brachytherapy basics - aamd publications

AAMD 44th Annual MeetingJune 16 – 20, 2019

6/19/2019

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BRACHYTHERAPY BASICS

Mitchell Kamrava, MD

Residency Program Director

Director Brachytherapy Services

Associate Professor

Department of Radiation Oncology

Cedars Sinai Medical Center

Samuel Oschin Comprehensive Cancer InstituteCedars‐Sinai Medical Center

DISCLOSURES

• None


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OUTLINE

• Intro to brachytherapy basics

• Breast brachy

• Gynecologic brachy

• Prostate brachy

BRACHYTHERAPY:TREATING FROM INSIDE OUT

Brachytherapy provides

• Radiation that is close to or within the tumor

• High dose to target volume

• Sharp dose fall-off

External beam therapy works from the outside → in

Brachytherapy works from the inside → out

Edited image and rekeyed info and lines

Bladder Prostate

Radioactive seeds

Rectum

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THE EVOLUTION OF BRACHYTHERAPY

1. Gupta VK. J Med Phys. 1995;20(2):31-35; 2. Nag S. American Brachytherapy Society; 3. Aronowitz JN, et al. Brachytherapy. 2007;6:293-297; 4. Blasko JC, et al. J Urol. 1995;154:1096-1099; 5. Grimm P, et al. BJU Int. 2012;109(suppl 1):22-29; 6. Thariat J, et al. Nat Rev Clin. Oncol.2013;10:52-60; 7. Viani GA, et al. J Exp Clin Cancer Res. 2009;28:47; 8. Lukens JN, et al. Semin Oncol. 2014;41:831-847.

1901Brachytherapy first used for lupus and malignancies1,2

1903Brachytherapy first used for gynecologic cancers3

1917Techniques developed for prostate cancer4

1920sBrachytherapy widely used to treat accessible tumors with radium6

1950s-1960sNew sources, techniques, and equipment reduced patient and physician exposure to radiation leading to a renaissance for brachytherapy1

OngoingAccepted as an important treatment option with strong supporting data for numerous cancers5,7,8

1970sBrachytherapy established as safe and standard-of-care for gynecologic cancers7

BROAD CLINICAL UTILITY OF BRACHY

Bronchus, LungBreast

Bladder, Rectum

Cervix, Uterus, Endometrium,

Vagina Prostate

Gall bladder, Bile duct

Esophagus

Head & NeckTongue, Nasopharynx

Skin, surface

Female Male

Most common uses

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SPECIALIZED APPLICATORS AND AFTERLOADER

MATCHED TO TREATMENT NEEDSGynecologic Breast

Skin

Lung Prostate

Afterloader

• Applicators are placed adjacent to the tumor

• Additional needles can provide coverage outside of target area

• Useful for following body sites

• Gynecologic – cervical, endometrial, vaginal

• Rectum

• Nasopharynx

• Breast (post procedure)

INTRACAVITARY BRACHYTHERAPY APPLICATIONS

Tandem

Rectum

Bladder

Cervical Cancer

Applicator

Uterus

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INTERSTITIAL BRACHYTHERAPY APPLICATIONS

• Catheters are placed into the lesion and adjacent tissue


• Prostate

• Breast

• Head and neck

• Bladder

• Brain Template to aid accurate placement of the needles delivering the seeds

Needle, delivering seeds into prostate

Ultrasound probe in

rectum for needle

guidance

Catheter in urethra

INTRALUMINAL BRACHYTHERAPY APPLICATIONS

• Applicators are placed adjacent to the tumor


• Lung

• Esophagus

• Biliary

Radiation Zone

Cancer

Radiation Wires

Endobronchial Radiation

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SURFACE BRACHYTHERAPY APPLICATIONS

• Applicators are placed on the skin

• Useful for treatment of keloids and some types of skin cancer

BRACHYTHERAPY WORKFLOW

• Applicator placement

• Simulation

• Catheter reconstruction

• Target/OAR contouring

• Planning

• Treatment

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TEMPLATE MAPPING AND APPLICATOR DIGITIZATION

CATHETER RECONSTRUCTION

Multiple ChannelsSingle Channel

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IMAGE TECHNIQUES AND FUSION

• CT or MR based planning?

