This is a made easy summary of ICRU 89 guidelines for gynecological brachytherapy. Extra practical questions for MD/DNB Radiotherapy exams are also attached.

1. 1
ICRU 89 Recommendations & Beyond
A Short Summary by Dr. Abhishek Basu Jr. (Tutor, MCH, Kolkata)
Level 1: Minimum standard for reporting
FIGO/TNM stage
Tumor assessment is always based on initial and repeat clinical gynecologic examination and
on additional volumetric or sectional imaging (MRI, CT, US, PET CT) as available.
Initial and residual GTV:
GTVinit before any treatment
GTVres at brachytherapy
Schematic 3D documentation on a clinical diagram of the findings on initial and repeat
clinical gynecologic examination (transverse, mid-sagittal, mid-coronal sections; speculum
view): location of GTVinit and GTVres plus residual pathologic tissue dimensions of GTVinit
and GTVres plus residual pathologic tissue.
Maximum width and thickness, height as available (in mm) related to the endo-cervical canal
(left, right, anterior, posterior) related to the upper vagina (fornices) (height) as appropriate
configuration of GTVinit and GTVres plus residual pathologic tissue spread and growth
pattern of GTVinit ( exophytic /infiltrative).
High-risk CTV
CTVHR : GTVres at the time of brachytherapy (after response to chemo-radiotherapy) + any
pathologic residual tissue (CTVIR in the case of prescription to CTVIR) and the whole cervix
Schematic 3D documentation on a clinical diagram for clinical gynaecologic examination
(transverse, mid-sagittal, mid-coronal sections; speculum view):
o location of CTVHR
o dimensions of CTVHR
o maximum width and thickness, height as available (in mm)/ standard height
o related to the endo-cervical canal (left, right, anterior, posterior)
o related to the upper vagina (fornices) (height) as appropriate configuration of CTVHR
o volume is calculated by ellipsoid formula (optional) except for
o extensive vaginal involvement.

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Dose reporting:
• TRAK
• Point A dose
• Recto-vaginal reference-point dose
• D 0.1cm3 and D2cm3 for the bladder and rectum
Dose delivery pattern:
• Absorbed-dose rate/dose per fraction
• Number of fractions
• Time between fractions
• (Pulse number, size, time, if PDR)
• Overall treatment time
• Total EQD2 dose
Source and dose calculation:
• Radionuclide and source model
• Source strength
• Dose-calculation algorithm - (AAPM TG 43)

3. 3
Level 2 Reporting ( Advanced ) : Level 1 + the following
Volumetric imaging-based management Radiography/treatment plan-based Management
Volumetric-imaging approximation based on:
3D delineation of volumes (on volumetric images
with applicator):
GTVres
CTVHR
(CTVIR if used for prescription)
With maximum width, height, thickness, and with
volume
Dose reporting for defined volumes:
D98 %, D90 %, D50 % for the CTVHR
(D98 %, D90 % for the CTVIR if used for
prescription)
D98 % for GTVres & for pathological lymph nodes
Dose reporting OARs:
Bladder reference point dose
D0. 1cm3 , D2cm3 for sigmoid
D 2cm3 bowel
Intermediate- and low-dose parameters in bladder,
rectum, sigmoid, bowel
(e.g.,V15 Gy, V25 Gy, V35 Gy, V45 Gy or D98 %,
D50 %, D2 %)
Vaginal point doses at level of sources (lateral at 5
mm)
Lower- and mid-vagina doses (PIBS, PIBS+2 cm)
PIBS = post inf border of symphysis
Radiographic approximation based on:
Topography for volumes (on isodose plan with
applicator/on radiographs with applicator)
Similar
Dose reporting for defined volumes:
Estimated dose to CTVHR
(according to estimated maximum width and
thickness)
Pelvic wall point (optional)
Lymphatic trapezoid (optional)
Dose reporting OARs:
Vaginal point doses at level of sources (lateral at 5
mm)
Lower- and mid-vagina doses (PIBS, PIBS+2 cm)
Level 3: Research-oriented reporting
All that is reported in Level 1 and 2 plus:
Volumetric imaging approximation based on:
GTV, HR CTV: Functional imaging for additional information at diagnosis,
during treatment, and at brachytherapy;
PTV
Margins along the tandem.
Isodose surface volumes:
For example
85 Gy EQD2 volume

