Image-guided Brachytherapy; CMUH expereinces

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Image-guided Brachytherapy CMUH expereinces
Ekkasit Tharavichitkul, MD The division of
therapeutic radiology and oncology, Faculty of
Medicine, Chiang Mai University, Chiang Mai,
Thailand
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Development of IGBT

• Since the 1938 dosage system description by Tod
  and Meredith, physicians have recorded the dose
  to Points A and B, as well as to the bladder and
  rectal points, as recommended by the
  International Commission on Radiation Units
  (ICRU) 38.
• Applicator location as identiy on two-dimensional
  X-rays
• Fewer complications and higher local control
  rates

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• Nevertheless,
• Two-dimensional imaging does not delineate the
  precise anatomic boundaries for structures
• Physician must rely on contrast placed in the
  vagina, bladder, and/or rectum or on gold seeds
  implanted into the cervix to localize these organs

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Standard
Dose point A Best standard
Early disease 75Gy 90-95
Advanced disease IIB lt 5 cm IIB/IIIB gt 5 cm 80-85Gy 85 Gy 70-85 50-65
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Three-dimensional (3D) imaging

• Ultrasound
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET) scans
• The location of the uterus, cervix, and vagina,
  or the organs at risk (OAR), including the
  sigmoid, rectum, bladder, and small bowel.

Viswanathan, 2009
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• Since the 1990s,
• Implementation of CT simulation for EBT planning
  in radiation oncology departments has enabled
  physicians to contour and perform dose volume
  histogram (DVH) analysis of the OAR.
• In 2004, The American Brachytherapy Society
  (ABS) published guidelines for image-guided
  gynecologic brachytherapy.

Nag, 2004
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• In 2005, the Groupe Europe en CurietherapyEurope
  an Society of Therapeutic Radiation Oncology
  (GEC-ESTRO) has advocated the implementation of
  MR evaluation in cervical cancer brachytherapy
  because of the superiority of MR imaging in
  identifying the cervix and residual tumor

Haie-meder, 2005 Poetter, 2006
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• At a consensus conference in July 2005, the ABS
  and GEC-ESTRO leadership in gynecologic
  brachytherapy agreed to adopt the GEC-ESTRO
  guidelines and to advocate 3D imagebased
  planning for cervical cancer.

Viswanathan, 2009
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GEC-ESTRO recommendations

• 2 Clinical Target Volumes
• A first target related to the extent of GTV at
  diagnosis with an intermediate dose prescribed
  to this target (60 Gy)-Intermediate risk CTV
• A second target related to the extent of GTV at
  time of BT taking into account tumor extent at
  diagnosis. with a high dose prescribed to this
  target (80-90 Gy) -High risk CTV

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/
Haie-Meder, GEC-ESTRO recommendations,2005
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HR CTV

• Derived from point A use
• GTV at the time of BT
• CTV defined for brachytherapy if major response
  limited to cervix and adjacent structures with
  presumed residual disease (30-60 cc)
• Intent 80 to 90 Gy total dose to CTV in
  definitive radiotherapy in advanced disease
• Dose comparable with dose to point A

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High risk CTV

• GTV at time of brachytherapy
• Includes
• Whole cervix
• Presumed tumor extension
• Clinical assessment
• Residual grey zones on MRI
• NO SAFETY MARGINS
• DOSE HIGH ENOUGH TO STERILIZE MACROSCOPIC TUMOUR

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IR CTV
ICRU 38 recommendations GTV at diagnosis ?
CTV at time of brachytherapy CTV including
safety margins with regard to dimensions of GTV
at diagnosis Intent 60 Gy total dose to CTV
in definitive radiotherapy in advanced disease
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HR-CTV IR-CTV
Haie-Meder, GEC-ESTRO recommendations,2005
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Study of MRI-based BT
Studies N Dose EBRT HDR/LDR results
Poetter et al (2007) 130 45 Gy 28 Gy Median follow up 51 months PFS 85 OS 58 G3-4 GI/GU 4
Dimopolous et al (2009) 141 45-50 Gy 28 Gy-HDR D90 for HR-CTV 87 Gy LR incidence 4 vs. 20 (D90 lt 87 Gy)
Kim et al (2009) 51 Total EBRT HDR 85 Gy (IPSA-HDR) At 24.3 months 2/4 Grade 3 acute/late toxicities 48/52 Grade 1-2 GI/GU 2 pts developed recurrence OS 86 (2-yr)
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Study of CT-based BT
Studies N Dose EBRT(Gy) HDR/LDR(Gy) results
Tan et al. (2009) 28 46 21 , HDR 3yr CSS 81 24 pts achieve D90 gt 74 Gy 17 pts no adjustment 9 pts adjustment
Wang et al. (2009) 10 30, HDR Mean CTV shrinkage from 77cm3 in 1st fraction to 65.5 cm3 in 5th fraction CTV volumes directly correlate with point A Bladder ICRU point correlate to 3D-volume Rectum ICRU point did not correlate to 3D plan
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Benefit of IGBT

