Epworth HealthCare

Intensity-Modulated Radiotherapy versus Three-

Dimensional Conformal Radiotherapy; a retrospective

study

Epworth Radiation Oncology

Emma Fitzgerald

Overview

• Literature search into Breast Intensity-Modulated Radiation Therapy (IMRT)

• Challenging Planning Target Volumes (PTV)

• Breast IMRT solution

• Critical review of technique

• Identify the clinical indicators

• Future direction of technique

History

• Radiation Therapy remains integral to the management of Breast Cancer (1-6)

• Dosimetric Improvements from Two-Dimensional to Three-Dimensional Conformal Radiation Therapy (3DCRT)

• Are further improvements possible?

• Does IMRT have a role to play?

• If so, what are the indicators?

Literature – Breast IMRT

• Retrospective studies question feasibility (1-3, 6, 8, 9, 10, 11)

• Increased trend to use IMRT for breast but no

detailed specific clinical scenarios (Lisa, A 2011)

• IMRT is dependent upon technique (2, 6-7, 12)

PositivesPositives NegativesNegatives

Improved HomogeneityImproved Homogeneity ↑ ↑ IIntegral Dosentegral Dose

BetterBetter PTV conformity indexPTV conformity index ↑ Heart↑ Heart MeanMean DoseDose

↓ Ipsilateral Lung V20 Gy↓ Ipsilateral Lung V20 Gy ↑ Contralateral Breast Dose↑ Contralateral Breast Dose

Clinical Example

• Comparison of 2 different IMRT plans 6 FLDs Tan Approach Vs 9 FLDs ~30⁰ apart

Background

• Field-In-Field PTV based approach is standard

• Acknowledge IMRT is resource intensive

• Limited benefit to replace as standard (11)

• However, real role to specific clinical scenarios (7, 9, 13, 10)

– Internal Mammary Chain (IMC)

– Complex volumes close to Organs At Risk (OARs)

PTV & OAR

PTV & OAR

PTV & OAR

Right Coronary Artery (RCA) Planning Risk Volume (PRV)

4.2cm

PTV & OAR

PTV & OAR

• Left Anterior Descending (LAD) Coronary Artery Delineation

The Clinical Decision

• Radiation Oncologist Driven

• Higher concern for IMC recurrence than Chronic toxicity

– LAD dose <30 Gy (14)

– RCA dose <35 Gy

• Application of Evidence Based Dose Constraints (14, 16)

• Extensive IMRT planning and treatment experience

• Collaboration with other sites

Method

• 9 field Beam Arrangement:

Method

• Supraclavicular Fossa (SCF) and Axilla Beam Arrangement:

Method

• SCF/Axilla Beam Arrangement:

Method

• Target Structures for IMRT Optimisation:

Method

• Target Structures for IMRT Optimisation:

Method

• Target Structures for IMRT Optimisation:

Method

• Target Structures for IMRT Optimisation:

Method

• 3DCRT - Wide Field Tangents & SCF/Axilla:

Results

Isodose Range 47.5 Gy IMRT Vs 3DCRT

Results

Isodose Range 47.5 Gy IMRT Vs 3DCRT

Results

Isodose Range 25 Gy IMRT Vs 3DCRT

Results

Isodose Range 5 Gy IMRT Vs 3DCRT

Results

• Dose Volume Comparison – IMRT Vs 3DCRT IMRT (Gy)IMRT (Gy) 3DCRT (Gy)3DCRT (Gy) Goal (Gy)Goal (Gy)

PTV D 98%PTV D 98% 47.047.0 47.8 47.8 4747.5.5

PTV D 2 %PTV D 2 % 52.852.8 54.254.2 53.553.5

Right Lung V20Right Lung V20 30.030.0 46.046.0 < 15% (7.5)< 15% (7.5)

Heart MeanHeart Mean 7.27.2 2.32.3 < 5< 5

Heart MaxHeart Max 39.339.3 46.846.8 < 50< 50

PRV RCA MaxPRV RCA Max 38.538.5 46.546.5 < 35< 35

LADLAD N/AN/A N/AN/A < 30 Max< 30 Max

Brachial PlexusBrachial Plexus 51.1051.10 51.951.9 < 52 Max< 52 Max

Contra Breast MaxContra Breast Max 11.2 11.2 47.247.2 < 5 ***< 5 ***

Contra Lung MeanContra Lung Mean 2.92.9 0.30.3 < 5< 5

Results

• Dose Volume Comparison – IMRT Vs 3DCRT IMRT (Gy)IMRT (Gy) 3DCRT (Gy)3DCRT (Gy) Goal (Gy)Goal (Gy)

