Radiotherapy for bladder cancer part ii

Radiotherapy for Bladder Cancer (Part II)
Mohammed Fathy Bayomy, MSc, MD
Lecturer
Clinical Oncology & Nuclear Medicine
Faculty of Medicine
Zagazig University

Technique of Conventional Radiotherapy

(1) Initial (Large) Volume = Phase I (Induction)
• Simulator: conventional X-ray.
• Patient position: supine with arms on chest.
• Immobilization: knee and ankle rest
• Skin tattoo: placed over symphysis pubis & two lateral tattoos
placed over iliac crests to prevent lateral rotation and marked
by barium paste.
• Bowel preparation: rectum should be empty of flatus &
faeces.
• Bladder preparation: full bladder to ensure that in all possible
circumstances the PTV includes maximum extension of full
bladder.

• Cystogram: is performed on simulator with full bladder.
• Transverse outline: is performed at center of the volume to
help in dosimetry.
Or
• CT section: is taken at center of the volume to help in
dosimetry.

• Simulator: conventional X-ray.
• Patient position: supine with arms on chest.
• Immobilization: knee and ankle rest
• Skin tattoo: placed over symphysis pubis & two lateral tattoos
placed over iliac crests to prevent lateral rotation and marked
by barium paste.
• Bowel preparation: rectum should be empty of flatus &
faeces.
• Bladder preparation: empty bladder to ensure that tumor
remains within planned target volume.
(2) Boost (Small) Volume = Phase II (consolidation)

* To minimize the risk of geographic miss.
* To keep the treated volumes as small as possible
• Cystogram: is performed on simulator with empty bladder,
urinary catheter is inserted, 20 ml of contrast & 10 ml of air are
introduced into bladder without draining residual urine and AP
film is taken, following insertion of barium into rectum, lateral
film is obtained
• Transverse outline: is performed at center of the volume to
help in dosimetry.
Or
• CT section: is taken at center of the volume to help in
dosimetry.

(1) Initial (Large) Volume Phase I (Induction)
• Include primary tumor and its local extensions, whole bladder
and pelvic lymph nodes.
• The volume extends from upper border of L5 to include
common iliac nodes and inferiorly to cover the lower of the
obturator foramen, if the tumors involves the urethra, the
volume must extend inferiorly.
• The lateral margins lie 1 cm outside the bony pelvic walls.
• The anterior border lies 1-2 cm in front of anterior ladder wall
and posterior border at S2/3 junction encompass internal iliac
nodes and the entire bladder.

• Planning target volume include a margin of 1.5-2 cm around
bladder with a minimum 2-cm margin at tumor site to
encompass any extension.
• CT scanning is used to define target volume, which usually 8-
10 cm3.

• Superior border: at L4-L5 disc space
• Inferior border: below obturator foramen.
• Lateral: 1.5-2 cm to bony pelvis at its widest section
• Anterior border: 1.5 to 2 cm from most anterior aspect of bladder
• Posterior border: about 2.5-3 cm posterior to posterior aspect of
bladder.

• Entire bladder excluding nodes.
• Bladder + tumor with a 2-cm margin.

• 3 Field arrangement: anterior and opposing lateral wedged fields
are chosen to ensure homogenous dose distribution to target
volume with sharp cut-off posteriorly to spare rectum.
• 4 Field arrangement: anterior, posterior and opposing lateral
wedged fields (box) are chosen to ensure coverage of posterior
tumor extension or potential involvement of internal iliac nodes, it
achieve good homogeneity but may give a high rectal dose
depending on position of rectum. T is time-consuming.

• 3 Field arrangement: anterior and opposing lateral wedged fields.
• 3 Field arrangement: anterior and two posterior oblique wedged
fields (depend on contour). Angle between posterior oblique fields
is usually 110o to spare rectum.
• 2 Field arrangement: opposing anterior and posterior are chosen for
palliative treatment, as this arrangement is satisfactory for lower
doses of palliative irradiation to control hematuria in frail patients.