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60 Gy EQD2 volume
OAR volumes and points:
(1) Additional bladder and rectum reference points
(2) OAR sub-volumes (e.g., trigonum or bladder neck, sphincter muscles)
(3) Vagina (upper, middle, lower)
(4) Anal canal (sphincter)
(5) Vulva (labia, clitoris)
(6) Other volumes/sub-volumes of interest (e.g., ureter)
Dose–volume reporting for OAR:
(1) Dose–volume and dose–surface histogram parameters for additional
OARs and sub-volumes
(2) Vaginal dose profiles, dose–volume, and dose–surface histograms
(3) Length of treated vagina
Key points of ICRU 89 – What makes it Unique ?
Five Points Someone ….
1. DEFINITIONS OF VOLUMES & ADAPTIVE BRACHYTHERAPY
Adaptive CTV-T (CTV-Tadapt) can be defined after any treatment phase and includes in
any case the GTV-Tres and the residual surrounding pathologic tissue, if present. The
adaptive CTV-T is a sub-volume of the initial CTV-T, except in the case of tumor
progression.
High-Risk CTV-T (HR – CTV ) is defined as a specific form of the adaptive CTV-T for
“cervix cancer radiotherapy” following the GEC ESTRO recommendations. CTV-THR
includes the GTV-Tres and the whole cervix and adjacent residual pathologic tissue, if
present. It is the volume bearing the highest risk for recurrence. The CTV-THR for cervix
cancer is selected by clinical examination and imaging at the time of brachytherapy, after 40
Gy to 45 Gy EBRT plus chemotherapy in advanced cervical cancer.
Residual GTV-T (GTV-Tres) is defined as the residual macroscopic tumor at the time of
(brachytherapy) boost after treatment assumed sufficient to control microscopic disease.
GTV-Tres still bears clinical and/or imaging characteristics similar to the initial GTV-Tinit
and may represent macroscopic and/or microscopic and/or even no residual disease.
Residual pathologic tissue may surround the residual GTV-T and bears different clinical
and/or imaging characteristics (e.g., edema, fibrosis) compared with the initial GTV-T. It is
always located within the region of the initial GTV-T.
In the context of adaptive radiotherapy, the initial GTV-T ( Disease at diagnosis ) is
denoted as GTV-Tinit.

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Intermediate-risk CTV-T (IR- CTV) represents the area of the GTVinit as superimposed
on the topography at the time of brachytherapy and a margin surrounding the anatomical
cervix borders (CTV-THR) in areas without an initial GTV. The CTV-TIR therefore
always includes the CTV-THR and margins as appropriate.
The GEC ESTRO Recommendations suggest a 10 mm margin in the lateral and cranio-
caudal directions and 5 mm in the anterior–posterior direction.
The terms “initial CTV-THR/initial CTV-TIR” may be also used for CTV-T1/CTV-T2 as
defined at diagnosis.
Low-risk CTV-T ( LR -CTV ) represents compartmental areas at risk for potential
contiguous or incontiguous microscopic spread from the primary tumor (identical to CTV-
T3). CTV-TLR comprises in advanced cervix cancer the whole parametria, the whole uterus,
the upper part of the vagina, and the anterior/posterior spaces toward the bladder and rectum.
Remarks : More or less Continuation of GEC ESTRO Guidelines
2. Need of a PTV ??
“Internal target motion” of the CTV-HR in relation to the applicator can be regarded as
minimal, if the applicator is fixed (e.g., by an intravaginal tamponade). However, “geometric
uncertainties” may occur, in particular in the longitudinal direction along the tandem. As
margins along the longitudinal axis of the tandem have very limited impact on the dose
throughout the target, “longitudinal margins” along the axis of the tandem maybe used to
some degree to compensate for these set-up variations, even after application (e.g. ILRT).

