Radiotherapy Techniques

 
 

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A] MANTLE

  • Planning Target Volume

This includes the occipital, submental, submandibular, anterior amd posterior cervical and supra-cavicular nodes. In addition, it covers the infrra-clavicular, axillary, medial-pectoral, paratracheal and mediastinal lymph nodes.

Standard field from tip of mastoids to bottom of T10

Mark involved nodes on the simulator

No humeral shielding on ipsilateral side if node involvement, otherwise - Standard humeral shield

Cervical cord shielding from posterior field from 20 Gy unless it is close to involved nodes (To bottom of C7).

Dorsal spine shielding from posterior field from 30 Gy mpd unless a mediastinal mass is present which was not treated with prior chemotherapy. Anterior shield to cover larynx (bottom of C5)

Allow adequate clearance of infraclavicular nodes, i.e. 2cm below clavicle.

Lateral border follows inside of rib cage with approx 0.5 cm lung showing laterally or lower border 4th rib

8-10 cms width to allow clearance of retrocrural nodes.

Patient treated supine and prone at 142cm FSD or supine and undercouched at 100-110cm FSD

  • Standard dose

Routine - 35 Gy mpd in 20# in 4 weeks specified at mid point tattoo. Boost to 45 Gy to involved field in NHL. Dose plotted for neck/supraclav., axillae and field centre and areas should not exceed 40 Gy in NHL and 35Gy in Hodgkin’s. In order to reduce the axillary dose the treatment width may be reduced to the inner aspect of the humeral head (if no axillary disease) for the last 1-2 fractions. In order to reduce the neck dose the upper boarder of the field may be reduced to the sternal notch (provided no cervical disease) for the last 1-2 fractions. NB If this is contemplated, the patient must be planned and treated on a machine which has full asymmetrical diaphrams.

Post chemotherapy - 6 week gap between chemotherapy and radiotherapy. Dose to previously involved site(s) to 35 Gy in 17#.

[B] INVERTED Y

  • Planning target volume

Para-aortic, pelvic, inguinal nodes and spleen.

Standard field bottom of T10 to bottom of ischial tuberosities (appropriate gap calculations from previous mantle field). Check clinically that inguinal nodes included.

Paraaortic strip 8-10 cm wide to cover nodes at renal hila (plan with IVP)

Pelvic field to cover iliac node chains.

Shielding Midline pelvic sheilding - bladder, small bowel, uterus and ovaries if transposed.

Lateral blocks - small bowel , kidneys.

Scrotal shielding - testes

Standard dose Routine - 35 Gy mpd in 20# in 4 weeks. Boost to 40 Gy to involved field in NHL

Post chemotherapy - 35 Gy in 17# only.

Palliative RT 20-25 Gy/10F or 20Gy/5F.

[C] INVOLVED FIELD RADIOTHERAPY

  • Planning traget volume

Mark involved nodes on the simulator

Map out radiologically involved areas from pre-treatment scans on simulator film.

Put in target volume to include involved nodes + 1-2cm laterally + 5cm along node chain.

  • Standard doseRoutine - 35 Gy mpd in 20# , 4 ks. Boost to 40 Gy involved field, NHL

Post chemotherapy - 35 Gy in 17# only.

Palliative RT 20-25 Gy/10F or 20Gy/5F.

CARE OF PATIENT DURING RADIOTHERAPY

Patients to be reviewed weekly during radiotherapy including weight and FBC. Prophylactic antiemetic given to abdominal fields. Metochlopramide or domperidone 10-20mg tds. If vomiting occurs for U&E’s. Dysphagia - mucaine, Nystatin 1ml qds and aspirin mucilage.

Diarrhoea and colicky abdominal pain - Low fibre diet. Loperamide.


Further general information Your doctors and specialist nurses are in an ideal position to give you relevant information on your disease and treatment as they know your individual circumstances. Cancerbackup has a help line (0808 800 1234) and a prize winning video available in English, Italian, Urdu, Bengali, Gujarati & Hindi explaining Radiotherapy & Chemotherapy. Cancernet.co.uk has over 500 pages describing cancer, its management, practical tips and tool which patients, their carers and their doctors have found helpful during the cancer journey.


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