clinical applications of ldr and hdr brachytherapy
DESCRIPTION
clinical applications of LDR-HDR brachytherayTRANSCRIPT
DR. SUGASHWARAN. J,MODERATOR:PROF.DR.G. V. GIRI,DEPT. OF RADIATION ONCOLOGY,KMIO, BANGALORE.
CLINICAL APPLICATIONS OF LDR-HDR BRACHYTHERAPY
BRACHYTHERAPY
Type of radiation treatment Consists of placing sealed
radioactive sources very close to or in contact with the target tissue.
CLINICAL ADVANTAGES
High biological efficacy Rapid dose fall-off High tolerance Tolerable acute intense reaction Decreased risk of tumor population High control rate Minimal radiation morbidity Day care procedure
LIMITATIONS & DISADVANTAGES Difficult for inaccessible regions Limited for small tumors (T1_T2) 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
SELECTION CRITERIA Easily accessible lesions Early stage diseases (Ideal implant ≤ 5
cm) Well localized tumor to organ of origin No nodal or distant metastases (radical
intent) No local infections or inflammation Favorable histology- mod. diff. i.e. SCC Well controlled DM / HTN Proliferative/exophtic lesions preferred
(better outcome)
INDICATIONS
SOLE MODALITY Skin
malignancies- BCC, SCC
Head & neck cancers
Ca cx Ca prostate
BOOST( AFTER EXT.RT±CCT) Head & neck
cancers Ca Breast Esophagus Anal canal
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
CLASSIFICATION
SURGICAL APPROACH / POSITIONING SOURCE IN TUMOR
INTERSTITIAL INTRACAVITARY INTRALUMINAL ENDOVASCULAR
SOURCE IN CONTACT BUT SUPERFICIAL SURFACE
BRACHYTHERAPY/ MOULD
DURATION OF IRRADIATION TEMPORARY-
Cs137,Ir192
PERMANENT-I125,Au198
Pd 103 .Cs 131
DOSE RATE(ICRU 38)
LOW DOSE RATE (LDR) 0.4-2 Gy/hr (clinical practice range 0.4 to
1 Gy per hour) 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
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 TREATMENT TIME Geometry well maintained Better patient compliance /
comfort Day care procedure
DOSE OPTIMIZATION NO RADIATION HAZARDS SMALL APPLICATOR
Less tissue trauma Better packing
AFTER LOADING TECHNIQUE
MANUAL Avoids radiation
protection issue of preloading
Better applicator placement
Verification prior to source placement
More radiation hazard
Advantages of preloading
REMOTE CONTROLLED No radiation hazard Accurate placement Geometry maintained Better dose
distribution Highly precise Short Treatment
time Day care procedure Mainly used for HDR
RADIOBIOLOGY
Biological effects depend on Prescribed dose Treated volume Dose rate Fractionation Treatment duration
RADIOBIOLOGY – 4 Rs
Repair Reassortment / redistribution Repopulation Reoxygenation
INTERSTITIAL BRACHYTHERAPY Sealed Radioactive sources directly
implanted into the tumor in a geometric fashion
ADVANTAGES Higher local dose in shorter time Rapid dose fall Better tumor control Lesser radiation morbidities Superior cosmetics Functional preservation of organs
INTERSTITIAL BRACHYTHERAPY… DISADVANTAGES
Invasive procedure Costly
INTENTION OF TREATMENT RADICAL INTENTION
As radical brachytherapy alone (smaller lesions)
Local boost in combination with EBRT (larger lesion)
SELECTION CRITERIA
Easily accessible lesions, at least from one side
Early stage disease T 1-T2 and sometimes early T3 Ideally total size of implant ≤ 5 cm
Well controlled DM /HTN No local infection
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
TYPES OF INTERSTITIAL IMPLANTSACCORDING 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. Ra226 ,Cs137 After loaded –