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Addition of margins orthogonal to the tandem axis leads to a dose increase throughout the
entire target and are therefore not recommended.
Dose profiles comparing the effects of adding margins on dose distribution in the CTVand
PTV in external beam therapy (left panel) and in intracavitary cervical cancer brachytherapy
(right panel). In external beam radiotherapy, adding a PTV margin increases the volume
irradiated to a high dose, but the magnitude of the CTV dose remains roughly unchanged. In
contrast, application of a PTV margin in the lateral and anterior–posterior directions in
brachytherapy and a re-normalization of dose to the PTV will result in a systematic increase
of the dose throughout the CTVand organs at risk.
3. WHAT ABOUT THE OARs ?
Volumetric reporting of OARs. Small absolute volumes (e.g., 2 cm3, 0.1 cm3) correspond to
typical brachytherapy-related morbidity, such as teleangiectasia and ulceration/fistula. These
volumes can have different locations in the OARs depending on the application technique .
Vagina reference points (on radiographs):
Upper-vagina points : (5 mm lateral from vaginal applicator surface, right and left) for
brachytherapy-related morbidity.
Anatomical points for lower and mid vagina
(PIBS, PIBS+2 cm) : PIBS = Post inf border of the symphysis pubis.
The vaginal reference length (VRL) (PIBS to midpoint between the vaginal sources) can
serve as an indicator to assess the varying position of the vaginal sources relative to the
surrounding normal-tissue structures.
In case of IMRT , Brachy Reporting also includes RVR ( Remaining vol at risk )
The volume that is within the imaged region of the patient, but outside all delineated OARs
and CTVs should be identified as the “remaining volume” at risk (RVR).
Point to be noted that Both VRL & RVR are level 3 dose reporting of OAR, ie, optional.

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4. CONCEPT OF EQD2 Because of historical precedents and clinical experience EQD2
referring to photon doses of 2 Gy/fraction is commonly used. For protocols involving
different radiations, assumed values of β are required for both radiation types and must be
specified. This ICRU/GEC-ESTRO report recommends the use of the equieffective
formalism, particularly EQD2, for addition of absorbed doses to report doses for planning
aims, prescriptions, and doses delivered.
5. Speciality of Dose Reporting
The GEC ESTRO report recommended the reporting of D100 % and D90 %, defining the
minimum doses delivered to 100 % and 90 % of the target volume, respectively.
These DVH parameters reflect the dose in the outer region of the target. D90 % is more
stable with respect to random uncertainties when compared with an absolute minimum target
dose, D100 %.
A more robust metric is the near-minimum dose D98 %, in which 2 % of the target volume
receives less than this dose. D98 % is also proposed for IMRT treatments in ICRU Report 83
The use of D98 % and D90 % parameters is recommended for reporting dose to the CTVHR.
D50 % is also used in reporting CTV HR & OAR. BUT …..
For IMRT treatment plans, the D98 % and D2 % are usually between +10 % of D50%.
The situation is different for intracavitary brachytherapy combined with EBRT. The
difference depends in particular on the tumor size and the implant, as well as on the
weighting of EBRT and brachytherapy doses. For conventional treatment
schedules in which about half of the total EQD2 to the primary target is
delivered by brachytherapy, the dose heterogeneity is significant with D50 %, in
terms of total EQD2, being substantially higher than D90 % .
CONCLUSION – NOT THAT SIMPLE BUT STILL ICRU 89 IS AN
AMULGAMATION OF ICRU 38 + GEC ESTRO GUIDELINES WITH FEW
ADAPTATIONS FROM ICRU 83 AS WELL.
Extra questions
1. Total equieffective dose (EQD2) calculated according to the linear-quadratic model
through the following steps: ( EBRT + Brachy dose )
(1) Brachytherapy EQD2 for each fraction
(2) Total brachytherapy EQD2
(3) Total EBRT EQD2
(4) Accumulated total EBRT + brachytherapy EQD2
Practical tip : Use ABS excel spread sheet available at ABS website .

