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29

NCCN Guidelines for Patients

®

:

Rectal Cancer, Version 1.2017

After simulation, your radiation team will further

plan your treatment. Plans will be made by viewing

your CT scans on the treatment planning computer.

Your radiation oncologist will work closely with a

dosimetrist. They will plan the best dose, number and

shape of radiation beams, and number of treatments.

Your plan will be designed to treat the cancer while

sparing normal tissue.

Set-up session

Once your treatment plan is made, a set-up session

is needed. This session is sometimes called “port

film” day or dress rehearsal. The set-up session

occurs in the treatment room.

The radiation therapists will help place you in position

on the treatment table. The set-up marks will be used

for positioning. X-rays of the treatment fields will

be taken and viewed by your doctor. These x-rays

(or port films) are not for treatment. Your doctor will

approve treatment when your set-up is correct.

Treatment sessions

Treatment is given once a day on Monday through

Friday. Short-course radiation is finished in 5 visits.

Long-course radiation takes about 28 visits. Each

session can last between 10 to 30 minutes. In

general, treatment is received at the same time each

day.

Before treatment, you will be placed into position.

If a mold was made, you will lie on it on top of the

treatment table. You must be in the same position

that was approved at the set-up session. X-rays of

your pelvis are used to assure this.

Conformal techniques are used for treating rectal

cancer. These techniques shape the radiation dose

to the cancer site to spare healthy tissue. 3D-CRT

(

three

-

d

imensional

c

onformal

r

adiation

t

herapy)

delivers, from different angles, a photon beam that

matches the shape of the target.

Other types of conformal techniques are less often

used. IMRT (

i

ntensity-

m

odulated

r

adiation

t

herapy)

is a form of 3D-CRT. It further modifies the beam’s

intensity during treatment. IMRT is used in certain

cases.

SBRT (

s

tereotactic

b

ody

r

adiation

t

herapy) treats

cancer with very precise, high-dose photon beams.

Treatment is finished in 5 visits. At this time, SBRT is

only used to treat some people with rectal cancer in

the spine, liver, or lungs.

During treatment, you will be alone in the room. A

therapist will operate the machine from a nearby

room. He or she will be able to see, hear, and speak

with you at all times. As treatment is given, you may

hear noises. The machine will move around you to

different treatment angles. You will not see, hear, or

feel the radiation.

Intraoperative radiation

IORT (

i

ntra

o

perative

r

adiation

t

herapy) delivers

radiation inside your body during an operation.

Different methods can be used. However, the usual

method involves a device that is placed where the

tumor was. The radiation kills remaining cancer cells

in the tissue that was near the tumor.

IORT is a one-time treatment that is given while you

are still asleep. It is used to deliver extra radiation

if cancer cells may remain after surgery. This extra

radiation is called a boost. IORT uses radiation made

of electrons or lower energy x-rays. Electrons do not

travel far and are less likely to harm the tissue deep

to the treatment site.

Brachytherapy

Some cancer centers do not have an IORT machine.

In this case, a boost of radiation can be given

with EBRT, brachytherapy, or both. Brachytherapy

delivers radiation through radioactive objects that are

placed where the tumor was. The objects remain in

3

Overview of cancer treatments

Radiation therapy