• Whole pelvic irradation: treatment is given with patient supine and
bladder full in order to displace small bowel out of pelvis.
• Small volume treatments: bladder is empty to minimize target
volume and to ensure that all tumor is included.
• Bladder volume: will inevitably vary from day to day because of
residual urine, this this variation may be reduced by asking patient
to empty their bladder immediately before treatment each day.
• Patient alignment: using anterior laser beam to check midline and
two lateral lasers to align lateral skin tattoo and prevent rotation.

• Field center is marked: with reference to tattoo over symphysis
pubis.
• Interplanar distance (IPD): is cheeked and pin depth measured from
treatment plan.
• Most plans are treated isocentrically, but in obese patient IPD may
vary widely from day to day, for whole pelvic treatment it may then
more accurate to measure the entry point of lateral fields from
couch top in order to avoid any discrepancy in pin depth and to treat
at 100 cm FSD.

44 Gy in 22 fraction given in 4.5 weeks.
64Gy in 32 fractions in 6.5 weeks
20 Gy in 10 fraction given in 2 weeks.
II- Palliative Treatment
35 Gy in 10 fractions in 2 weeks.
Or
21 Gy in 3 fractions given in 1 week.
I- Radical Treatment
40-45 (1.8-2Gy/f)
24 Gy (1.8-2 Gy/f)
64-64.8 Gy (1.8-2 Gy/f)

Technique of 3D Conformal Radiotherapy

1- CT simulation using 3 mm or less slice
2- Patient Position: supine with arms on chest.
3- Immobilization: knee and ankle rest. frog-leg positioning
may be warranted to reduce skinfolds.
4- Immobilization devices including Vak-Lok or Alpha Cradle
may be used and vary by institution.
5- Bowel preparation: rectum should be empty of flatus and
faeces, use of daily micro enemas may be considered.
6- IV contrast may be used to help guide GTV target &
vessels; A simulation scan from the upper lumbar spine to
mid-femur is recommended

7- Bladder preparation
• Empty bladder prior to scan.
• A new simulation may be helpful with a partially distended
bladder to limit dose to entire bladder as well as rectum
depending on the location of the tumor. Many institutions
continue the boost with the bladder empty since this provides
reproducibility.
• If using IMRT with image guidance, simulation is performed
with bladder partially full to allow for dose painting to GTV
daily.
• Bladder filling should be comfortable and reproducible by
patient. On board imaging capable of assessing bladder filling
and volume is critical to treating with a full bladder.

8- Image registration and fusion applications with previously
performed MRI and PET are recommended to help in
delineation of target volumes. However, bladder mapping
in conjunction with surgeon is imperative for CTV. Normal
tissues should be outlined on all CT slices in which
structures exist. CT urography may aid in target
delineation.

9- Image-guided radiation therapy allows for adjustments to
be made based on soft tissue anatomy prior to treatment
delivery. Cone-beam CT can be performed in an effort to
decrease uncertainty and therefore decrease treatment
margins. It also allows for confirmation of bladder filling.
While not the standard, IMRT is an option to reduce bowel
dose as well as spare uninvolved bladder during a boost.

Bladder protocol
to account
for organ motion

1- Patient is asked to void urine & empty
bladder as much as possible.
2- Patient is asked to drink 500 ml of water &
time is recorded.
3- After 60 minutes of drinking water, CT
simulation without contrast is performed
suggestive of full bladder.

4- Patient is asked to void urine & empty
bladder as much as possible & CT
Simulation with contrast
enhancement is performed suggestive
of empty bladder.

5- Both images (with full bladder & empty
bladder) are reviewed for tumor delineation
to ensure that in all possible
circumstances the PTV includes maximum
extension of full bladder. However CT
slices with empty bladder will form primary
image for GTV & CTV delineations.

