Radiotherapy planning in carcinoma cervix dr rekha

Radiotherapy planning in
carcinoma cervix
Dr. Rekha Arya
SR .RADIOTHERAPY DEPT
MAMC

CONFORMAL THERAPY
It is described as radiotherapy
treatment that creates a high dose
to the desired target volume
while minimizing the dose to
critical normal tissues.

Figure: differences between
(a. conventional radiotherapy,
(b. conformal radiotherapy
(CFRT) without intensity-
modulation and
(c. CFRT with intensity
modulation (IMRT).

RATIONALE OF USING IMRT IN CA Cx
• Conventional RT → toxicities due to the inclusion of
considerable volumes of various normal tissues
• Small bowel → diarrhea, SBO, enteritis, malabsorption
• Rectum → diarrhea, proctitis, rectal bleeding
• Bladder → urgency, dysuria, haematuria,
• Bone Marrow → ↓WBC, ↓platelets, anemia
• Reduction in the volume of normal tissues irradiated with
IMRT may thus ↓risk of acute and chronic RT sequelae
• Allow for simultaneous boost of involved lymph nodes

POSITIONING
• Important component of conformal RT.
• Patients may be positioned in
 Supine position
 Prone position with belly board
• supine position is preferred because
 Most comfortable
 Reproducible position
 Stabilizes pelvis
 Can be combined with immobilization device.
• For this purpose positioning devices may be used
• Positioning devices are ancillary devices used to help maintain the patient in a
non-standard treatment position.
• knee rest can be used
 Relaxes lower back making pt. more comfortable
 Minimize rotation of pelvis
 Knee rest with indexing limits superior-inferior and lateral motion

Prone position on a belly
board
 Belly Board is used to allow
the intestinal tract to drop out of treatment field.
 Made of foam material has a low absorption of the beam.
 In hysterectomy pts:
• small bowel may drop into the pelvic area so prone position
may be beneficial
 For patients with an intact cervix, the small bowel often lies
superior to the uterus and above the pelvic brim, creating less
need to shift the bowel out of the pelvis.

TIMO
Face rest
Breast board
Knee wedge
Belly board
PITUITARY BOARD

IMMOBILIZATION
• Patient is immobilized using individualized casts or
moulds.
• An immobilization device is any device that helps to
establish and maintain the patient in a fixed, well-
defined position over a course of radiotherapy
treatment everyday.

Immobilization
 Thermoplastics form the basis for immobilization in head and neck
 In the pelvis these are difficult to be used as:
 Lack of bony points for fixation
 Continuing abdominal movements with respiration
 Presence of fat pads and folds
 simple supine positioning with skin markings:
 Cheap
 Reproducible
 Ease of use and comfortable for patient.

IMAGE ACQUISITION
It provides foundation
for treatment planning
Usually more than one
imaging modalities are
required for better
delineation of target
volume
Images are acquired for :
Treatment planning
Image guidance and/or treatment
verification
Follow-up studies (during & after
treatment)

Need of contrast during simulation
• Usually not needed in CT simulation
• because structures can be contoured
even without contrast on CT.
• May be helpful in conventional simulation
to enhance the soft-tissue detail
• contrast may be placed at following sites
 iv contrast to localize the pelvic vessels
 oral contrast to delineates small bowel.
 Foley’s catheter with bladder contrast
 barium in the rectum,
 vaginal tube in the vagina,

IMAGE ACQUISITION
• CT is done with pt in the treatment position with immobilization
device if used.
• Radio opaque fiducial are placed .
• These fiducial assist in any coordinate transformation needed as
a result of 3D planning and eventual plan implementation.
• A topogram is generated to insure that patient alignment is
correct & then using localizer, area to be scanned is selected.
• The FOV??? is selected to permit visualization of the external
contour, which is required for accurate dose calculations.
• Using site dependent protocols, images are acquired.
• The planning CT data set is transferred to a 3D-TPS or
workstation via a computer network.

IMAGING MODALITIES
• No single imaging modality produces all the
information, needed for the accurate identification
and delineation of the target volume and critical
organs.
• Various imaging modalities used are :
– CT
– MRI
– PET-CT

High Tech Diagnostic Machines
CT Simulator
PET Scan
MRI

CT SIMULATOR
• Images are acquired on a
dedicated CT machine called
CT simulator with following
features
– A large bore (75-85cm) to
accommodate various treatment
positions along with treatment
accessories.
– A flat couch insert to simulate
treatment machine couch.
– A laser system consisting of
• Inner laser
• External moving laser
to position patients for
imaging & for marking

TREATMENT PLANNING SYSTEM
• TPS provides tools for
– Image registration
– Image segmentation or contouring
– Virtual Simulation
– Dose calculations
– Plan Evaluation
– Data Storage and transmission to console
– Treatment verification

