This document discusses radiotherapy planning and treatment for esophageal cancers. It covers definitive, neoadjuvant, postoperative and palliative radiotherapy doses and techniques. It describes the evolution from 2D to 3D conformal planning, including target delineation using PET-CT, and considerations for organ at risk doses. Intensity modulated radiation therapy (IMRT) is discussed as an advanced technique that allows improved sparing of normal tissues while maintaining tumor dose.

1. Radiotherapy
Planning for
Esophageal Cancers
Parag Sanghvi, MD, MSPH
9/12/07
Esophageal Cancer Tumor Board
Part 1

2. Radiation for Esophageal Cancers
 Definitive
 Cervical Esophagus – 60 – 66 Gy
 Thoracic/GE junction – 50 -54 Gy
 Dose escalation has not shown improved survival in
definitive CRT for esophageal cancers (INT 0123)
 Neoadjuvant
 T3 or higher
 N+
 45 – 50 Gy

3. Radiation for Esophageal Cancers
 Post – Operative
 Rare; difficult to tolerate
 45 Gy
 Palliative
 Dysphagia
 30 – 35 Gy

4. Treatment Planning
 Simulation
 Immobilization
 Vac Lok
 Isocenter set-up
 2D vs. 3D
 3D – Treatment planning CT
 Tattoos
 Daily Set-up

5. Treatment Planning
2D Era – RTOG 8501
 RTOG 8501 compared CRT (50 Gy) to RT alone (64Gy)
 Mid/Lower Esophageal Cancers
 Initial Field was AP/PA to 30 Gy in CMT arm
 Extended from SCV region to GE junction
 Omitted SCV nodes in lower esophageal tumors
 Boost field was tumor + 5 cm sup/inf with a 3 field or opposed
obliques
 Advantages
 AP/PA limited lung dose
 Replacing PA with oblique fields limited spinal cord dose
 Disadvantages
 For distal tumors, significant cardiac volume
 Entire extent of the esophagus treated

6. Treatment Planning – 3D Era
 Target Delineation
 PET-CT fusion
 EUS findings
 Definitions
 GTV – Gross Tumor Volume ( Tumor + grossly enlarged
LN)
 CTV – Clinical Target Volume – Includes microscopic
disease
 PTV – Planning Target Volume – accounts for setup error
and intra-fraction motion

7. Margins / Normal Tissue Tolerances
 Margins / PTV definitions
 Superior / Inferior – GTV + 5 cm
 Lateral – GTV + 2 cm
 Normal Tissue Tolerances – Organs @ Risk
(OAR)
 Cord - max dose 45 -50 Gy
 Lung V 20 Gy - 20 -30%
 Liver V 30 Gy – 23- 30%
 Kidney
 Heart

8. Radiation Toxicities
 Esophagitis
 Esophageal Stricture
 Radiation Pneumonitis
 V20 Gy < 20-40%; V30 Gy < 18%; Mean Lung
Dose <20 Gy
 Post-operative Pulmonary complications
 MDACC study showed that the amount of Lung
that is spared from 5 Gy of radiation predictive

9. Radiation Toxicities
 Pericarditis
 Cardiovascular disease
 V40 Gy < 30%
 Radiation Nephropathy
 Limit dose to atleast 2/3 of 1 Kidney

10. Treatment Planning
 3D Treatment Planning (CT- based)
 Start AP/PA
 Treat to cord tolerance
 39.6 – 41.4 Gy
 Then off-cord
 2 field or 3 field
 AP/RAO/LAO for cervical/upper thoracic lesions
 AP/RPO/LPO for lower lesions
 RAO/LPO for distal esophagus lesions
 Treat to total 50.4 – 54 Gy

11. Treatment Planning - Evaluation
 Dose Volume Histograms
 CT data allows to quantify dose received by
tumor as well as organs at risk

12. 3D Planning

13. 3D Planning

14. 3D Planning

15. 3D Planning

16. 3D Planning

17. 3D Planning

18. 3D Planning

19. 3D Planning - DVH

20. IMRT
 Intensity Modulated Radiation Therapy
 Clinical Rationale
 Tumors arise from/within normal tissues
 Normal tissues often limit the radiation doses that can be
safely prescribed and delivered
 Organs at risk in close proximity may have limited radiation
tolerance
 IMRT allows for the reduction of radiation dose delivered
to normal tissue
 Ability to maintain a high dose to the tumor

21. IMRT - Benefits
 Normal Tissue sparing
 Reduced late toxicities
 Dose escalation
 Dose painting
 Ability to increase dose to areas of higher tumor burden
 Re-irradiation

22. IMRT - Basics
 Ability to break a large treatment port into multiple
smaller subsets (field segments or pencil beams)
 Through utilization of MLCs or other intensity modulation
technology
 A computer system to enable such field fragmentation
 Computer system capable of performing inverse
treatment planning
 Defining the problem/solution upfront in numeric format

23. IMRT - Basics
 Multiple static non-coplanar radiation fields
 Each field has a unique radiation intensity profile
 The fluency of radiation is altered during the delivery of the radiation field
 Multileaf collimator
 Planning CT scan (can be “fused” to an MRI or PET scan)
 The tumor/volumes and critical structures are drawn
 Prescription dose and dose constraints are programmed into the
radiation-planning software for generation of the radiation plan

24. Requirements for IMRT
 LINAC
 Beam modulation device
 MLC (multi-leaf collimator)
 MlMiC (Peacock system)
 Compensators
 (Inverse) treatment planning software
 QA program