PTV D 98%PTV D 98% 47.047.0 47.8 47.8 4747.5.5

PTV D 2 %PTV D 2 % 52.852.8 54.254.2 53.553.5

Right Lung V20Right Lung V20 30.030.0 46.046.0 < 15% (7.5)< 15% (7.5)

Heart MeanHeart Mean 7.27.2 2.32.3 < 5< 5

Heart MaxHeart Max 39.339.3 46.846.8 < 50< 50

PRV RCA MaxPRV RCA Max 38.538.5 46.546.5 < 35< 35

LADLAD N/AN/A N/AN/A < 30 Max< 30 Max

Brachial PlexusBrachial Plexus 51.1051.10 51.951.9 < 52 Max< 52 Max

Contra Breast MaxContra Breast Max 11.2 11.2 47.247.2 < 5 ***< 5 ***

Contra Lung MeanContra Lung Mean 2.92.9 0.30.3 < 5< 5

Discussion

• PTV depth to cover IMC is a challenge

• IMRT advantages over 3DCRT;

– Improved Conformity of dose to PTV – Lower dose to most OARs.

• IMRT disadvantages over 3DCRT;

– Increased mean dose to heart and contralat lung – Higher integral dose

• Accurate delineation of OAR required

– Pre & Post Contrast CT for LAD (RO)

Discussion

• Limitations of this study

– Comparison of only one 3DCRT approach – ???Junctional electron technique

• Future Direction

– 11 patients treated with IMRT for breast cancer to date

– RapidArc and Respiratory Gating – IGRT match results trend review – Clinical use of breast drapes

Conclusion

• IMRT improves PTV coverage

• IMRT reduces OAR dose at expense of higher integral dose

• Wide field 3DCRT cannot achieve comparable results

• Careful selection of suitable cases is recommended

• IMRT has become the standard of care for complex

breast cancer cases

Acknowledgements

Jim Frantzis Paul Fenton

Professor Chris Hamilton Robert Lumsden

Staff at Epworth Radiation Oncology

References

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References

8. Abeyaratne D. Can intensity modulated radiation therapy reduce cardiac dose in left-sided breast patients? The Radiographer 2010; 57: 40. 9. Thilmann C, Sroka-Perez G, Krempien R, Hoess A, Wannenmacher M, Debus J. Inversely planned intensity modulated radiotherapy of the breast including the internal mammary chain: a plan comparison study. Technol Cancer Res Treat 2004; 3: 69-75. 10. Dogan N. Cuttino L. Lloyd R. Bump E. Arthur D. Optimized Dose Coverage of Regional Lymph Nodes in Breast Cancer: The Role of Intensity-Modulated Radiotherapy. Int. J. of Radiation Oncology Biol. Phys. 2007; 68: 1238-1250. 11. Dayes I, Rumble R, Bowen J, Dixon P, Warde P. Intensity-Modulated Radiotherapy in the Treatment of Breast Cancer. Clinical Oncology 2012; 24: 488-498. 12. Jagsi R, Moran J, Marsh R, Masi K, Griffith K, Pierce L. Evaluation of Four Techniques Using Intensity-Modualted Radiation Therapy for Comprehensive Locoregional Irradiation of Breast Cancer. Int. J of Radiation Oncology Biol. Phys. 2010; 78: 1594-1603. 13. Jin JY, Klein EE, Kong FM, Li Z. An improved internal mammary irradiation technique in radiation treatment of locally advanced breast cancers. J Appl Clin Med Phys 2005; 6: 84-93. 14. Taylor C, Povall J. McGale P. Nisbet A. Dodwell D. Smith J. Darby S. Cardiac Dose From Tangential Breast Cancer Radiotherapy in the year 2006. Int. J. of Radiation Oncology. Biol. Phys. 2008; 72: 501-507. 15. Louise Richter. Dose to the LAD associated with 3DCRT vs IMRT for Left sided breast irradiation. Powerpoint Presentation. 2011. 16. ICRU 83 Report.

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