VOLUMES
• The International Commission on Radiation Units and
Measurements (ICRU),( inception in 1925,)has its principal
objective the development of internationally acceptable
recommendations .
• There are different type of ICRU reports for different type of
procedure like:
• ICRU 38 (1985) - "Dose and Volume Specification for Reporting
Intracavitary Therapy in Gynecology“
• ICRU 50 (1993) - "Prescribing, Recording, and Reporting Photon
Beam Therapy“
• ICRU 58 (1997) - interstitial brachytherapy
• ICRU 62 (1999) - "Prescribing, Recording and Reporting Photon
Beam Therapy (Supplement to ICRU Report 50)"

ICRU 50 & 62
• When delivering Radiotherapy treatment, parameters such as
volume & dose have to be specified for:
– Prescription
– Recording
– Reporting
• Such specifications serve a number of purposes
– To enable the Radiation Oncologist to maintain a consistent treatment
policy and improve it in the light of experience.
– To compare the results of treatment and benefit from other
departmental treatments.
– It is particularly important in multi-center studies in order to keep
treatment parameters well defined, constant & reproducible.
• It is expected that rapid development of new techniques would
increase the complexity of radiotherapy and emphasize the
need for general strict guidelines.

 Gross Tumor Volume (GTV): Gross palpable or visible/demonstrable extent and
location of malignant growth. This may consist of primary tumor, metastatic
lymphadenopathy.
 Clinical Target Volume (CTV): Anatomical concept. GTV + sub clinical microscopic
disease.
 The PTV (planning target volume) - Geometrical concept defined to select
appropriate beam sizes and beam arrangements.
• It considers the net effect of the geometrical variations to ensure that the
prescribed dose is actually absorbed in the CTV.
• These variations may be intra-fractional or inter-fractional due to number of
factors like
1. Movement of tissues/patient.
2. Variations in size & shape of tissues.
3. Variations in beam characteristics.
4. The uncertainties may be random or systematic.

 Treated Volume: Volume enclosed by an isodose surface (e.g. 95% isodose),
selected and specified by radiation oncologist as being appropriate to achieve
the purpose of treatment.
 Ideally, Treated Volume would be identical to PTV, but may also be
considerably larger than PTV.
 Irradiated Volume: Tissue volume which receives a dose that is considered
significant in relation to normal tissue tolerance. Dose should be expressed
either in absolute values or relative to the specified dose to the PTV.

Organs at Risk
 Organs at Risk: Normal tissues whose radiation sensitivity may significantly
influence treatment planning and/or prescribed dose.
• Any possible movement of the organ at risk as well as uncertainties in the
setup during the whole treatment course must be considered.
• Organs at risk may be divided into three different classes:
– Class I (Radiation lesions are fatal & result in severe morbidity.)
– Class II (Result in moderate to mild morbidity.)
– Class III (Radiation lesions are mild, transient and reversible or result in
no significant morbidity.)
9/25/2010

Organs at Risk
OARs
• Lungs
• Spinal Cord

ICRU 62 (1999) - "Prescribing, Recording and Reporting Photon
Beam Therapy (Supplement to ICRU Report 50)“
• No change to definition of GTV and CTV, since they are oncologic
concepts independent of any technical development
• Global concept and definition of PTV is not changed, but
definition is supplemented
• Internal Margin (IM): Variations in size, shape, and position of
the CTV relative to anatomic reference points; e.g., filling of
bladder, movements of respiration. The internal variations are
physiological ones, and result in change in site, size, and shape of
the CTV
• Internal Target Volume (ITV): Volume encompassing the CTV and
IM. (ITV = CTV + IM)

Set up Margin (SM):
• It accounts for the uncertainties in patient positioning and aligning of
therapeutic beams.
• The uncertainities may vary with selection of beam geometries, and may
depend on variations in patient positioning, mechanical uncertainities of
the equipment (e.g. sagging of gantry, collimators, or couch), dosimetric
uncertainities, transfer setup errors from CT simulator to treatment unit,
and human factors.
Planning organ at risk volume (PRV):
• An integrated margin must be added to the OR to compensate for
variations including the movement of organ as well as setup uncertainties.
• In particular the internal margin & the setup margin for the OR must be
identified. This leads to the concept of PRV.
9/25/2010

IM = Internal Margin
SM = Setup Margin
IM
CTV
SM
PRV
OR
ICRU 62 – Volume definitions
ITV
PTV
9/25/2010

ICRU 62 report
Target volumes
•GTV = Gross Tumour Volume
= Macroscopic tumour
•CTV = Clinical Target Volume
= Microscopic tumour
•PTV = Planning target Volume
PTV
Advice: Always use the
ICRU reports to specify and
record dose and volume
Baumert et al. IJROBP 2006 Sep 1;66(1):187-94