Manual/ Remote Advantages
Flexibility of implant design
Reduction of radiation exposure levels resulting in more accurate placement of needles and guides
PERMANENT IMPLANTS
ADVANTAGES DISADVANTAGES
Less accessible sites 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 Treatment becomes less effective
Source displacement Large tumor /Difficult
procedure and geometry
Radio biologically less effective for rapidly proliferating tumors
CLINICAL APPLICATIONSOral Cavity: LIP:
Indications: T1-2N0 Lesions (monotherapy- 0.5to5 cm or boost therapy->5 cm)
T.V.: All visible & palpable tumour with 5-10 mm margin
Dose: 50-70Gy in 5-7 days LDR Technique:
Rigid after loading needles maintained in place by Template
Classical plastic tubes Spacers to decrease dose to gingiva, teeth &
other lip
CLINICAL APPLICATIONS…Buccal Mucosa:
Indications: Brachytherapy alone indicated for small
(<4cm), well-defined lesions in anterior 2/3rd
As boost after EBRT for larger lesions T.V.: GTV +0.5 to 1 cm margins Dose: Alone 65-70 Gy
Boost 25-30 Gy Technique: Guide Gutter Technique: Lesion <
2cm Plastic tube technique: For other lesions
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
CLINICAL APPLICATIONS…Floor of Mouth:
Indications: T1-2N0 lesions, ≥ 5 mm away from mandible
Dose: monotherapy-65Gy;boost-20 to 30 Gy Complication: bone necrosis is most
common, up to 30%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
CLINICAL APPLICATIONS… Nasopharynx: Ind- T1 AND T2 lesions
Dose: LDR -as a sole treatment 60Gy; as a boost 12 to 20 Gy.
HDR- 18 Gy in 6 fr
Opthalmic brachytherapy(I-125,Ru-106,Sr90)
Ind- malignant tumors of the conjuctiva, pterygium,wet macular degeneration,neovascularization
Sr 90 dose rate-100Gy/hr,, I-125 dose rate 0.5 to 1 Gy/hr
Pterygium – Sr 90 dose varying from 20 to 60 Gy in 1 to 6 fr.
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
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 with EBRT
Younger patients
Deep tumour in large breast
Irregularly thick target vol.
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/10fr, 2fr per day HDR
Technique: Localization of PTV: Surgical clips (at least
6) USG, CT or MRI localization, Intra op USG
During primary surgery Guide needle technique or Plastic tube technique using Template
Double plane implant Skin to source distance: Minimum 5 mm
MAMMOSITE
Used for Accelerated Partial Breast Irradiation(APBI)
Fluid filled balloon placed during surgeryPrescriptionReference Point at 1 cm340cGy per fraction2 fractions per day6 hour separation10 fractions total Weekend break is allowed
Ideal patients for APBI(ASTRO)
Tumor Size < 2 cm Absence of nodal involvement(N0) Absence of Metastatic Status(M0) Age > 60 yr Negative margins Invasive ductal histology in the
absence of DCIS Estrogen receptor positive
HDR Brachytherapy with Savi The Savi applicator is a new single
insertion multicatheter device used for partial breast radiation.
It has a single central catheter and multiple peripheral catheters.
This allows the radiation dose to be tailored to the shape of the lumpectomy cavity.
Contura- multi lumen baloon Consists of a central lumen and 4 outer
lumen offering a total of 40 dwell positions Encased in a polyurethane balloon which
maintains symmetry and reduces potential for balloon ruputre.