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2. What is TRAK & it’s importance in brachytherapy ?
Historically, the strength of radium sources was specified in terms of the mass
of radium (units of mg) contained in the source. When artificial radionuclides became
available as radium substitutes for use in brachytherapy, most manufacturers specified the
sources in “milligram radium equivalent” in order to simplify the use of the sources as
radium substitutes. Then comes RAKR for source strength specification of radionuclides.
a) The total reference air kerma (TRAK) is the integral of the RAKR over the treatment
duration, summed for all sources, without regard to the geometry of the application.
The TRAK is a purely physical quantity & as because biological effect varies with
absorbed dose, absorbed-dose rate, and tissue type, there can be no direct relationship
between TRAK and biological effect.
b) The absorbed dose in any organ and the integral dose in the patient are directly
proportional to the TRAK, with approximately the same relationship for most of the
high-energy-photon-emitting radionuclides used in cervical brachytherapy.
c) The inverse-square law applied to the TRAK allows an estimation of the absorbed
dose during treatment at distances greater than 15 cm from the centers of the sources
i.e., in the pelvis and abdomen for cervical brachytherapy.
d) A simple relationship does not exist between TRAK and the absorbed dose near the
sources, i.e., in the gross tumor volume and the CTV or to points such as Point A.
Similarly, the TRAK does not allow the shape of the treated volume to be derived.
However, it has been shown that the volume contained within a given isodose surface
can be estimated from the TRAK , this is because both the volume contained within
an isodose surface and TRAK reflect the integral absorbed dose, but the shape of the
isodose surface depends on the geometric distributions of the sources over time.
3. What is clinical drawing ? Clinical drawing is conceptualised for 3 dimensional
documentation of disease based on clinico-radiological assessment.
Height (dh) is measured in sagittal view along the long axis of uterus.
Width (dw) is measured in axial view, represents greatest lateral diameter.
Thickness (dt) is measured in sagittal view, perpendicular to the height.

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4. What is Bladder protocol, any advantage?
The bladder filling protocols vary from emptying with indwelling urinary catheter (ICRU 38
recommendations) to a known limited filling status (e.g., 50 cc) to full bladder. Various
studies have shown that there is no significant impact of bladder filling on bladder dose
volume parameters, although larger bladder filling tend to have higher doses. Small bowel
doses are lesser with higher bladder volumes. Bladder filling has no impact on rectum and
sigmoid doses. The bladder 2 cc volumes do not move significantly with increasing bladder
filling.
5. In ICRU 38 , why the reference volume is covered by 60 Gy isodose line ?
The minimum dose to be given to the tumor is EBRT(40Gy) + Brachytherapy (20Gy) = 60
Gy LDR irrespective of EBRT response. This concept was originated from teachings of
schools of Belgium & Paris and later carried forward to the inception of IRCTV by GEC
ESTRO. At that time a dose of 60 Gy was considered optimum with the dose constraints of
bladder & rectum (Whole organ TD5/5 = 60-65Gy ) keeping in mind.
The 60 Gy reference volume defined in ICRU Report 38 (ICRU, 1985) can currently be
better understood by the relationship of this 60 Gy reference volume to the volume and
location of the tumor imaged at diagnosis, prior to external-beam irradiation. This is similar
to the newly defined Intermediate Risk CTV (CTV IR) using an image-guided adaptive-
brachytherapy approach.
6. Are Paris method & Paris System synonymous?
No, Paris Method is for intracavitary insertion in the era of Stockholm, Paris, Manchester.
Paris System is one of the dedicated ISRT system along with Quimby, Manchester &
Computer system.