Target Volume delineation
 For definitive treatment of carcinoma cervix with conformal
radiation techniques, accurate target delineation is vitally
important,
 Various guidelines for CTV delineation are published in the
literature yet a consensus definition of clinical target volume
(CTV) remains variable
 Clinical judgement remains the most important aspect of
determining the target volumes

Contouring
Several contouring guidelines available for CTV
 Taylor et al pelvic nodal delineation (CT based)
 Toita et al for CTV delineation in intact cervix EBRT (CT based)
 Lim et al for CTV delineation in intact cervix IMRT (MRI based)
 Small et al for CTV delineation in post operative IMRT (CT based)
 PGI literature review & guidelines for delineation of CTV for intact
carcinoma cervix (CT based)
Guidelines for organ at risk
 Pelvic Normal Tissue Contouring Guidelines for Radiation Therapy: A
Radiation Therapy Oncology Group Consensus Panel Atlas (CT based)

Components of CTV
The group consensus was
that entire uterus should be
included in the CTV
because:
• Uterus & cervix are
embryologically one unit
with interconnected
lymphatics and no clear
separating fascial plane.
• Determination of
myometrial invasion can
be difficult.
• uterine recurrences
have been reported
(2%), but exact location
of these recurrences
(fundal vs. corpus) have
not been stated.

uterus
parametrium
rectum
Sigmoid colon

superior boundaries of parametria
are at the top of the fallopian tube,
and contours should stop once
loops of bowel are seen next to the
uterus as this is clearly above the
broad ligament.
For the very anteverted uterus,
particularly where the fundus lies
below the cervix, the parametrial
volume should stop once the
cervix is seen
Inferiorly, the parametrial tissue
finish at the muscles of the pelvic
floor.
Parametrial Contouring Guidelines

Anteriorly boundary lies at the posterior wall of
the bladder. Bladder or In patients with a very
small bladder (which lies deep in the pelvis),
posterior border of the external iliac vessel.
Posteriorly: bounded by the mesorectal fascia
and uterosacral ligaments parametrial volumes
would extend up to the rectal contour in
advances stages.
Laterally, the parametrial volume should
extend to the pelvic sidewall (excluding
bone and muscle).
some overlap of this volume with nodal
CTV, particularly along the obturator strip

Taylor A, Rockall A, Powell M. An Atlas of the Pelvic Lymph Node Regions to Aid Radiotherapy Target Volume Definition.
Clinical Oncology. 2007 Sep ;19(7):542-550.

lateral external iliac
nodes (blue),
 inguino-femoral nodes
(green)
 parametria and upper
vagina (red).
pre-sacral (PS), internal
iliac (II),
obturator (Obt),
lateral (EIl), medial(EIm)
and anterior (EIa) external
iliac,
 parametrial and
paravaginal (Pm),

1. CTV definition for the post-operative therapy of endometrial and cervical
cancer should include the common, external, and internal iliac lymph node
regions.
2. The upper 3.0 cm of vagina and paravaginal soft tissue lateral to the vagina
should also be included.
3. For patients with cervical cancer, or endometrial cancer with cervical
stromal invasion, it is also recommended that the CTV include the presacral
lymph node-region

Post-operative CTV delineation (Small
et al)

External & Internal iliac
External & Internal iliac
Presacral

External & Internal Iliacs
Paravaginal
External & Internal iliacs
Presacral

Vagina & Paravaginal Tissues
Vagina

 The aim of the article was to review the guidelines for CTV delineation
published in the literature and to present the guidelines practiced at their
institute
 6 articles : 2 articles from Taylor et al and Toita et al and 1 from Small et al.,
Lim et al., were reviewed
 The CTV in cervical cancer consists of the CTV nodal and CTV primary.
 CTV nodal consists of common iliac, external iliac, internal iliac, pre-sacral
and obturator
 group of lymph nodes, and CTV primary consists of the gross tumor
volume, uterine cervix, uterine corpus, parametrium, upper third of vagina
and uterosacral ligaments.
 Pelvic LN CTV is contoured in accordance with the latest Taylor’s guidelines
with some modifications
 This was the first report to provide the complete set of guidelines for
delineating both the CTV primary and CTV nodal in combination

Normal Tissue Delineation (RTOG)
• Bowel: The small and large bowel can be contoured together as a
Bowel-Bag.
• Inferiorly, the bowel bag should begin with the first small or large
bowel loop or above the ano-rectum, whichever is most inferior.
• The contours should end 1 cm. above the PTV .
• Ano-Rectum: Ano-Rectum should be contoured from the level of
the anus to the sigmoid flexure. It should extend from the anal verge
(marked by a radiopaque marker at simulation) to superiorly where
it loses its round shape in the axial plane and connects anteriorly
with the sigmoid.
• Bladder: Contoured inferiorly from its base, and superiorly to the
dome.
• Femoral Heads:The ball of the femur, trochanters, and proximal
shaft to the level of the bottom of ischial tuberosities
Gay HA, Barthold HJ, O′Meara E, Bosch WR, El Naqa I, Al-Lozi R, et al. Pelvic normal tissue
contouring guidelines for radiation therapy: A Radiation Therapy Oncology Group consensus panel
atlas. Int J Radiat Oncol Biol Phys 2012;83:e353-62.

