Download Prostate Brachtherapy - Alabama Cancer Congress

Trina Lynd, M.S.
Medical Physicist
Lifefirst Imaging & Oncology
Cullman, AL
Tri-State Alabama, Louisiana and
Mississippi Spring 2016 Meeting
April 17, 2016
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Discuss permanent prostate brachytherapy and
its role in the treatment of prostate cancer
Identify physics processes involved in the
execution of a permanent prostate
brachytherapy case
Present useful resources, documents and
reports to use as references
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Prostate Cancer is the 2nd most common
cancer in American men, following skin
cancer
Prostate Cancer is the 2nd leading cause
of death in men, following lung cancer
Statistics taken from American Cancer Society’s website www.cancer.org
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Radical Prostatectomy
External Beam Radiation Therapy
Temporary & Permanent Brachytherapy
Androgen Deprivation Therapy
Watchful waiting or active surveillance
Cryotherapy
Vaccine treatment
Bone directed treatment
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Taken from American Cancer Society’s website www.cancer.org
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American Cancer Society’s estimates for
prostate cancer in 2016
180,890 new cases
 26,120 deaths
 1 of 7 men will be diagnosed with prostate cancer
 6 of 10 men diagnosed will be > 65
 1 of 39 men will die of prostate cancer
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Statistics taken from American Cancer Society’s website www.cancer.org
SURVIVAL FOR ALL
STAGES
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5 year almost 100%
10 year 98%
15 year 95%
SURVIVAL BROKEN
DOWN INTO DISEASE
LOCATIONS
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Localized almost 100%
Regional almost 100%
Distant 28%
Statistics taken from American Cancer Society’s website www.cancer.org
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Low Risk: Gleason score < 6, PSA < 10ng/mL,
tumor classification T1 or T2a
Intermediate Risk: Gleason score 7 or PSA > 10
ng/mL<20ng/mL or T2b, T2c
High risk: Gleason score 8-10 or PSA
>20ng/mL or T3a
Seminal vesicle involvement T3b high risk in
evaluation and treatment
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Permanent prostate brachytherapy is an outpatient
procedure with rapid recovery and quick (within
several days) return to normal activity.
Historically prostate brachytherapy consisted of freehand placement of seeds in an open surgical procedure
using retropubic approach.2
‘Modern’ prostate brachytherapy utilizing Iodine-125
(125I) with transrectal ultrasound (TRUS) & template
pioneered around early 1980’s.3
FAVORABLE INDICATORS4
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Life expectancy > 5 - 10years
T1b – T2c & some T3
Gleason scores 2 -10
PSA < 50 ng/mL
No pathological lymph
nodes
No distant metastases
UNFAVORABLE INDICATORS4
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Unsuitability for general
anesthesia
Severe urinary irritative/
obstructive symptoms
Extensive TURP defect
Large median lobe
Large prostate size
Pubic arch interference
Gross Seminal Vesicle
involvement
Prior pelvic radiation
Inflammatory bowel disease
Pathologic involvement
pelvic lymph nodes
Metastatic disease
Table 4 from American Brachytherapy Society Consensus Guidelines for Transrectal Ultrasound Guided Permanent
Prostate Brachytherapy, Brachytherapy 11 (2012)
Table 6 from American Brachytherapy Society Consensus Guidelines for Transrectal Ultrasound
Guided Permanent Prostate Brachytherapy, Brachytherapy 11 (2012)
137Cs
was introduced in 2004
Historically 198Au was used but not recommended
at present time
125I
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Monotherapy: 145 Gy
Boost: 108-110 Gy with
41.4 Gy – 50.4 Gy of
External Beam
Radiation Therapy
103 Pd
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Monotherapy: 125 Gy
Boost: 90 – 100Gy with
41.4 Gy – 50.4 Gy of
External Beam
Radiation Therapy
125I
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Air Kerma 0.4 - 1.0U or
0.3 – 0.8 mCi2
RTOG clinical trials 0.23
– 0.43mCi3
90% of dose delivered in
197 days2
103Pd
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Air Kerma 1.4 – 2.2U or
1.1 – 1.7 mCi2
RTOG clinical trials 1.0
– 2.0 mCi3
90% of dose delivered in
56 days2
American Brachytherapy Society does not recommend a
seed activity or total activity3
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NOTE SEED ACTIVITY UNITS WHEN
ENTERING INTO THE TREATMENT
PLANNING COMPUTER!