Macroscopic tumor visible on radiological imaging/ cystoscopy
findings provided by urologist during TURBT
I- Gross Tumor Volume (GTV)
CT slices with empty bladder form primary image for GTV delineations.

II- Clinical Target Volume (CTV)
(1) CTV_Primary
GTV + whole bladder
In patient with tumors at bladder base, proximal urethra (in
both genders), & prostate + prostatic urethra(in males) to be
included in CTV
(2) CTV_Lymph node (CTV_LN)
External iliac lymph (including obturator).
Internal iliac (hypogastric) lymph nodes-, along its branches
(including presacral lymph).
CT slices with empty bladder form primary image for CTV delineations.

CTV_Primary + 1-1.5 isotropic margin.
III- Planning Target Volume (PTV)
(1) PTV_Primary
(2) PTV_Lymph node (PTV_LN)
CTV_LN + 1 isotropic margin.
(3) PTV_Total
PTV_Primary + PTV_LN
Both images (with full bladder & empty bladder) are reviewed for
tumor delineation to ensure that in all possible circumstances PTV
includes maximum extension of the full bladder.

• Organ motion is the dominant source of error
• Magnitude of error depends on region of bladder
being treated.
• Some institute prefer Isotropic 2-cm margins around
bladder (first phase of treatment) or tumor (boost)
• Studies have shown that greatest degree of bladder
wall positional change occurred in cranial direction,
with least variation in anteroinferior direction, limited
by pubic symphysis.
Controversy regarding PTV margin

• Few authors recommended anisotropic margin widths of 1.6
cm anteriorly & posteriorly, 1.4 cm laterally, 3 cm superiorly,
1.4 cm inferiorly.
• The problem is that these margins incorporate much normal
tissue.
• Image-guided radiation therapy with Cone beam CT (CBCT)
is way to reduce these margins significantly
• Correction for errors detected on CBCT is practically
achieved by Foley's catheter. Most of variation is due to
bladder filling, so we catheterize patient & change bladder
status to that at simulation by draining/filling it up as
necessary.

IMRT. Target
delineation
CTV3 64.5 Gy (red ),
PTV1 51 Gy (blue ),
PTV2 54 Gy (orange )
in a patient with
muscle-invasive
bladder cancer with
focus at primary site.
GTV based on MRI
and CT imaging.

1- At least 95 % of the volume of each PTV should receive 100 % of
prescribed dose. Generally, a minimum dose of 95 % and a max dose of
115 % is set for PTV 3.
2- Several critical normal structures surround bladder & therefore need to
be outlined for dose constraints including anorectum, femoral heads,
and bowel.

CTV_Lymph nodes
(CTV_LN)
Contouring

1999http://pubs.rsna.org/doi/
pdf/10.1148/radiology.21
1.3.r99jn40815

2005https://linkinghub.elsevier.c
om/retrieve/pii/S0360-
3016(05)00577-8

Common Iliac Lymph Nodes
Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Sacrum
Psoas muscles
Mesocolon
Common iliac bifurcation
Aortic bifurcation

External Iliac Lymph Nodes
Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Common iliac bifurcation (L5–S1)
Femoral ring (disappearance of lateral muscles of
abdominal wall, artery becomes lateral)
Fat of small bowel, deferent duct or round ligament
Cranial: psoas, int iliac vein, iliac bone, sacroiliac joint
Caudal: piriformis muscle, internal obturator muscle.
Cranial: ext iliac vessels
Caudal: pubic bone (superior branch)
Mesocolon, uterus, bladder
Medial:

Obturator Lymph Nodes
Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Cranial sections of the obturator muscle
Superior margin inferior branch of pubic
bone
External iliac vein
Cranial: acetabulum
Caudal: internal obturator muscle
Internal obturator muscle
Medial:
Bladder

Internal Lymph Nodes
Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Medial:
Common iliac bifurcation (L5–S1)
Cranial sections of coccygeal muscle
Bladder, uterus
Cranial: psoas muscle, int iliac vein, iliac bone, sacroiliac joint
Caudal: piriformis muscle, int obturator muscle
Cranial: sacral wing
Caudal: piriformis muscle
Mesocolon, uterus, bladder

