the volume included in the corresponding isodose
        • The recommended dose 60 Gy
      • TREATED VOLUME
        • Pear and Banana shape
        • Received the dose appropriate to achieve the purpose of the treatment, e.g., tumor eradication or palliation, within the limits of acceptable complications
      • IRRADIATED VOLUME
        • Volumes surrounding the Treated Volume
        • Encompassed by a lower isodose to be specified, e.g., 90 – 50% of the dose defining the Treated Volume
        • Reporting irradiated volumes may be useful for interpretation of side effects outside
    • 65. CERVICAL BRACHYTHERAPY
    • 66. ABS.DOSE AT REFERENCE POINTS
      • BLADDER POINT
      • RECTAL POINT
      • LYMPHATIC TRAPEZOID OF FLETCHER
        • LOW PA, LOW COMM.ILIAC LN & MID EXT ILIAC LNs
      • PELVIC WALL POINTS
        • DISTAL PART OF PARAMETRIUM & OBTURATOR LNs
    • 67. DOSE SCHEDULE
      • LDR (<200cgy/hr)
        • 35-40 Gy at point A
      • MDR (200-1200cgy/hr)
        • 35 Gy LDR EQUIVALENT at point A
      • HDR(>1200cgy/hr)
        • 9 Gy in 2 #
        • 6.8Gy in 3# at point A
    • 68. EXTERNAL RT WITH BRACHYTHERAPY
      • Brachytherapy can follow external irradiation
        • SIMULTANEOUS
          • Stage I - II with very minimal parametriun involvement
          • HDR -5 sessions (9gy /#/ 5, 1week apart)
          • 40 Gy by XRT simultaneously
        • SANDWICH
          • Stage I-II
          • MDR 40 Gy LDR eq.—› XRT 40 Gy —› MDR 35 Gy LDR eq.
      • In both above cases a MIDLINE SHIELD is used
    • 69. POST OP/ VAULT BRACHYTHERAPY
      • Vault RT
        • No residual disease
          • 8500 cGy at 5mm from the surface of the vault
          • 2 sessions 1 week apart
        • Residual disease
          • CTV of 2 cm given to gross tumor and the prescription of 8500cgy encompassing the whole CTV is made
          • 2 sessions 1 week apart
      • Mostly after XRT
    • 70. POST OP BRACHYTHERAPY
      • CONTRAINDICATIONS
        • Vaginal wall involvement ( middle- lower 13)
        • Heavy parametrium infiltration
        • VVF or VRF
        • Inadequate space
        • Medical contraindications
        • Metastatic disease
      • Supplementary radiation 2000 cGy 10# 2 weeks
    • 71. SURFACE MOULDS
      • Radiation is delivered by arranging RA sources over the surface of tumor
      • Types
        • Planar
          • Circular
          • Square
          • Rectangular
        • Line source
        • Cylinder
    • 72. INDICATIONS
      • Superficial /Accessible tumors
      • Skin ca
      • Post mastectomy recurrence
      • Oral tumor
        • hard palate ,alveolus
      • Penile carcinoma
    • 73. CIRCULAR MOULDS
      • Amount of radium used is obtained from the table for a particular treating distance
      • Circular arrangement is the best
      • Space between the needles (end) should not be more than H
    • 74. SQUARE MOULDS
      • An arrangement is considered to be linear if the distance between the active end of the sources does not exceed the height
      • Length of the side of the square is less than twice the height
        • No further radium is placed in the center
    • 75. RECTANGULAR MOULDS
      • The dividing lines or bars are placed parallel to the longer side
      • Elongation correction factor: Increase the reading in milligrams hour by a given factor
        • This factor is proportional to the ratio of the sides of the rectangle
          • 1.5:1 = 2.5%
          • 2:1 = 5%
          • 3:1 = 9%
