Breast technique Flashcards
What are the signs and symptoms of breast cancer?
- Breast or Axilla lump
- Changes in shape or size
- skin changes: puckered, redness or peau d’orange
- Nipple changes: Inverted, discharge or ulcers
Factors associated with breast cancer?
- Being female
- Increasing age
- Personal or family history
- Inherited genes
- radiation exposure
- Alcohol
- menopause or children at older age
Is nipple retraction normal?
- It can be if doctor is satisfied no abnormality (only 1 in 100 may become sinister)
- may indicate cancer behind areola
Late signs include?
- Bone pain
- Nausea
- Weight loss
- Pleural effusion:cough or dyspnoea
- Jaundice
- Double vision`
Patient setup?
- Comfortable
- Supine, arms out of beam
- headrest, elbow, armrests, knee support and footboard
- reduce skin folds
How can you reduce lung dose?
Make sure sternum is flat
How can you reduce heart dose?
Move arms out of field moves breast superiorly
How can we reduce the need for collimator angulation?
Inclined plane to bring the chest wall parallel to the treatment couch
How can we reduce skin folds in SCF?
Move neck away from treatment field
What are considerations for women with large or pendulous breasts?
Prone or immobilisation such as breast casts
Procedures completed during CT simulation
Record all Board Settings
RO to mark up ME, LE, SUP & INF limits
RO to mark Electron Boost
Using readout on scanner, find central axis (Half way between SUP & INF)
Place radio-opaque markers on RO’s marks so as to visualise on CT
What are the benefits of a breast cast?
- Loss of skin sparing effect
- reduces severity of skin reaction in inframmamary fold
- Moves lateral and anterior part of breast anterior from OAR
What are the issues with a prone setup?
- under dosage of medial and lateral borders of PTV
- Patient’s ability to lie prone
- distinguishing between obese or pendulous breasts.
- cannot treat lymph nodes or bilateral tumours
- Large CT bore
What are appropriate limits for CT simulation?
Superior - chin of neck
inferior-5cm below breast tissue
Why are CT limits important
prognostic factor for determing fibrosis or pneumonitis using DVH
What measurements should be placed on the central slice?
Three reference tattoos are placed on the central slice and in the medial and lateral positions on right and
left sides so that measurements can be made to subsequent beam centres
-index breast board
What are the critical structures for breast treatment?
Heart
Lung
Contralateral breast
What is an appropriate slice thickness?
2-3mm
What are some planning considerations?
- Tumour bed delineated by gold seeds or titanium clips
- CLD no less than 2cm
- LAD should be excluded
- MHD no less than 1cm
- consider cardiac shielding
What are the different techniques for breast treatment?
- Forward planning field in field out both supine and prone
- DIBH IMRT
- VMAT
Why would we consider a higher energy beam?
- Large separation
- Deep seated tumours
What are some common breast volumes?
- Whole breast after BCS
- Chest wall after masectomy
- Nodal irradiation:-SCF, Axilla and IM
Where should the isocentre be defined?
- Within treatment volume
- can be at mid-separation between medial and latral edges
- Can be placed at the superior border for SCF irradiation
How can beam divergence be reduced to the lungs
Using posterior zero jaws
What are DRRs used for?
- To help determine the volume of lung tissue treated.
- Cannot exceed 2cm may require MLC shielding
What are the field margins for SCF treatment?
Inferior-2nd costal cartilage
Medial-1-2cm off midline
Lateral-coracoid process
-Superior-cricoid cartilage
Prognostic factors for SCF?
- Lymphovascular Invasion
- Extracapsular Extension
- The number and level of involved axillary nodes
- General Indication: Greater than 4 axillary nodes involved then SCF RT is indicated!
What is a SCF-junction technique?
A technique with a single isocentre at depth on the match plane uses asymmetric collimation, but restricts the maximum wedged length of the breast tangential beams.
What is the maximum field wedge that can be used?
15-20cm
What is the rationale for Electron boost treatment?
Local recurrence usually occurs around primary site tumour bed
Randomised trials have shown benefit of addition of boost
Common fractionation for EB?
10 Gy in 5
14Gy in 5
16Gy in 10
What are some considerations for EB?
- Minimise heart dose
- small wedged MV beams can be used for larger volumes or deeper margins
How is electron energy chosen?
The electron energy is chosen using CT, simulator-CT or ultrasound to measure depth of the target volume, which should be encompassed by the 90 per cent isodose
What is a standard EB diameter
5-8cm with a 7-10cm electron applicator for lateral penumbra
What is a common breast prescription?
50 in 25 for tangents
10 in 5 to electron boost
What is hypofractionation?
Radiation treatment in which the total dose of radiation is divided into large doses and treatments are given less than once a day.
What are the benefits of Hypofractionation?
Decreased overall treatment time for patient
Reduction in waiting times
Increased number of patients treated per year
What are the common Hypofractionation prescriptions?
42.5 in 16
41.6 in 13 over 5 weeks
40 in 15 over 3 weeks +/- a boost
What is the Hypofractionation criteria
- Invasive breast cancer treated with Lumpectomy and had pathologically clear resection margins
- Lymph Node Negative
- Tumour <5cm
- Breasts <25cm width
- No bilateral disease
What are some partial breast treatments?
-Brachytherapy – interstitial, Intracavity, intraoperative
Mammosite
-TARGIT – Superficial therapy small distance of dose delivery
-ELIOT – Intraoperative electron beam
-As well as 3DCRT to partial volumes
What is the criteria for partial breast treatment?
- greater than 60yrs
- tumour size <2cm
- No margins, LNS or chemotherapy
What is the image verification commonly used?
First three daily fractions and then weekly checks, with images being compared with the CT-generated DRR or simulator films
What are the common images taken?
Medial and lateral BEV tangents
What is the tolerance on the CLD/ isocentre?
5cm
What is CFD, CLD AND ICM?
CFD: Central Flash distance
CLD: Central Lung Distance
ICM: Inferior Central-axis Margin
What is the effects of slow CT helical speed?
- Blurring
- Poor DRR quality
What are the side effects of treatment?
Acute-Skin changes
Late-Breast oedema, shrinkage, pain, telangiectasia
What are the skin severity gradings?
RTOG 1- dry desquamation RTOG-2-Tender or bright erythema RTOG 2.5- Moist desquamation RTOG3- moist desquamation, oedema RTOG4- Ulceration, haemorrphage
Patient care treatment for skin reactions?
Monitor closely Moisturise Steroid creams No Gentlan violet No soap