Air Kerma Strength Conversions
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1 uGy m2/h (U) = 0.787 mCi for 125I
1 uGy m2/h (U) = 0.773 mCi for 103Pd
1 uGy m2/h (U) = 0.348 mCi for 137Cs
LOOSE SEEDS
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Mick applicator uses
seeds preloaded into a
cartridge on site or by
vendor
Pre-loaded in needles
on-site or by vendor
STRANDED SEEDS
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Bard QUICKLINKED®
sources
Amersham Rapid
StrandTM
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AAPM TG56 recommends 10% of seeds
assayed prior to implantation
Seeds can be assayed in bulk or mick cartridges
A single calibrated seed from same batch can
be sent with seeds which are sent in preloaded
needles, sutured/sterile strands
Autoradiographs
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Seeds need to be sterilized before loading
Loose seeds can be loaded into Mick cartridges
and then sterilized
Sterilization methods:
Autoclave
 Flash sterilization
 Steam sterilization
 Ethylene oxide gas required for seeds in sutures
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“American Brachytherapy
Society acknowledges that the
nature of permanent prostate
brachytherapy precludes exact
precision in final seed
placement and consequently a
wide range of post plan
variability is not only accepted
but expected”3
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Preplan prior to scheduled OR case
Patient positioning must be reproducible
in OR
Treatment plan generated to determine:
 # of needles
 Needle locations on template
 # of seeds
 Strength of seeds
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Transrectal ultrasound images preferred
method for imaging, MRI acceptable
Image 2-3 weeks prior to case to limit
changes in prostate volume
Axial images 5mm intervals from base to
apex
Check for public arch inference
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Transrectal ultrasound 3D images acquired in
OR under anesthesia
Patient in same position throughout whole
procedure
Adjustments can be made to optimize
positioning rectum and pubic arch
Acquire images at 5mm intervals
Nomogram table used to double check
planning parameters
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Contour prostate, bladder, rectum, urethra,
seminal vesicles with patient in actual
treatment position
Create treatment plan while patient is prepped
Obtain assistance and approval from Radiation
Oncologist immediately
Guide and monitor placement of needles and
seeds with ultrasound
Monitor migration of seeds
Monitor swelling of prostate
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Uniform loading – 1 cm apart center-to-center
requires higher seed count using decreased
strength
Modified peripheral loading – some seeds
deleted from center to decrease central dose
Peripheral loading – seed limited to periphery
requiring higher seed strength
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General or spinal anesthesia
Dorsal lithotomy position with elevation of
legs in stirrups with upper thighs at right angle
Rectum cleaned out, hopefully with enema
prior
Alignment of ultrasound probe with prostate
and rectum
Posterior edge of prostate needs to be in close
proximity to last row on template
Good visualization of urethra
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Transrectal Ultrasound Imaging favored for
preplanning and intraoperative planning
Ultrasound with longitudinal and sagittal
views provides visualization of prostate base
and apex
Verify perineal template grid and electronic
grid coincide
Easy visualization of rectum
Urethra can be visualized most of time with
catheter in place. Aerated gel placed into
catheter improves visualization tremendously
AAPM Recommendations on Dose Prescription and Reporting Methods for Permanent
Interstitial Brachytherapy for Prostate Cancer: Report of AAPM Task Group 137
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MRI good imaging tool for preplanning and post
planning
Soft tissues easily visualized
MRI can be merged with ultrasound and CT to
improve target delineation
MRI is not as commonly used as other modalities
for permanent prostate brachytherapy
AAPM Recommendations on Dose Prescription and Reporting Methods for Permanent Interstitial
Brachytherapy for Prostate Cancer: Report of AAPM Task Group 137
AAPM Recommendations on Dose Prescription and Reporting Methods for Permanent Interstitial
Brachytherapy for Prostate Cancer: Report of AAPM Task Group 137
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CT commonly used for post implant planning
Delineating the prostate is extremely difficult
particularly with seeds in place
CT prostate volumes tend to be overestimated
which result in lower plan doses
CT on Day 0 or 1 convenient for patient, early
detection of problems
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Post implant edema large factor in post implant
evaluations
Edema is most apparent the days immediately
following procedure
Edema can be as great as 40-50%
ABS recommendations for timing of post
planning CT is dependent upon radionuclide
used
 125I
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30±7 days
103Pd 16±4 days
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Development of D90 concept by Stock and peers
“Minimum dose received by the “hottest” 90%
of the prostate volume, also described as
isodose line enclosing 90% of prostate.”3
Many studies have shown that D90 and V100 are
correlated with outcomes3
AAPM Recommendations on Dose Prescription and Reporting Methods for Permanent Interstitial
Brachytherapy for Prostate Cancer: Report of AAPM Task Group 137
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So many parameters being followed
ABS postoperative dosimetry
recommendations3
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D90
V100
V150
UV150
UV5
UV30
RV100
expressed in Gy and %
expressed in %
expressed in %
expressed in volume
expressed in %
expressed in %
expressed in cc
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Image based volumetric plan
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CT, MRI, ultrasound or a combination
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Slice thickness ≤ 5mm
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3D isodose planning
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DVH analysis
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1. American Cancer Society website www.cancer.org
2. Permanent prostate seed implant brachytherapy: Report
of American Association of Physicist in Medicine Task
Group No. 64
3. American Brachytherapy Society consensus guidelines
for transrectal ultrasound guided permanent prostate
brachytherapy, Brachytherapy 11(2012)
4. Dosimetry of interstitial brachytherapy sources.
Recommendations of the AAPM Radiation Therapy
Committee Task Group No. 43
5. Code of practice for brachytherapy physics: Report of the
AAPM Radiation Therapy Committee Task Group No. 56
6. AAPM Recommendations on Dose Prescription and
Reporting Methods for Permanent Interstitial Brachytherapy
for Prostate Cancer: Report of AAPM Task Group 137