• Image fusion can be difficult

• Applicator/Catheter digitization can be tricky

• Plan can be created on CT or MR when using TG43 calculations

TARGET/OAR/CATHETER 3D RECONSTRUCTION

Images courtesy of UCSFTarget and OAR reconstruction Inclusion of catheters and possible dwell positions

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INVERSE PLANNING SIMULATED ANNEALING

Images courtesy of UCSF

PLAN OPTIMIZATION AND REVIEW

• Scripting

• Plan Quality Report

• OAR constraints

• External Beam Radiation considerations (EQD2)

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HIGH DOSE RATE (HDR) BRACHYTHERAPY –REMOTE AFTERLOADING

Iridium 192

The radiation strength is proportional to dwell time

BREAST BRACHYTHERAPY

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1-2 weeks

2 d - 1 week 2 d - 1 week

APBI RATIONALE

• Oncologic• Majority of failures are true recurrences (around where tumor started)

• Not clear that treating the whole breast reduces elsewhere failures

• Convenience • Treatment can be completed within 1 week

• Toxicity• Improved breast cosmesis• Decreased organs at risk dose (heart/lung)

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WHO IS A CANDIDATE?

WHOLE BREAST VS APBI (CAVITY + MARGIN)

SAVI Contura T+B IORT EBRT

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APBI TECHNIQUES

• Interstitial tube and button

• treatment 2 times per day for 8-10 treatments

• some early data to support just 3 treatments

• Single entry catheter devices

• treatment 2 times per day for 8-10 treatments

• some early data to support just 3 treatments

• External beam radiation

• treatment 2 times per day for 10 treatments or daily for 10 treatments

• Treatment 1 time per day for 5 treatments

INTERSTITIAL BREAST

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3D Dosimetry Distribution

SINGLE-ENTRY CATHETER DEVICES

Mammosite MammositeML Contura SAVI

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EXAMPLE OF SINGLE ENTRY CATHETER

B39 CONTOURING GUIDELINES

Brachytherapy EBRT

IS – 1.5 cm expansion on cavity

Balloon – 1.0 cm expansion on cavity

EBRT –1.5 cm CTV expansion and 1.0 cm PTV expansion

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SAVI DIAGRAM

PRESCRIPTION

• Brachy

• 3.4 Gy x 10

• 4 Gy x 8

• 7.0-7.5 Gy x 3 (early data)

• EBRT

• 3.85 Gy x 10

• 4 Gy x 10

• 6 Gy x 5

• IORT

• Xoft 20 Gy x 1 to the balloon surface

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DOSE CONSTRAINTS FOR APBI

Shah C et al. Journal Contemporary Brachy. 2016.

BREAST PQRTARGET: D90, V150, V200

OARS: SKIN, CHEST WALL, LUNG

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INTRA-OPERATIVE RADIATION THERAPY

• 1 treatment

• In the operating room

• While you are asleep

• In theory you wake up “done” with radiation

• 3D

• IMRT

• SBRT

• IORT

• Brachy

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EXTERNAL BEAM

Unacceptable Cosmesis in a Protocol Investigating Intensity-Modulated Radiotherapy With Active Breathing Control for Accelerated

Partial-Breast Irradiation

Reshma Jagsi, M.D., D.Phil., Merav A. Ben-David, M.D., Jean M. Moran, Ph.D., Robin B. Marsh, C.M.D., Kent A. Griffith, M.P.H., M.S., James A. Hayman, M.D., M.B.A. and Lori J. Pierce, M.D.

International Journal of Radiation Oncology * Biology * PhysicsVolume 76, Issue 1, Pages 71-78 (January 2010)

DOI: 10.1016/j.ijrobp.2009.01.041

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Visible impairment in cosmesis observed in 3 patients deemed to have unacceptable cosmesis after treatment.

Distribution of the proportion of the breast reference volume in each

case receiving 50% of prescribed dose (V50), by cosmetic outcome

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Whole breast V5 <70%, V50 <40%, V80 <25‐30%, V100 <15‐18%

EBRT APBI

• Can be done safely now with increased attention to spill dose to rest of breast

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GYNECOLOGIC BRACHYTHERAPY

CERVICAL CANCER ~12,000 NEW CASES &

4,000 DEATHS PER YEAR

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TREATMENT OVERVIEW

STANDARD OF CARE (SOC): EBRT + CHEMO + BRACHY

EBRT 5 weeksMon-Fri

20 min daily

Weekly Cisplatin40 mg/m2

5-6 cycles

Brachy4 treatments2 per week

Complete all treatment within 8 weeks

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ARE WOMEN RECEIVING SOC: EBRT + CHEMO + BRACHY?

Robin T et al. Gyn Onc. 2016.

NCDB analysis

15,200 pts

2004-2012

Only 44% received SOC

Improved OS w/ SOC

REDUCTION IN OS WITHOUT THE USE OF BRACHYTHERAPY

Gill B et al. IJROBP. 2014.