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7. What is an Ideal ICRT Application ?
Tandem: Axis of the tandem should be central & it should Bisect the ovoids.
Midway between bladder & S1-S2.
1/3rd
of the way between S1-S2 & Symphysis pubis.
Ovoids: Largest (inverse Sq law : ↑size > ↓vaginal mucosal dose), against the cervix &
should be separated by 0.5-1cm.
There should be adequate packing to keep away bladder & rectum from the implant.
This is just a continuation of Fletcher modifications of Manchester system, where it was
advised to keep the tandem in mid-plane in the pelvis, equidistant from the sacral promontory
and pubis and the lateral pelvic walls to avoid over-dosage to the bladder, sigmoid, or one
ureter. The tandem was recommended to bisect the colpostats on the AP films and bisect their
height on the lateral films (Fletcher, 1980).
8. What is the relation between Point A & HRCTV dose?
The relation between the absorbed dose at Point A and the CTVHR D90 depends largely on
the CTVHR volume . For small tumors, the Point A absorbed dose is lower than the D90 %,
whereas for large tumors, the Point A absorbed dose is higher than the CTVHR D90 %.
The CTVHR D90 % typically varies between 60 % and 150 % of the Point-A absorbed
dose.
The situation on the left shows a maximum width limited to 4 cm, with 2 cm left and 2 cm
right. Therefore, the Point A dose is representative of the dose covering the entire CTVHR.
The situation on the right shows a maximum width of 6.5 cm, with 2.5 cm left and 4 cm right.
The minimum dose for such a tumor is substantially lower, approximately 80 % on the left
and 43 % on the right.With 84 Gy prescribed to Point A (45 Gy EBRT + 4 ×7 Gy

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brachytherapy), the dose decreases to 57 Gy EQD2 on the right side of the CTVHR and to 78
Gy EQD2 on the left side.
9. How ISRT planning is done ?
▪ HRCTV is drawn and dose is prescribed over HRCTV.
▪ When HRCTV is not drawn dose is prescribed arbitrarily at first around the needles,
then geometric optimisation with isodose reshaping is done ( visual simulation ) to
look for the coverage of disease . Disease mapping is done by clinical drawings and
pre BT MRI.
▪ Volumetric / dosimetric optimisation is done by changing dwell position (altering step
size) and dwell time. Step size 2.5 mm. means source will jump and sit after 2.5 mm
step. For a 5cm insertion dwell position is 5/2.5 = 20 positions .Dwell time changes
disease and OAR coverage. Step size change will also change geometry of plan ,
dwell position and time, overall tt time will also change.
10. Details of Radionuclides used in Brachytherapy

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11. What is Point of Chassagne ?
Pelvic wall reference point in the name of Chassagne and Horiot, 1977. Representative
of the absorbed dose at the distal part of the parametrium and at the obturator lymph nodes.
On an AP image, the PWRP is located at the intersection of the horizontal line tangential to
the cephalad-most points of the acetabula and Vertical lines tangential to the inner aspect of
each acetabulum.
On a lateral image, it’s the highest mid distance point between two acetabula.
12. The lymphatic trapezoid of Fletcher
▪ A line is drawn from the junction of vertebral bodies S1–S2 to the top of the
symphysis. Then a line is drawn from the middle of that line to the middle of the
anterior aspect of vertebral body L4. This line identifies the coronal plane containing
the trapezoid.
▪ A trapezoid is constructed in the plane defined above and centered on the body axis as
shown on the left with the top 4 cm long, bottom 12 cm long, and the sides connecting
the ends of those two lines.
▪ The absorbed doses at the inferior corners of this figure provide an estimate of the
absorbed-dose rates in the mid-external iliac lymph nodes.
▪ The superior corners of the trapezoid are used to estimate the absorbed dose in the
low para-aortic nodal region.

