Transcript Three-dimensional Imaging for High Dose Rate Cervical

Lauren Hein
In partial fulfillment of RT 412
University of Wisconsin-La Crosse
Radiation Therapy Program
Background1,2,3
Cervical cancer is the third most
common cancer in women worldwide
 Current standard of care for early stage
node positive or locally advanced
cervical cancer is external beam
radiation therapy with concurrent
chemotherapy, followed by high dose
rate cervical brachytherapy

 Intracavitary cervical brachytherapy uses
tandem and ovoid applicators

Organs at risk: bladder, rectum and sigmoid
colon2
 Move around the implanted applicators daily so
localization and dose verification is a crucial part of
treatment planning4


Success of brachytherapy depends on
accurate identification and localization of the
uterus, cervix, and residual disease, as well as
accurate placement of tandem and ovoid
within the uterine canal3
Knowing the OAR movement can help to limit
the uncertainties and potentially detrimental
consequences of overdosing sensitive organs4
Orthogonal Images2,5

Historically, two-dimensional orthogonal xray images were used for treatment
planning
 Do not provide soft tissue visualization
○ Inadequate target coverage, insufficient dose
delivery, and a larger percentage of treatment
failure
○ Unknown PTV coverage and visibility, limited
opportunity for flexibility of dose distribution,
unknown spatial relationship between applicator
and surrounding OAR
 Benefit: radiation therapists do not need special
training or further education to use the machines
and create adequate images
Three-dimensional Imaging2,4,5
Delineate the soft tissue around the
applicators
 Localize the disease site
 Visualize the PTV
 Identify the OAR
 Alter the target volume dose coverage to
be more conformal for each individual
patient


Visualization of the tumor and adjacent
organs2
 Improved target coverage
 Local control
 Reduced late toxicity
Computed Tomography1,8

Three-dimensional CT vs. twodimensional imaging
 Improved local and regional relapse free
survival after treatment
 Decrease in grade 3+ urinary and
gynecologic toxicities
○ Urinary frequency, urgency, dysuria,
hematuria, and pelvic pain
 Increases diagnosis of uterine perforation
and avoids overtreatment of the fundus and
lower uterine segment
CT Benefits1,10
 Confirmation of applicator placement
 Decreased OAR dose for patients with a
small cervix
 Accountability for sigmoid colon dose and
reducing tissue toxicity
 Improved coverage for large volume disease
while maintaining organ dosimetry
CT Limitations5

Over-estimating of tumor volumes, resulting in an
increased dose delivered to the adjacent normal
tissue
 Less useful for PTV definition than MRI because it
overestimates the treatment volume width, leading to
irradiation of more normal tissue


Lack the ability to accurately assess nodal
metastases, which may lead to an underdose to the
gross disease and result in a worse prognosis
Image is taken first, and then the patient is
transported to HDR room, making it challenging to
ensure applicator position stability due to patient
movement
Magnetic Resonance Imaging5,7,9
Offers enhanced anatomy and tumor
recognition when used for treatment
planning
 CT images only provide limited soft tissue
definition in the are of interest, while MRI
offers a greater soft tissue definition
 Capable of assessing the tumor size within
an accuracy of 0.5cm and are capable of
assessing parametrial extension

MRI limitations7,9





Extremely expensive and difficult to access for many
clinical centers
Not suitable for patients with implanted metal
devices
Individuals with severe claustrophobia or obesity
may have difficulty
Lack the ability to accurately assess nodal
metastases, which may lead to an underdose to the
gross disease and result in a worse prognosis
Image is taken first, and then the patient is
transported to HDR room, making it challenging to
ensure applicator position stability due to patient
movement
Ultrasound1,7
Trans-abdominal ultrasound is cost
effective, widely available, and has been
found to have no significant differences
in dosimetry compared to MRI planning,
with 90% local control rate for cervical
brachytherapy
 May be substituted for MRI in defining
target volume, outlining the cervix and
uterus, and planning and verifying for
conformal treatment

Ultrasound Benefits6,7,9




Can be used to select appropriate applicator
size and to guide tandem and ovoid placement
during procedure
Decreases rate of uterine perforation because
of real time imaging
Accessible, portable, and able to be used
within the brachytherapy suite, eliminating the
need to move the patient during the procedure
Non-ionizing, quick and offers real time intraoperative anatomy assessment, reducing dose
to OAR while not compromising target volume
dose
Ultrasound Limitations6,7,9
Machine needs physical contact with the
patient, which creates the potential for
tissue deformation
 Needs an experienced operator
 No three-dimensional coordinate system or
fixed frame of reference to help define the
spatial location of the anatomy being
viewed
 Does not offer volumetric analysis of the
target coverage or dose to the surrounding
organs, which is crucial in the treatment
planning process

Future Advances1

Multi-institutional international trial
(EMBRACE) is underway to establish a
standard for cervical cancer
management in terms of tumor control,
complications, dose specification, and
prospective assessment of quality of life
 Trial anticipates to advance image based
brachytherapy and optimize its outcomes,
hopefully by mandating the use of soft tissue
three-dimensional imaging for treatment
planning
“BodyTom”12
Portable CT scanner which can be
transported from room to room, allowing
it to be used for verification of the
applicator and implanted catheter
positions before treatment delivery
everyday, without having to physically
move the patient
 Will help to eliminate any error or
uncertainty caused by patient
transportation during the procedure

