This case report describes the implementation of craniospinal irradiation with a posterior fossa boost using intensity-modulated radiation therapy (IMRT) for a 34-year-old male patient with malignant hemangioblastoma. A treatment plan was designed to deliver 50.4 Gy over 28 fractions to the craniospinal axis and posterior fossa. A three-isocenter overlapping junction field technique was used with IMRT to improve dose conformity. Plan quality assurance showed adequate target coverage and organ at risk sparing within limits. IMRT can improve local tumor control for craniospinal irradiation.

1. IMPLEMENTATION OF CRANIOSPINAL IRRADIATION
WITH POSTERIOR FOSSA BOOST USING IMRT:
A CASE REPORT
Victor EKPO
Medical Physicist
November 2022

2. Clinical Presentation
A 34 year old male presented with a diagnosis of
malignant hemangioblastoma. Pt. has inability to
walk, power lower limb 0/5, power upper limb 3/5,
weakness in right side, urinary and fecal continence.
He first had weakness of the limbs twelve (12) years
ago. Pt has had paraparesis since April 2019 and has
been operated twice already (2010/2019) for
cerebellar hemangioblastoma - brain and spine. MRI
and CT conducted prior to radiotherapy, shows
thickening of cervicothoracic segment of the spinal
cord with metastatic infiltration.
2

3. Disease
● Malignant hemangioblastoma is a CNS
tumour, treatable with surgical excision and
radiotherapy.
● Hemangioblastoma is considered the most
common posterior fossa primary brain tumor
in adults, typically young and middle-aged
adults. 3

4. Common Symptoms
● Headache
● Hydrocephalus and symptoms of raised
intracranial pressure
● Cerebellar dysfunction
● Altered mental state
● Polycythemia due to erythropoietin
production.
4

5. TREATMENT
● Pt. to receive 50.4 Gy/28# in two phases
● Phase 1: Craniospinal irradiation
39.6 Gy/22#
● Phase 2: Posterior Fossa
10.8Gy/6#
5

6. RT OPTIONS
3D-CRT
- Two or three fields
- Low dose
conformity
- Difficulty with OAR
constraints
- Difficulty with
junctions between
fields
VMAT
- Advanced
technique
- Difficulty with
field size
- May require
gaps between
fields.
IMRT
- Advanced
technique
- Can use three
isocentres
- Two possible
techniques (TIJJ
or TIOJ)
6

7. CRANIOSPINAL IRRADIATION (CSI)
● CSI is often adopted for children with
medulloblastoma and other malignancies. It is
accompanied with a long field.
● Implementation of CSI for adults has the added
challenge of a much larger field (field length >
54cm), increasing the complexity of planning
and patient specific quality assurance (PSQA).
7

8. TIJJ vs TIOJ
● TIJJ is Three-Isocentre Jagged Junction.
For this, the field edges have to be manually set,
and staggered in 1.1 cm steps.
● TIOJ uses Three-Isocentre Overlap-Junction
Fields edges overlap with 5-15 cm overlap.
Inverse treatment planning with IMRT reduces
the complexity for matching fields. 8

9. Our TIOJ IMRT plan
● Entire field length (cranium to lumbar s.) – 59.8cm
● 3 isocentres – 1 for cranium, 2 for spine.
● The isocentres are spaced equidistant to each other
(18.6 cm) and overlap.
● Isocentres are selected in sagittal plane, to be within
treatment fields, on the same lateral and
anterioposterior-position.
9

10. Our TIOJ IMRT plan
● 11 beams were optimized simultaneously.
● 5 cranial beams - 0°, 40°, 95°, 265°, and 320°
● 3 upper spine - 145°, 180°, and 215°
● 3 lower spine - 145°, 180°, and 215°
● Collimator angle - 0°
● No couch rotation 10

11. 11
Interest points are equidistant (18.6 cm).
Isocentres are selected such that they are on the same anteriorposterior and lateral
planes. Requiring only longitudinal movement of couch between fields.

12. 12

13. 13
CSI PLAN ONLY

14. 14
CSI + POSTERIOR FOSSA PLAN (pg1/3)

15. 15
CSI + POSTERIOR FOSSA PLAN (pg2/3)

16. 16
CSI + POSTERIOR FOSSA PLAN (pg3/3)

17. PATIENT-SPECIFIC QA (PSQA)
PSQA was implemented with PTW Octavius 4D for each isocentre.
17

18. CONCLUSION
● Use of IMRT technique showed adequate coverage of PTVs
(V95% Gy > 99% of volume) and minimal hotspot (V105% Gy < 2%).
● Dose to Spinal cord < 45 Gy; Dose to brainstem < 54 Gy.
● Sparing of cochlear (mean dose<45Gy), lens (max dose<7 Gy)
with other organs at risk (OARs) within limits.
● Treatment for fields for CSI was given simultaneously.
● Special care must be taken to move couch between fields by
measured distance when treating.
● Use of IMRT for CSI has been shown to improve local control of
tumour1.
18

19. Thanks!
Any questions?
You can find me at
about.me/overjoy
19
Case report was first presented at an oncology clinical audit meeting with
oncologists, medical physicists, radiotherapists and oncology nurses.
Plan was implemented using Elekta MONACO TPS v5.11 with MOSAIQ OIS.

20. References
1Paulino A, Mazloom A, Teh B, et al. Local Control After Craniospinal Irradiation, Intensity-
Modulated Radiotherapy Boost, and Chemotherapy in Childhood Medulloblastoma. Cancer
2011;117:635–41. VC 2010 American Cancer Society.
2Wang Z, Jiang W, et al. A simple approach of three-isocenter IMRT planning for craniospinal
irradiation. Radiation Oncology 2013 8:217. doi:10.1186/1748-717X-8-217.
3Lee Y, Kim A, et al. Practical Dose Delivery Verification of Craniospinal IMRT. J Appl Clin Med Phys.
2015 Nov; 16(6): 76-83 PMID:26699557. doi:10.1120/jacmp.v16i6.5481
4Prabhu RS, Dhakal R, Piantino M, Bahar N, Meaders KS, Fasola CE, Ward MC, Heinzerling JH,
Sumrall AL, Burri SH. Volumetric Modulated Arc Therapy (VMAT) Craniospinal Irradiation (CSI) for
Children and Adults: A Practical Guide for Implementation. Pract Radiat Oncol. 2022 Mar-
Apr;12(2):e101-e109. doi: 10.1016/j.prro.2021.11.005. Epub 2021 Nov 28. PMID: 34848379.
Nanos CA, Abatzoglou I, Koukourakis MI. Volumetric modulated arc therapy (VMAT) craniospinal
imageguided radiotherapy and chemotherapy for high-risk medulloblastoma in adults: A case
report with analysis of the technique. J Case Rep Images Oncology 2021;7:100087Z10CN2021.
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