quantec rt constraints

7/25/2019 QUANTEC RT Constraints

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A Review of QUANTECNormal Tissue Tolerances

MaryLou DeMarco, MS,CMD

Thomas J. Dilling, MD

Moffitt Cancer Center, Tampa FL


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Learning Objectives

Understand:

What increased knowledge the QUANTEC

effort provides over the 1991 Emami normal

tissue tolerance tables New/revised QUANTEC dose constraints,

for various organs

Incorporating new information into treatment

planning


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Normal Tissue Tolerance

The Emami paper(1991) Committee of experts to review known data,

provide guidelines

Some of the constraints we use come fromthe old Emami paper

Emami used someclinical data to suggesttissue tolerance

But back then they had comparatively poor

ability to deliver and measure the dose actuallydelivered

Some data made upbased uponeducated guesses

Emami B, et al. Int J Radiat Oncol Biol Phys 1991; 21: 109-22.


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Emami Out of Date?

Move from 2D to 3D treatment planning

IMRT, Stereotactic, higher daily doses,new TPS technology !

Higher energy beams/better penetration Improved ability to measure dose, new

algorithms, heterogeneity corrections

Increased use of combined

chemoradiotherapy Numerous additional studies of tissue

tolerance


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QUANTEC

QuantitativeAnalysis of Normal

Tissue Effects in the Clinic

Large committee of experts (n=57)

Convened by ASTRO / AAPM

Updated guidelines published in Red

Journal supplement (Vol 76, No. 3,

2010)

16 organ-specific papers

Several general principlepapers


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16 Organ-Specific Papers & 5 Vision Papers

1. Brain

2. Optic Nerve/Chiasm

3. Brain Stem

4. Spinal Cord

5. Ear

6. Parotid

7. Larynx/Pharynx

8.

Lung

9.

Heart

10.

Esophagus

11.

Liver

12. Stomach/Small Bowel

13. Kidney

14.

Bladder

15. Rectum

16. Penile Bulb

1.

True Dose2.

Imaging

3.

Bio Markers

4. Data Sharing

5. Lessons of QUANTEC


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IMPORTANT POINTS

MANY details within each paper

Explication of available data

HOW TO CONTOUR structureAffects how/whether you meet

constraints!

These are GUIDELINES

Your MDs might use somethingdifferent (tighter or looser constraints)

Discuss with your MDs!


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CNS 3D treatment planning:

Spinal Cord (QUANTEC) Brain (QUANTEC)

Chiasm/Optic Nerves (QUANTEC)

Brainstem (QUANTEC)

Cochlea/Inner Ear (QUANTEC)

Eyes (globe) (RTOG)

Lens (RTOG)

Retina (RTOG) Pituitary Gland (Emami)

Cauda Equina (Emami)

Stereotactic Radiosurgery: Spinal Cord (QUANTEC)

Brain (QUANTEC)

Brainstem (QUANTEC)

Chiasm/Optic Nerves (QUANTEC)

Sacral plexus (RTOG)

Cauda Equina (RTOG)


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Brain Data Summary


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Brain Proposed Constraints

Emami overly conservative (standard fractionation)

SRS: 20+% risk when >5-10 cc get >12 Gy

Children: 18 Gy WBRT!cognitive changes

Structure Point Max Necrosis Risk

Brain 72 Gy 5%

Brain 90 Gy 10%

Brain < 60 Gy < 3%


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Brainstem: neuropathy or necrosis

Entire brainstem can get 54 Gy

Smaller portions (1-10cc) to 59 Gy

SRS: Max 12.5 Gy = low (


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Spinal Cord: myelopathy

Full cord cross-section

Reirradiation: 25% ofdose forgotten at 6 mos

Cervical cord moresensitive than thoraciccord?

Radiation Technique Dose Myelopathy Risk

Standard Fractionation 50 Gy 0.2%Standard Fractionation 60 Gy 6%

Standard Fractionation 69 Gy 50%

SBRT (single fx) 13 Gy 1%

SBRT (3 fx) 20 Gy 1%


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Optic Nerves/Chiasm: Optic Neuropathy Standard Fractionation

Max < 55 Gy

Fraction size important

Greater age!increased risk

SRS Max


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Cochlea: hearing loss


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Cochlea: hearing loss

Other factors Cisplatinum (adjuvant or concurrent)

Consider constraining to "35 Gy

Increasing patient age

Better hearing!increased hearing loss

QUANTEC Dose recommendations: Mean "45 Gy (< 30% hearing loss)

SRS: Limit dose to "14 Gy (


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H&N: Parotids (QUANTEC)

Submandibular glands (QUANTEC)

Larynx (QUANTEC)

Pharyngeal Constrictors (QUANTEC)

TMJ/mandible (RTOG)

Oral Cavity (RTOG)

Esophagus (cervical) (RTOG)

Thyroid (Emami)


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Salivary Gland:Long-term salivary function < 25%

Much data re: parotid gland sparing

Some data re: submandibular gland sparing

Sparing 1 parotid eliminatesxerostomia (meandose < 20 Gy)