NEW ELLIPTICAL BALOON(2004) Provides excellent conformance
Ellipsoidal implant parellel to the chest wall provides appropriate symmentry
AXXENT:NEWER DEVICE Uses a miniaturized x-ray source to deliver low energy
x-rays within a needle or catheter. Use of this device for APBI No need for heavy room shielding Stay in room with patient during treatment No radioactive materials license needed No handling, storing, security concerns One source per patient Must calibrate source before each treatment
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 /Gleason score 7-10 /PSA > 10 ng/ml
Patient factors : Life expectancy > 5 yrs IPSS<15 Prostate volume<60cm22
No defect if previous TURP Minimal pubic arch interfence
T.V.: Whole prostate within capsule + 2-3 mm margin
Methods: Permanent Implant (I125 or Pd103) or
Temporary Implant (Ir192)
CLINICAL APPLICATIONS… Technique for Permanent
implant Retropubic approach with I125 seeds-
Disappointing results Modern technique: Transperineal Approach
TRUS guided Two step approach
Volume study of prostate pubic arch interfence assessment
Computer planning Coverage check -USG & Flouroscopy Bladder irrigation /Cystoscopy can be performed Post-implant image based dosimetry
CLINICAL APPLICATIONS Dose:
I125: 145 Gy as sole RT;100-110 Gy as boost to 40-50 Gy EBRT
Pd103: 125 Gy as sole RT;90-100 Gy as boost to 40-50 Gy EBRT
Cs 131 :115 GY as sole rt;85-95 Gy as boost to 40-50 Gy EBRT
Temporary Implants with Ir192 (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)
CLINICAL APPLICATIONSSoft tissue Sarcomas (using Ir192 or I125) 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 daysHDR: as sole treatment 40 t0 50 Gy in 12 to 15 fr/
as boost to 45-50 Gy EBRT:18-25 Gy in 4-8 fr
CLINICAL APPLICATIONS… Technique:
Usually performed at time of surgery Basic or sealed end temporary implant
technique To delay the start of brachytherapy for
about 4 to 7 days after surgery limit the allowable skin dose the 40 Gy
isodoseline to <25cm2 and the 25 Gy isodose line <100 cm2
CLINICAL APPLICATIONS…Brain: Permanent or temporary (using I125 or
Ir192 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
Gliasite
Used to treat brain tumors
Balloon filled with I-125 containing solution Example: used to treat glioblastoma
multiformae to 50 Gy followed by EBRT boost
CLINICAL APPLICATIONS…Ca Anorectum
Indications: As boost to EBRT/ChemoRT
If T.V. does not 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 plastic perineal template
CLINICAL APPLICATIONS…Gynecological Tumors (Ir192 LDR or HDR) Indications:
Ca Cervix Ca Endometrium
Postop local recurrence Ca Vagina & Vulva
Radical BT in 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
CLINICAL APPLICATION – CA CX ABS Recommendations
Bulky primary disease Prior hysterectomy-inability to place tandem
Post hysterectomy vault rec/cervical stump presentation
Extesive parametrial involvement Distorted anatomy Narrow vagina & fornices Extensive / Distal vaginal wall involvement
Re-irradiation after recurrences
CLINICAL APPLICATIONS… PERINEAL IMPLANTS
Martinez Universal Perineal
Interstitial Template (MUPIT)
Syed-Neblett template
CLINICAL APPLICATIONS…
Ca Lung: Permanent perioperative BT, I125 seeds Persistent or recurrent ds after EBRT or residual
ds after surgery
Ca Pancreas: Permanent perioperative BT, I125 seeds Locally advanced unresectable ds
Ca Penis: scc predominant histology,
Indications – T1,T2 and T3(<4cm)that do not involve the shaft of penis.
Based on paris system using templates(12 &18mm)
Dose ;60 Gy at a dose rate of 0.5 to0.65Gy/hr Ca urethra: as sole treatment is 60 to 70 Gy in 3 to 5 days;
as a boost 20 to 25 Gy.
INTRACAVITARY APPLICATION Radioactive sources are placed in a
existing cavity usually inside a predefined applicator with special geometry
Uses: Cervix Endometrium Vagina Maxilla Nasopharynx
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 fr 6.8Gy in 3 fr at point A
EXTERNAL RT WITH BRACHYTHERAPY Brachytherapy can follow external
irradiation SIMULTANEOUS
Stage I - II with very minimal parametriun involvement
HDR -5 sessions (9gy /fr, 1week apart) 40 Gy by EBRT simultaneously
SANDWICH Stage I-II 40 Gy LDR eq.—› EBRT 40 Gy
In both above cases a MIDLINE SHIELD is used
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 EBRT
POST OP BRACHYTHERAPY CONTRAINDICATIONS
Vaginal wall involvement ( middle- lower 1\3)
Heavy parametrium infiltration VVF or VRF Inadequate space Medical contraindications Metastatic disease
Supplementary radiation 2000 cGy \10fr
SURFACE MOULDS Radiation is delivered by
arranging RA sources over the surface of tumor
Types Planar
Circular Square Rectangular
Line source Cylinder
INDICATIONS Superficial /Accessible tumors keloid : Sr90 , 20 gy in 4 fr after
surgery. Skin ca – HAM applicator, Freiburg flab
are surface template applicators, dose – 35 to 50 Gy in 5 to 10 fr.