• To evaluate the toxicity and clinical outcome in patients with LACC
treated with WP-CRT versus WP-IMRT
• METHODS AND MATERIALS:
• Between January 2010 and January 2012,
• 44 patients with (FIGO 2009) stage IIB-IIIB SCC cervix randomized to receive
50.4 Gy in 28 fractions delivered via either WP-CRT or WP-IMRT with
concurrent weekly cisplatin 40 mg/m2 followed by high-dose-rate HDR) IICRT, 7
Gy to point A in 3 once-weekly sessions
• In patients deemed unsuitable for ICRT, interstitial brachytherapy (IBT) 10 Gy in
2 once-weekly sessions based on our previous experience
• Acute toxicity : graded according to the CTCAE version 3.0
• Late toxicity: graded according to RTOG
• Primary end point :acute gastrointestinal toxicity
• secondary endpoints: disease-free survival

The median time to completion of treatment in the WP-CRT arm was 9.1
weeks(range, 8.3-12.9 weeks), and in the WP-IMRT arm it was 9.1 weeks (range,
8.3-11.7 weeks).
The median number of chemotherapy cycles in both arms was 5 (range, 3-6).
The median follow-up time
in the WP-CRT arm was 21.7
months (range, 10.7-37.4 months),
in the WP-IMRT arm was 21.6
months (range, 7.7-34.4 months).

RESULTS
Patients in the WP-IMRT arm experienced significantly fewer grade ≥2 acute
gastrointestinal toxicities (31.8% vs 63.6%, P=.034) and grade ≥3
gastrointestinal toxicities (4.5% vs 27.3%, P=.047) than did patients receiving
WP-CRT

RESULTS:
At 27 months,
disease-free survival was 79.4% in the WP-CRT group versus
60% in the WP-IMRT group (P=.651)
overall survival was 76% in the WP-CRT group versus 85.7% in
the WP-IMRT group (P=.645).
CONCLUSION:
WP-IMRT is associated with significantly
less toxicity compared with WP-CRT and
has a comparable clinical outcome.
LIMITATION: small sample sizes and short
follow-up times.no use of image guidance

Caveats of IMRT
 Significantly increased expenditure:
 Machine with treatment capability
 Imaging equipment: Planning and Verification
 Software and Computer hardware
 Extensive physics manpower and time required.
 Immobilization: Patient setup must be accurate and reproducible
 Contouring: Need accurate contouring to avoid misses.
 Knowledge of Internal Motion: Margins could vary greatly
depending on organ motion
 Concerns with integral dose and secondary malignancy

RADIATION SIDE EFFECTS
Acute Side Effects:
Acute gastrointestinal side effects: include diarrhea, abdominal
cramping, rectal discomfort, and occasionally, rectal bleeding, which
may be caused by transient enteroproctitis.
Genitourinary symptoms:secondary to cystourethritis, are dysuria,
frequency, and nocturia,microscopic or even gross hematuria.
Skin reactions: erythema and dry or moist desquamation may develop
in the perineum or intergluteal fold.
acute radiation vaginitis, superficial ulceration of the vagina, and vagianl
stenosis can also occur

• Late Side Effects:
Late radiation effects are closely related to total doses given
to the pelvic organs.
• Retrovaginal or vesicovaginal fistula and proctitis or cystitis
can occur but in small percentages.
• Injury to the gastrointestinal tract usually appears within 2
years of radiation therapy
• Complications of the urinary tract more frequently are seen
3- 4 years after treatment.
• Vaginal stenosis is associated with dyspareunia
• Anal incontinence is observed occasionally

Dose limitation
• HDR: limit bladder and rectal points to <70% of point A dose with
HDR.
• LDR: limit rectal point <70 Gy and bladder point <75 Gy.
• Limit upper vaginal mucosa <120 Gy, midvaginal mucosa <80–90 Gy,
and lower vaginal mucosa <60–70 Gy.
• Vaginal doses >50–60 Gy cause significant fibrosis and stenosis.
• Ovarian failure with 5–10 Gy and sterilization with 2–3 Gy.
• Limit uterus <100 Gy, ureters <75 Gy, and femoral heads <50 Gy.

To be continued…….brachytherapy
thanks
t

Radiotherapy planning in carcinoma cervix dr rekha

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