Student Name: Sonia khan
Course: Access to sciences
Unit: Health physics (Assignment
the use of ionising radiation, ultrasound and lasers in medical treatment.
and evaluate the use of a given modern imaging techniques in a given treatment.
occurs when cells in the body undergo a mutation that causes them to grow
rapidly and uncontrollably. Lung cancer forms when cancer cells invade and
destroy healthy cells in the lung tissues and air passages. It can take several
years to develop. It may begin as pre-cancerous changes in the lungs that
neither cause symptoms nor show up on an X-ray.
cancer cells accumulate to form a tumour. As the tumour grows, it impedes the
ability of the lungs to function properly. Cancerous cells can break away from
the original tumour, travel through the bloodstream, and form tumours in other
parts of the body. This process is called metastasis.
ionising radiation can cause cancer, high doses can be directed at cancerous
cells to kill them. This is called radiotherapy. About 40 per cent of people
with cancer undergo radiotherapy as part of their treatment. It is administered
in two main ways:
v From outside the body using x-rays or
the radiation from radioactive cobalt.
v From inside the body by putting
radioactive materials into the tumour, or close to it.
two main types of lung cancer. They are small cell and non-small cell. The
names refer to how the cells appear to pathologists under a microscope. Each
type and stage of lung cancer warrants unique treatment options.
Small Cell Lung Cancer (SCLC)
lung cancer accounts for 15 percent of all lung cancers. Small cell lung cancer
starts in neuroendocrine cells. These are the air tubes that lead to the lungs
(the bronchi) and the cells in lung tissue. It grows very quickly. It produces large
tumours that can travel through the blood and spread quickly throughout the
body. Small cell lung cancer mainly affects heavy or lifetime smokers.
two main types of small cell lung cancer. They are small cell carcinoma (oat
cell cancer) and combined cell carcinoma.
Oat cell cancer is the most common type of
small cell lung cancer. The cells resemble oats when examined under a
Non-Small Cell Lung
cell lung cancer makes up about 85 percent of all lung cancer cases in the
United States. The cancer cells are larger, and the cancer is slower growing
than small cell lung cancer. NSCLC consists of three subtypes:
• Squamous cell carcinoma (or epidermoid
carcinoma) accounts for 25 to 30 percent of all lung cancer. It begins in the
cells that line the air passages. If not treated it may spread to the lymph
nodes, bones, adrenal glands, liver, and brain. It’s the most common type of
lung cancer in men and is heavily linked to smoking.
• Adenocarcinoma makes up about 40
percent of all lung cancer. It forms in the mucus-producing (outer) part of the
lungs. It develops slowly and is the most common type of lung cancer in women
• Large-cell (undifferentiated)
carcinoma includes all non-small cell lung cancer that can’t be classified as
squamous or adenocarcinoma (about 10 to 15 percent). It sometimes forms near
the surface, in the outer edges of the lungs, and grows rapidly. (Medicine.et)
Lung cancer symptoms do not usually
present themselves until the cancer is advanced. This is why lung cancer often
goes undetected in the early stages. Lung cancer symptoms include:
• Persistent cough
• coughing up blood
• Chest pain
• Recurring chest infections
• Voice hoarseness
Figure 1: A Chest x-ray showing a
tumour in the lung
therapy is the delivery of focused high-energy x-rays (photons), gamma rays or
atomic particles. It affects cells that are rapidly dividing, such as cancer
cells and much more than those that are not. Most cancers, including lung
tumours, are made of cells that divide more rapidly than those in normal lung
tissue, holding out the hope that the tumour can be eliminated without damaging
surrounding normal tissues. Radiotherapy acts by attacking the genetic
material—or DNA—within tumour cells, making it impossible for them to grow and
create more cancer cells. Normal body cells may also be damaged—though less
markedly—but they are able to repair themselves and function properly once again.
The key strategy is to give daily doses of radiation large enough to kill a
high percentage of the rapidly dividing cancer cells, while at the same time
minimizing damage to the more slowly dividing normal tissue cells in the same
attacking the tumour, radiotherapy can help to relieve some of the symptoms the
tumour causes such as shortness of breath. When used as an initial treatment
instead of surgery, radiotherapy may be given alone or combined with
chemotherapy. Today, many patients who have a small localized lung cancer, but
who are not candidates for surgery, are being treated with a radiation
treatment technique known as stereotactic body radiation therapy (SBRT).
Patients who are poor candidates for surgery include the elderly, patients with
chronic heart failure, and patients receiving a blood thinning drug that puts
them at risk of surgical bleeding. SBRT involves treatment with a multitude of
small, focused radiation beams tracking the lung tumour along with its
respiratory movement, typically in three to five treatments. This treatment
delivers very high doses of radiation therapy to the lung cancer in patients
where surgery is not an option. SBRT is primarily used in the setting of early
stage, localized disease. (Cancer research)
Most often, radiation therapy is
delivered by the external beam technique, which aims a beam of x-rays directly
at the tumour. Treatment is given in a series of sessions, or fractions,
usually over six to seven weeks for conventional treatments, and over one to
five treatments for patients that can be treated with SBRT. Three-dimensional
conformal radiation therapy or intensity-modulated radiation therapy (IMRT) are
fairly new techniques based on a 3-D image of the tumour taken with CT
scanning. This image serves as the target for a high-dose radiation beam that
can change in shape and size to match the tumour. This method minimizes
radiation exposure of nearby normal lung tissue.