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▪ The absorbed doses at the midpoint of each side of the trapezoid are used to estimate
the absorbed dose in the low common iliac lymph nodes.
13. Contemporary ICRT / ISBT techniques
Tandem + Ring = Based on Modified Stockholm technique
Ring is available in different diameter 26,30, 34 mm. Acrylic caps over the ring tube
to reduce the dose to the vagina. The ring & intrauterine tube are fixed to each other
with a screw. The ring provides an additional degree of freedom to load the vaginal
sources over the ovoids. However, there are no substantial data to suggest the
dosimetric difference between TO and ring applicator.
Advantage of ring – fixed geometry, customised planning can be done,
interrelationship between the oviods is maintained, beneficial in shallow fornices.
Tandem and Ovoid Techniques = Modified Manchester/ Fletcher Technique.
Tandem with vaginal cylinders – Consists of central tandem and vaginal cylinders
available in various diameter sizes Cylinders are used in cases of narrow conical
vagina where ovoids/ring are difficult to accommodate or in cases of residual disease
extending beyond the upper vagina. The dose distribution is cylindrical. As there is a
single source channel, lateral throw off of dose in to the parametrium is less as
compared to ovoids/ring.

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Tandem + Mould = Previously used for LDR, currently used in PDR & HDR
brachytherapy.
The Henschke tandem and ovoid applicator was initially unshielded (Henschke, 1960; Perez
et al., 1985) but later modified with rectal and bladder shielding. It consists of hemi-
spheroidal ovoids, with the ovoids and tandem fixed together. Sources in the ovoids are
parallel to the sources in the uterine tandem.The Henschke applicator can be easier to insert
into shallow vaginal fornices in comparison to ovoids/colpostats.
The Vienna applicator (Nucletron, Veenendaal, The Netherlands; Varian, Palo Alto, USA)
is a modified ring applicator with holes in the ring for needle guidance parallel to the uterine
tandem and the ring fixed to the cervix through the tandem and vaginal packing.The Vienna
applicator is used for treating parametrial residual disease after radio-chemotherapy with
unfavourable topography . Additional absorbed dose in residual disease can be provided with
the addition of a number of needles implanted in those parts of the lateral tumor extension not
covered by the intracavitary pear-shaped absorbed-dose pattern. Used in combined approach
ICRT+ISRT .

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16. 16
Venezia applicator ( IC + ISRT)
Consists of central tandem, ovoids/two ring halves that can accommodate straight
or diverging interstitial parametrial needles and a detachable perineal template. The
applicator is designed for the treatment of advanced disease with involvement of lateral
parametrium with the modified ovoid/ring 2 halves system and/or lower vagina
or paracolpos with the perineal template

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14. Post EBRT response : Generally tumor regression (GTV volume) occurs in the range of
70-90% at the time of brachytherapy.
If response is more than 70% then its good response, < 70% response = poor response.
15. Role of ultrasound in gynecological brachytherapy?
For brachytherapy, US can be used to ensure optimal positioning of applicators and needles
within the target volume and to assist in detecting and contouring the target volume and OAR
(Petric et al., 2011). Real-time US can be used during insertion of the intrauterine tandem to
achieve optimal placement, for example, in patients with an obliterated endo-cervical canal or
with complex pathology, and to prevent inadvertent uterine perforation. Both trans-rectal and
trans-abdominal US have been used in interstitial treatment to guide the depth of needle
insertion. Post-insertion US can be used to measure the diameter of the cervix, the thickness
of the uterine wall, and the thickness of the vagina at the time of brachytherapy to aid in
absorbed-dose specification.
# Brachytherapy is an endless sea, in this summary only few aspects are addressed which are
learnt from ICRU 89, EMBRACE, IBS Guidelines & various contemporary research articles.
For any query or suggestion, feel free to contact @ dr.abhishekbasu123@gmail.com