Post mastectomy recurrence – LDR- 65 Gy in 2 to 3 fr,monthly intervals.
Oral tumor hard palate ,alveolus,oral cavity,lip as a sole modality 60 GY,as boost to 45 to
50 GY- 15 TO 30 Gy. Penile carcinoma
INTRALUMINAL BRACHYTHERAPY Radioactive source is passed through a
tube and passed into a hollow lumen Sites
Esophagus : TV-tumor+distal and proximal margin of 2 to 3 cm
Dose: palliative-16 GY IN 2 FR or 18 GY IN 3 FR.
as boost EBRT 50 Gy-HDR 10 Gy in 2 fr at 1 cm from surface.
ILBT.. Bronchus : Bronchogenic carcinoma
Definitive : T1-T2tumors
HDR- sole treatment-5Gy in 5 fr or 7.5 Gy in 2 fr prescribed to 1cm.
as boost to EBRT treatment(45 TO 60 Gy)- three 5 Gy fr or two 7.5 GY fr
Palliative : Dyspnea,hemoptysis,post obstructive
pneumonitis Poor lung function Previous EBRT Dose : 7.5Gy/fr in3 weekly fr, 10Gy/fr in 2 fr,
6Gy/fr in 4 fr prescribed at 1 cm. Boost treatment- 30 Gy in 10 to 12 fr
Biliary tract Ind – unresectable tumors Technique – endoscopic retrograde
technique BT delivered throug a transhepatic
cholangiogram TV- tumor +1 to 2 cm proximal and
distal margin Monotherapy- palliative dose 30 gy in 6
fr As boost(45 Gy EBRT) – 15 TO 20 Gy in
3 to 4 fr.
Intra vascular brachytherapy Coronary artery disease
caused by occlusion of cardiac vessels
IVB used to prevent restenosis after angioplasty Radiation delivered either with temporary implant or
radioactive stent
Intra operative Radiation brachytherapy
Attractive for deep tumors because the skin dose was limiting prior to the invention of megavoltage accelerators.
Applications include: retroperitoneal
sarcoma, pancreatic cancer, rectal cancer, pediatric tumors,malignant thoracic tumors.
dose of 10 to 20 Gy in single fr over 10 to 30 minutes.
Image guided brachytherapy
Image-guided brachytherapy may provide better dose distribution to the target tumor and reduced dose volumes to surrounding healthy tissues when compared with image-guided IMRT and IMPT.
The use of imaging techniques, such as ultrasound,CT and MRI for treatment planning, has led to improved visualization of the tumor and surrounding organs.
IGBT… Applicators used for IGBRT should be
such that the applicator does not produce an artifact on the cross sectional imaging technique being used. For this purpose special CT/MRI Compatible applicators should be used. The applicators are usually made up of a titanium alloy Now a days carbon fibre based brachytherapy applicators are also available.
MR is an ideal image guidance modality for image guided brachytherapy. Outstanding visualization of pelvic anatomy.
Adaptive Brachytherapy Adaptive Brachytherapy can be
defined as temporally changing the treatment plan delivered to a patient based on observed anatomic changes caused by tumor shrinkage, weight loss, or internal motion.
Plans are altered throughout the treatment course for every course of treatment depending on tumor volume.
Patient setup and organ motion obtained from imaging during treatment to alter the treatment plan.
ROBOTIC BRACHYTHERAPY
Improve accuracy of needle placement and seed delivery
Improve consistency of seed implant Improve avoidance of critical
structures Reduce radiation exposure MAINLY USED FOR CA PROSTATE Seed placement error is at sub
millimeter level.
Intensity modulated brachytherapy This modulation is specific for the patient and allows for
high intensity radiation treatment of tumor tissue with limited destructive effects on surrounding normal tissue.
Intensity modulated sources based on Monte Carlo simulations
a “modified TG43” (mTG43) dose calculation algorithm developed specifically for IMBT dosimetry. the anisotropic function of a IMBT source, is a function of both the position of measurement and the intensity distribution of the source
an inverse IMBT treatment planning method based on Dose Volume Histogram (DVH) or Dose Surface Histogram (DSH) constraints and simulated annealing optimization algorithm.