Mean dose both glands < 25 Gy

Sparing 1 submandibular gland reduces

xerostomia

Structure Dose Risk

Parotid (both) Mean < 25 Gy < 20%Parotid (both) Mean < 39 Gy < 50%

Parotid (one) Mean < 20 Gy < 20%

Submandibular Mean < 35 Gy


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Larynx: Vocal dysfunction, aspiration, edemaPharynx: symptomatic dysphagia & aspiration

QUANTEC Recommendations

Structure Constraint Risk Symptom

Larynx Max < 66 Gy < 20% Vocal Dysfunction

Larynx Mean < 50 Gy < 30% Aspiration

Larynx Mean


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CNS/H&N Guidelines CNS (200cGy/day):

Spinal Cord Max 5000 QUANTEC

Brain Max 7200 (partial) QUANTEC Chiasm/optic nerve Max 5500 QUANTEC

Brainstem Max?


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Lung


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Lung: Symptomatic Pneumonitis Factors impacting on side effects

Current smoking is protective (anecdotal)

Chemotherapy increases risk

General QUANTEC Guidelines: Limit V20 "30 35%

Limit MLD "20 23 Gy

Limit central airways < 80 Gy (stenosis)

Mesothelioma:

V5 < 50%; V20 < 4-10%; MLD < 8 Gy

Recommend LENT-SOMA scoring of symptoms

Structure Dose Pneumonitis

Lung Mean 7 Gy 5% Risk






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Heart: pericarditis & long-term cardiac mortality

Mostly breast/lymphoma data (high cure rate/long survival)

Whole heart to 3000 cGy ok without chemo (old lymphoma data)

Other factors:

Whole heart to 1500 cGy with Adriamycin

Age

Gender

Diabetes Mellitus

Smoking

High Blood Pressure

Cholesterol

Parental history of early MI

Pericarditis: Mean pericardium dose


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Heart: QUANTEC guidelines

Mean < 26 (


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Esophagus

Various metrics used in publications Mean esophageal dose

V20

V35

Max dose

Esophageal length receiving full circumference dose

Length with #7000 Gy to 75% circumference

Not possible to identify single best threshold

volumetric parameter


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Esophagus

Record V60 (Emami = V60


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Brachial Plexus

No QUANTEC data

RTOG 0619 = Max 6600

V60 < 5%


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Spinal Cord Max 5000 QUANTEC

Total Lung Mean < 2000-2300, V20


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Liver Patients (and livers) vary:

Healthy vs. unhealthy liver Primary HCC vs. metastases

Hepatitis

Portal vein thrombosis

Prior arterial chemoembolization

Concurrent chemo

Tumor stage

Male/Female

Child-Pugh score (bilirubin, albumin, ascites!)

QUANTEC Whole Liver

Mean "28-32 Gy (2 Gy fx)


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Liver - SBRT

Primary Hepatocellular Carcinoma Mean < 13 Gy (3 fx),


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Kidney

Long latency period: Toxicity under-reported?

Acute toxicity subclinical


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Kidney Recommendations

Kidney (bilateral):

V28 < 20%

V23 < 30%

V20 < 32%

V12 < 55%

Mean < 18 Gy

If mean kidney dose to 1 kidney is > 18 Gy, then

constrain remaining kidney to V6 < 30%


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Stomach/Small Bowel

How to contour small bowel

(individual loops vs one large

region in peritoneum)?

Stomach/Small Bowel move day to

day


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Stomach/Small Bowel

QUANTEC dose guidelines Stomach

D100 (whole stomach) < 45 Gy!5-7% risk ulceration

SBRT: V22.5


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GI Constraints (Conventional Fx)

Colon Max 5500 (Emami)

Structure Constraint

Liver (healthy) Mean < 3200 cGy

Liver (hepatocellular carcinoma) Mean < 2800 cGy

Kidney (bilateral) Mean < 1800 cGy

Whole Stomach < 4500 cGy

Small Bowel V45 < 195 cc


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Bladder

Poor data re: partial volume XRT(bladder motion not accounted for)

Confounding factors

Pre-RT GU toxicity Smoking history, obesity, black race

Age, DM, HTN, PID not correlative

Structure Constraint

Whole Bladder V80 < 15%





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Penile Bulb

Prudent to keep mean dose to 95% ofvolume to


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Rectum

QUANTEC dose guidelines:

V50 < 50%

V60 < 35%

V65 < 25%

V70 < 20%

V75 < 15%


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Femoral Heads V50


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Lessons from QUANTEC

Need a peer-reviewed centralrepository of

Dose-volume constraints

Contouring standardsAtlases

Contouring standards

Toxicity grading schemas

Endpoint definitions

Toxicity data/rates

From TPS, directly calculate risks of

toxicity for individual patient


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3D dose distribution

Discardspatial,

anatomical,physiological

data

Extract unambiguous data: Single-point: e.g. V20

Global: e.g. mean dose

Compute model-basedNTCP estimates


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