Conclusion6,7
Traditional orthogonal x-ray imaging
remains the most commonly used imaging
modality for planning cervical
brachytherapy treatments in areas where
incidence of cervical cancer is high
 Incorporating soft tissue three-dimensional
imaging into brachytherapy programs is a
slow process due to the decreased
availability of planning software, increased
cost, and lack of optimal training

Three-dimensional image treatment
planning improves the technical accuracy
of implants, leading to improved local
control and decreased toxicity6
 Ideally, an imaging modality should be
available for each brachytherapy fraction,
and provide good organ and applicator
definition with the ability to delineate
residual tumor6
 This modality should have good soft tissue
imaging capabilities, be widely available,
portable, and economically attainable6

References
1. Vargo JA, Beriwal S. Image-based brachytherapy for cervical cancer. World Journal of Clinical Oncology. 2014;5(5):921-930. doi: 10.5306/wjco.v5.i5.921.
2. Madan R, Pathy S, Subramani V, et al. Comparative evaluation of two-dimensional radiography and three-dimensional computed tomography based dose-volume parameters
for high-dose-rate intracavitary brachytherapy of cervical cancer: A prospective study. Asian Pacific Journal of Cancer Prevention. 2014;15(11):4717-4721. doi:
10.7314/APJCP.2014.15.11.4717
3. Banerjee R, Kamrava M. Brachytherapy in the treatment of cervical cancer: A review. International Journal of Women’s Health. 2014;6:555-564. doi:10.2147/IJWH.S46247
4. Mazeron R, Champoudry J, Gilmore J, et al. Intrafractional organs movement in three-dimensional image-guided adaptive pulsed-dose-rate cervical cancer brachytherapy:
Assessment and dosimetric impact. Brachytherapy. 2015;14(2):260-266. doi: 10.1016/j.brachy.2014.11.014.
5. Pouliot J, Sloboda R, Reniers B. Two-, three-, and four- dimensional brachytherapy. In: Venselaar JLM, Baltas D, Meigooni AS, Hoskin PJ, eds. Comprehensive
Brachytherapy: Physical and Clinical Aspects. 1st ed. Boca Raton, FL: CRC Press; 2013
http://books.google.com/books?id=jm_RBQAAQBAJ&pg=PA117&source=gbs_toc_r&cad=4#v=onepage&q&f=false Accessed February 26, 2015:117-137.
6. Dyk SV, Schneider M, Chennakesavan S, et al. Ultrasound use in gynecologic brachytherapy: Time to focus the beam. [published online ahead of print January 22, 2015].
Brachytherapy. doi: 10.1016/j.brachy.2014.12.001.
7. Dyk SV, Chennakesavan SK, Schneider M, et al. Comparison of measurements of the uterus and cervix obtained by magnetic resonance and transabdominal ultrasound
imaging to identify the brachytherapy target in patients with cervix cancer. International Journal of Radiation Oncology, Biology, Physics. 2014;88(4):860-865. doi:
10.1016/j.ijrobp.2013.12.004
8.Katz A, Eifel PJ. Quantification of intracavitary brachytherapy parameters and correlation with outcome in patients with carcinoma of the cervix. International Journal Radiation
Oncology, Biology, Physics. 2000;48(5):1417–1425. PMID:11121642. Accessed February 26, 2015.
9. Dyk SV, Narayan K, Fisher R, Bernshaw D. Conformal brachytherapy planning for cervical cancer using transabdominal ultrasound. International Journal of Radiation
Oncology, Biology, Physics. 2009;75(1):64-70. doi: 10.1016.j/ijrobp.2008.10.057.
10. Holloway CL, Racine ML, Cormack RA, et al. Sigmoid dose using 3D imaging in cervical-cancer brachytherapy. Radiotherapy and Oncology. 2009;93(2):307-310. doi:
10.1016/j.radonc.2009.06.032.
11. Haie-Meder C, Pötter R, Van Limbergen E, Briot E, De Brabandere M, Dimopoulos J, Dumas I, Hellebust TP, Kirisits C, Lang S, et al. Recommendations from Gynecological
(GYN) GEC-ESTRO Working Group (I): Concepts and terms in 3D image based 3D treatment planning in cervix cancer brachytherapy with emphasis on MRI
assessment of GTV and CTV. Radiotherapy and Oncology. 2005;74(3):235–245. PMID:15763303. Accessed February 26 2015.
12. BodyTom. NeuroLogica Web Site. http://www.neurologica.com/products/bodytom 2012. Accessed February 10, 2015.
13. Aubry JF, Cheung J, Morin O, et al. Investigation of geometric distortions on magnetic resonance and cone beam computed tomography images used for planning and
verification of high-dose rate brachytherapy cervical cancer treatment. Brachytherapy. 2010;9(1):266-273. doi:10.1016/j.brachy.2009.09.004.