INC IN USE OF IMRT/SBRT BOOST DEC IN OVERALL SURVIVAL

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WHY IS BRACHYTHERAPY SO IMPORTANT?LOCATION, LOCATION , LOCATION

• Inside out approach with brachy allows:

• Higher dose to the tumor

• Less dose to the bladder, rectum/sigmoid, and small bowel

BLADDER

RECTUM

TUMOR

MOVING FROM 2D FLUOROSCOPY TO 3D CT/MRI BASED PLANNING

2D

3DCT

3DMRI

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2D PLANNING

Where is the tumor?

Where is the rectum/sigmoid/bladder?

PROBLEM WITH POINT BASED RX

TUMOR UNDER VS OVER COVERAGE

Point A

POINTS CAN UNDERESTIMATE DOSE TO BLADDER AND RECTUM

100% isodose

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NATIONAL TREND TOWARDS VOLUME BASED TREATMENTS

STANDARDIZING VOLUME BASED DEFINITIONS

White – Gross disease (GTV)

Yellow – High Risk Target (HR-CTV)

Orange –Intermediate Risk Target (IR-CTV)

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Slide adapted from Richard Potter

VOLUME VS POINT BASED PRESCRIPTION

HR-CTV

BLADDER

RECTUM

YELLOW LINE –100% of dose

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LIMITATIONS OF STANDARD 3 CHANNEL APPLICATORS

3 channels adequate

Red – tumor Orange – 100% radiation dose

3 channels NOT adequate Coverage adequate with more channels

APPLICATORS THAT ALLOW NEEDLES

Vienna UtrechtSyed/MUPIT

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EXAMPLE OF HOW EXTRA NEEDLES IMPROVE TUMOR COVERAGE

CERVICAL CANCER PLANNING GOALS

• HR-CTV 80-85 Gy (D90 > 85 Gy)

• Most commonly after 45 Gy, 6 Gy x 5 or 7 Gy x 4

• Rectum D2cc < 65 Gy (ideal), < 75 Gy (max)

• Bladder D2cc < 80 Gy (ideal), < 90 Gy (max)

• Sigmoid/Bowel D2cc < 70 Gy (ideal)

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VAGINAL CYLINDERS

Most common indication: Post-op Endometrial

Slide courtesy of Manjeet Chadha

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Slide courtesy of Manjeet Chadha

Brachytherapy. 2015.

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PROSTATE BRACHYTHERAPY

Modern Radiation Therapy

Brachytherapy

Low Dose RatePermanent Seeds

High Dose RateVirtual Seeds

External Beam

9 weeksStandard Fractionation

4-5 weeksHypofractionation

1.5 weeksSBRT

TREATMENT OPTIONS

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HIGHER DOSES OF RADIATION TO THE PROSTATE IMPROVE CHANCES OF PSA

CONTROL

Meier R. Front Oncol. 2015.

?


HOW HIGH DO WE NEED TO GO?

BED 200?

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HOW CAN YOU GET TO A BED

OF 200?

SBRT

LOCATION, LOCATION, LOCATION

• Brachy provides a solution to safely dose escalate while limiting dose to OARs

• How high can we safely go?

• How high do we need to go?


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HDR PROSTATE PRESCRIPTION

• Monotherapy (Brachy alone,13.5 Gy x 2)

• Low

• Favorable intermediate risk

• Combination (Brachy+EBRT, 15 Gy x 1 + 45 Gy)

• Unfavorable intermediate risk

• High risk

• Salvage (local failure after prior EBRT)

• 11 Gy x 2

PQR FOR PROSTATE HDR

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LOGISTICS OF BRACHYTHERAPY

• Done in the operating room

• Spinal/Sedation vs General

• ~1 hour

• LDR – all seeds placed in OR

• HDR – treatment given later that day, second treatment next day/week (for monotherapy)

TRUS GUIDED PLACEMENT OF CATHETERS

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HDR BRACHYTHERAPY ULTRASOUND VS CT BASED PLANNING

Ultrasound planning – 2 implants, 1-2 weeks apartTreatment done when you wake up

CT based planning – 2 implants, 1-2 weeks apart vs 1 implant w/ overnight stay and treat next day

Treatment not done when you wake up

HDR Brachytherapy

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CONCLUSIONS

• Brachytherapy is a versatile tool that can be helpful in many disease sites

• It’s most commonly used in breast, gyn, prostate, and skin cancers

• It provides conformal dose to targets while limiting dose to surrounding OARs

• Safe/effective planning requires teamwork between MD, physicist, dosimetrist and therapist

• Brachytherapy is fun “team sport”!!

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brachytherapy basics - aamd publications

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