Presacral Lymph Nodes
Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Medial:
Aortic bifurcation
Coccygeal bone superior edge
Posterior rectum wall
Piriformis muscle.
Sacrum
Not applicable

2005http://www.redjournal.org/
article/S0360-
3016(05)01734-7/fulltext

2.0-cm expansion around the distal
2.5 cm of common iliac vessels superior to
bifurcation

2.0-cm expansion around ext iliac vessels
for 9 cm from common iliac bifurcation

2.0-cm expansion around int iliac vessels
for 8.5 cm extending from common iliac
bifurcation

2007https://linkinghub.elsevier.co
m/retrieve/pii/S0936-
6555(07)00642-5

7 mm around common iliac vessels,
extending posterior and lateral borders to
psoas and vertebral body

7 mm around ext iliac vessels, extending
anterior border by additional 10 mm
anterolaterally along the iliopsoas muscle
to include lateral external iliac nodes

18-mm-wide strip along pelvic sidewall
joining external and internal iliac regions

7-mm margin around int iliac
vessels, extending lateral borders to pelvic
sidewall
The upper pre-sacral
region was covered
with a 10 mm strip
over anterior sacral
prominence; where the
margin passed over
muscle or bone, these
structures were deleted
from the CTV

Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Body of L5
Psoas muscles
Loose cellular tissue anterior to common iliac vessels
Bifurcation of common iliac vessels (at inferior border of
L5, at level of superior border of ala of sacrum)
Bifurcation of abdominal aorta (at inferior border of L4)
Medial:
Loose cellular tissue

Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Bifurcation of common iliac vessels (at inferior border of L5)
Femoral artery
Iliopsoas muscle
Anterior border of internal iliac lymph nodes and loose
cellular tissue
Medial:

Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Plane through acetabulum
Superior border of neck of femurs, at the small ischial
foramen
Internal obturator muscle (intrapelvic portion)
Medial:

Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Medial:
Bifurcation of common iliac vessels (at inferior border of L5)
Plane through superior border of head of femurs at level of
superior border of coccyx
Posterior border of external iliac lymph nodes and loose cellular tissue
Piriformis muscle

Cranial:
Caudal:
Anterior:
Lateral:
Posterior:
Medial:
Intervertebral space of L5–S1 (sacral promontory)
Superior border of 1st coccygeal vertebra
Piriformis muscle.
Anterior aspect of sacrum
Not applicable

Common Iliac Lymph nodes
Upper: 7mm below L4/L5
interspace
Lower: level of bifurcation of
common iliac arteries into external &
internal iliac arteries.
CTV should be defined initially by
adding 7 mm margin around
common iliac vessels seen on axial
CT slice.
CTV should also include minimum of
1.5 cm of soft tissue anterior to
vertebral body at midline.
CTV should be modified to exclude
vertebral body, psoas muscle,
& bowel.

Presacral lymph nodes
Lymph node region anterior to S1 &
S2 region
CTV should not be split, & at
midline 1.5 cm margin between
anterior border of CTV & anterior
border of vertebral body or sacrum
should be maintained.
CTV should not be extended into
sacral foramina
Presacral lymph node
coverage should discontinue when
piriformis muscle is clearly
visualized (approximately
the inferior border of S2)

External iliac lymph nodes
Upper: level of bifurcation of
common iliac artery into
external artery
Lower: level of superior aspect
of femoral head where it
becomes femoral artery
7 mm margin around internal
external iliac vessels
should be maintained,
excluding bone, bowel, or
muscle.

Internal iliac lymph nodes
internal artery
7 mm margin around internal
iliac vessels should be
maintained, excluding bone,
bowel, or muscle.
CTV should be disconnected
into two volumes below S2.
CTV should be bounded
posteriorly by piriformis muscle,
CTV extends more than 7 mm
beyond visible vasculature.