• Identifications of
• Target organ (HR-CTV, IR-CTV)
• Organs at risk (OARs)
• Allowance of optimization of Targets and OARs
• In accidental conditions uterine perforation
• In special conditions ISBT, combined ICIS

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CT-based brachytherapy
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Our CMUH in CT-based BT in cervical cancer

• From July 2008 to December 2009, CT-based
  planning will be used
• Four field box technique
• 2 Gy per fraction, 5 fractions per week
• To 50 Gy with central shielding at 46 Gy (one
  patient 30 Gy (stage IB))
• Parametrial boost to 56 Gy in advanced case
• All patients received cisplatin or carboplatin as
  concurrent chemoradiation

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• HDR
• Standard tandem-ovoid applicator or CT/MR
  applicator were used
• CT planning with 5 mm slice thickness
• High-risk CTV(HR_CTV), bladder, rectum and
  sigmoid were contoured according to GEC-ESTRO
  recommendations
• Prescription dose 4 x 6.5 Gy
• D90 of HR-CTV
• D2cc bladder, rectum and sigmoid colon

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CT-guided Brachytherapy in cervical cancer

• During July 2008 now
• 17 pts of IB-IIIB cervical cancer was included in
  our study
• Median age 50 (36-60) years
• 15 pts was SCCA, 1 pts was adenocarcinoma , 1
  with Small cell carcinoma

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Patient I
Pre optimized plan
Post optimized plan
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Patient II
Pre optimized plan
Post optimized plan
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Results

• At median follow-up 11.7 months
• No local recurrence were found
• One patient developed supraclavicular metastasis.
  
• Biopsy showed Small cell carcinoma
• Now she received chemotherapy

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Dosimetry
Parameters EQD2 standard plan EQD2 optimized plan
D90 HR-CTV 90.2/-9.7 Gy 87.6/-9.2Gy
D2cc bladder 118.1/-20 Gy 92.14/-6.5 Gy
D2cc rectum 73.7/-8.6 Gy 72.04/-5.6 Gy
D2cc sigmoid 76.2/-11.4 Gy 67.8/-9.1 Gy
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Acute toxicities
SE/Grade Grade1-2 Grade 3-4
skin 12 0
GI 10 0
GU 8 0
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MRI-guided brachytherapy
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MRI guided Brachytherapy

• Two patients
• Stage IIB 1 patient
• Stage IIIB 1 patient
• EBRT with CT-planning
• 1.8 Gy per fraction, 5 fractions per week
• Total Dose 45 Gy
• MRI 3times Dx, the first of BT and 3 months
• With CT/MR applicator
• Fletcher or Vienna CT/MR applicator

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Pathway of transportation
CT room
Loading room
50 m
50 m
Theater
MRI room
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• First BT application
• MRI
• Other applications
• CT
• Prescribed dose
• 4 x 7 Gy
• Image-based technique
• But D90 keep at least 7 Gy

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First patient MRI at diagnosis
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At 1st of BT
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Dose comparison of the first patient
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Second pt MRI at Diagnosis
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At first BT second pt
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Pre- and post- optimized plan
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Dose comparison of second patient at first MRI
Parameters Pre optimized dose (Gy) Post optimized dose (Gy)
HR-CTV 18.1 9.3
Bladder 11.5 5.9
Rectum 8.3 4.4
Sigmoid 10.2 5.3
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Toxicities

• Due to short follow-up
• First patient (stage IIIB)
• Pulmonary metastasis
• Second patient (stage IIB)
• 2 month after treatment

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In accidental condition
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In some specials condition

• Patient age 54 yr
• Post subtotal hysterectomy
• CA cervix stage IIB
• Boost with ICBT

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In special conditionISBT
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Conclusions

• Image-guided planning
• CT/MRI imaging can be used to identify Target
  Volumes, When compared with 2D image
• Allow to optimization
• Allow to improve coverage of HR-CTV
• Allow to improve doses of bladder, rectum and
  sigmoid colon
• Allow to help us to treat special conditions and
  avoid some accidental situations

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However uncertainties

• Applicator reconstruction
• Inter-application variation
• If imaging is not performed for every insertion
• Inter-fraction variation
• If two or more fractions are based on one
  insertion and one treatment plan
• Variation between imaging and dose delivery
• LDR and PDR brachytherapy
• Fractionated HDR brachytherapy

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In Room Imaging in brachytherapy

• In Room for Brachytherapy (space)
• applicator in the patient
• adjacent structures to be defined GTV, CTV,OAR
• In Room imaging any imaging with applicator in
  place
• In Room for Brachytherapy (time)
• At the time of Brachytherapy
• In Room imaging imaging with applicator in place
  Plus during irradiation

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THANK YOU FOR YOUR ATTENTION