          • 4:1 = 12%
    • 76. CIRCULAR MOULDS
      • CURVED SURFACES
      • COAXIAL RINGS
      • Irregular area
      • Curved surfaces: convex, concave
        • The smaller area is used for calculation of radium dose and implant rules
      • Cylinder mould: Amount of radium is 30D 2
      • DISTRIBUION RULES
        • In case of coaxial rings radium is placed at a distance equal to 2H
    • 77. INTRALUMINAL BRACHYTHERAPY
      • Radioactive source is passed through a tube and passed into a hollow lumen
      • Sites
        • Esophagus
        • Bronchus : Bronchogenic carcinoma
          • Definitive : T 1 -T 2 tumors
          • Palliative
            • Dyspnea
            • Cough
            • Atelectasis
        • Biliary tract
    • 78. RADIOBIOLOGY
      • Biological effects depend on
        • Dose prescribed
        • Treated volume
        • Dose rate
        • Fractionation
        • Treatment duration
      • Heterogeneous dose distribution
      • Higher average dose
      • Short treatment
    • 79. RADIOBIOLOGY – 4 Rs
      • Repair
      • Reassortment / redistribution
      • Repopulation
      • Reoxygenation
    • 80. RADIOBIOLOGY- LDR
      • Repair of Sublethal damage
      • Most significant- 1 Gy/min and 0.3 Gy /h
      • DNA repair
        • Dynamic process
        • Special kinetics
      • Simple exponential kinetics
      • Reassortment - slow and imp. <1 Gy/min
      • Repopulation-slowest and significant
      • Reoxygenation - relative slow process may be a disadvantage
    • 81. LDR AND HDR
      • LDR vs HDR
      • EFFECTS OF HDR
    • 82. RADIOACTIVE SOURCES
      • Naturally occurring
      • Artificial
      • Induced by neutron bombardment
      • Induced by bombardment of protons
      • Fission product
      • CHARACTERISTICS
        • HALF LIFE
        • GAMMA ENERGY
        • BETA ENERGY
        • HALF VALUE LAYER
        • EXPOSURE RATE CONSTANT
        • BETA FILTRATION
        • DECAY SCHEME
    • 83. IDEAL RADIONUCLIDE
      • Photon energy :low to medium- 0.03 to 0.5 MeV
        • Monoenergetic beam preferred
      • Moderate Gamma ray constant
      • Long half life
      • High specific activity
      • Isotropic
      • No gaseous disintegration/daughter product
      • Nuclei should not disperse if source damaged
      • Low beta energy
      • Low or no self attenuation
      • Insoluble and nontoxic
      • Flexible
      • Easily available and cost effective
      • Withstand sterilization process
      • Disposable without radiation hazards to environment
    • 84. RADIUM 226
      • Sixth member of the radio active series which starts with uranium and ends with lead
      • Half life 1620 years
      • Gamma energy 0.83 MeV
      • Half value 12mm Pb
      • Exposure rate constant 8.25 Rcm 2 /mCi-h
      • Filtration 0.5 – 1 mm Pt
    • 85. RADIUM SUBSTITUTES NAME ORIGIN T 1/2 γ ENERGY-MeV β ENERGY β FILTRATION HVL (Pb -mm) ERC SPECI. ACTI. DECAY PRODUCT Rn 222 NATURAL 3.83 days 0.83 Stainless steel 12 10.27 Pb 206 Cs 137 FISSION 30.17 yrs 0.662 0.512 1.17 - do - 6.5 3.26 87 Ba 137 Co 60 NEUTRON ACTIVAT. 5.26 yrs 1.17, 1.33 0.38 - do- 11 13.07 1020 Ni 60 Ir 192 - do - 73.8 yrs 0.136- 1.06 0.079-0.068 Platinum 4 4.69 7760 Pt 192 Tn 182 - do - 115 yrs 0.67 - Platinum 12 6.87 - - Au 198 - do - 2.7 days 1.088- 0.412 0.96 St. steel 3.3 2.376 - Hg 198 I 125 - do - 59.4 days 0.274, 0.314 No Titanium 0.01 10th 1.403 - Te 125 Pd 103 - do - 16.97 days 0.21 No Platinum 0.03 6.87 - Ru 103
    • 86. Thank You