Common Iliac Lymph nodes
Upper: L5/S1 interspace
(level of distal common iliac
&proximal presacral lymph
nodes)
Lower: level of bifurcation of
common iliac arteries into
external & internal iliac
arteries.

Presacral lymph nodes
S1 through S3, posterior border
being anterior sacrum &
anterior border approximately
10 mm anterior to anterior
sacral bone carving out bowel,
bladder, bone

External iliac lymph nodes
external artery.
Lower: at top of femoral heads
(boney landmark for Ing.
ligament).
7-mm margin around iliac
vessels connecting external &
internal iliac contours on each
slice, carving out bowel,
bladder, bone.

Obturator lymph nodes
Upper: at top of femoral heads
(boney landmark for Ing.
ligament).
Lower: at top of symphsis
pubis.

Internal iliac lymph nodes
internal artery.
7-mm margin around iliac
vessels connecting external &
internal iliac contours on each
slice, carving out bowel,
bladder, bone.

2012https://linkinghub.elsevie
r.com/retrieve/pii/S0360-
3016(12)00310-0

7 mm around common iliac vessels, with
superior border at 7 mm below L4–L5
interspace

7 mm around ext iliac vessels, terminating
at the level of the femoral head

7 mm around int iliac vessels

2012https://linkinghub.elsevi
er.com/retrieve/pii/S036
0-3016(11)03762-X

The draining lymphatics are associated with the external iliac vessels.
Cranial:
Bifurcation of the common iliac artery into external & internal iliac arteries
Caudal:
Level where external iliac vessels are still located within bony pelvis before
continuing as femoral artery. This transition usually occurs between
acetabulum’s roof & superior pubic rami
Lateral:
Iliopsoas muscle
Medial:
Bladder otherwise a 7-mm margin around vessels.
Anterior:
7-mm margin anterior to external iliac vessels
Posterior:
Internal iliac lymph node group.

These nodes lie along obturator artery, a branch of internal iliac artery that usually
starts at the level of the acetabulum. This branch travels inferiorly and anteriorly,
exiting pelvis via obturator canal. The target volume for the obturator nodes is
small, being 3- to 5-mm in cranio-caudal axis
Cranial:
Three to 5 mm cranial to obturator canal where obturator artery is visible.
Caudal:
Obturator canal, where obturator artery has exited pelvis.
Anterior:
Anterior extent of obturator internus muscle.
Posterior:
Internal iliac lymph node group.
Lateral:
Obturator internus muscle.
Medial:
Bladder.

This group of nodes lies lateral to mesorectum & presacral space & are associated
with internal iliac vessels.
Cranial:
Bifurcation of common iliac artery into external &internal iliac arteries (usually
corresponds to L5-S1 interspace level)
Caudal:
This volume typically ends caudally where fibers of levator ani insert into
obturator fascia & obturator internus, & can be demarcated either at level of
obturator canal, or at level where there is no space between obturator internus
muscle and the midline organs (bladder, SV)
Lateral:
Medial edge of obturator internus muscle (or bone where the obturator internus
is not present) in lower pelvis; iliopsoas muscle in upper pelvis
Medial:
Mesorectum & presacral space in lower pelvis, in upper pelvis, 7-mm medial
margin is recommended from internal iliac vessels
Anterior:
Obturator internus muscle or bone in lower pelvis. in upper pelvis, 7-mm margin
around internal iliac vessels

Presacral space lies posterior to mesorectum
Cranial:
Sacral promontory, defined at the L5-S1.
Caudal:
Inferior edge of the coccyx
Lateral:
Sacro-iliac joints
Anterior:
10 mm anterior to anterior sacral border
encompassing any lymph nodes or presacral vessels
Posterior:
Position at anterior border of sacral
bone. The sacral hollows should be included in this
volume

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Radiotherapy for bladder cancer part ii