Radiation therapy equipment used for lung cancer patients
radiation therapy can be damaging to the body and cause unpleasant side
effects, such as:
v Temporary loss of appetite is a
v Skin irritation is the rule after a
few weeks of radiation therapy. The affected area may be reddened, dry, tender
and itchy. This reaction can become quite severe during a long course of
v An inflammation of the lungs called
radiation pneumonitis may develop three to six months after radiotherapy is
over. It causes coughing and shortness of breath as well as fever but in most
cases calls for no specific treatment and gets better within two to four weeks.
v Esophagitis, inflammation of the tube
that conveys food from the mouth to the stomach, is common after radiotherapy
for lung cancer and can be severe. The oesophagus is very sensitive to
radiation, and worse damage occurs in patients who also receive chemotherapy.
Esophagitis makes it difficult to swallow and some patients have lost 10
percent or more of their body weight as a result.
a noncontagious skin condition that produces plaques of thickened, scaling
skin. The dry flakes of skin scales are thought to result from the excessively
rapid proliferation of skin cells triggered by inflammatory chemicals produced
by specialized white blood cells called lymphocytes. Psoriasis commonly affects
the skin of the elbows, knees, and scalp.
have such mild, limited psoriasis that they may not even suspect that they have
the disease. Others have very severe psoriasis that affects their entire body
considered an incurable, long-term (chronic) skin condition. It has a variable
course, periodically improving and worsening. It is not unusual for psoriasis
to spontaneously clear for years and stay in remission. Many people note a
worsening of their symptoms in the colder winter months.
types of psoriasis exist. These include:
v Plaque psoriasis: The most common form, plaque psoriasis causes
dry, raised, red skin lesions (plaques) covered with silvery scales. The
plaques itch or may be painful and can occur anywhere on your body, including
your genitals and the soft tissue inside your mouth. You may have just a few
plaques or many.
v Nail psoriasis: Psoriasis can affect
fingernails and toenails, causing pitting, abnormal nail growth and
discoloration. Psoriatic nails may become loose and separate from the nail bed
(onycholysis). Severe cases may cause the nail to crumble.
v Scalp psoriasis. Psoriasis on the
scalp appears as red, itchy areas with silvery-white scales. The red or scaly
areas often extend beyond the hairline. You may notice flakes of dead skin in
your hair or on your shoulders, especially after scratching your scalp.
v Guttate psoriasis: This primarily
affects young adults and children. It’s usually triggered by a bacterial
infection such as strep throat. It’s marked by small, water-drop-shaped sores
on your trunk, arms, legs and scalp. The sores are covered by a fine scale and
aren’t as thick as typical plaques are. You may have a single outbreak that
goes away on its own, or you may have repeated episodes.
v Inverse psoriasis: Mainly affecting
the skin in the armpits, in the groin, under the breasts and around the
genitals, inverse psoriasis causes smooth patches of red, inflamed skin. It’s
worsened by friction and sweating. Fungal infections may trigger this type of
Psoriasis signs and symptoms can vary from person to person
but may include one or more of the following:
v Red patches of skin covered with
v Small scaling spots (commonly seen in
v Dry, cracked skin that may bleed
v Itching, burning or soreness
v Thickened, pitted or ridged nails
v Swollen and stiff joint
3: Skin showing psoriasis
is option for treating psoriasis: excimer lasers, which deliver ultraviolet
light to localized areas of the skin.
treatment uses intense, focused doses of laser light to help control areas of
mild to moderate psoriasis without harming healthy skin around them. Targeted
laser therapy is similar in effectiveness to traditional light therapy, but it
works in fewer sessions with stronger doses of light that can reach deeper into
the affected skin. The handheld laser wands are also good for reaching
psoriasis in hard-to-treat areas, such as the elbows, knees, palms of the
hands, soles of the feet, and scalp.
for psoriasis use one of two types of lasers: a pulsed dye laser (PDL) or an
lasers create a concentrated beam of yellow light. When the light hits the
skin, it converts to heat. The heat destroys the extra blood vessels in the
skin that contribute to psoriasis, without harming nearby skin.
4: pulsed dye laser
lasers aim a high intensity ultraviolet B (UVB) light dose of a very specific
wavelength — 308 nanometres — directly at the psoriasis plaques. Because the
laser light never touches the surrounding skin, it reduces the risk of UV
radiation exposure. Excimer lasers are used to treat mild-to-moderate
With excimer laser therapy, patients
usually have two treatments lasting 15-30 minutes each week for three or more
weeks, with at least a 48-hour break between treatments. With pulsed dye laser
therapy, sessions go for 15-30 minutes every three weeks. (WEBMD)
Figure 5: Excimer laser used
to treat psoriasis
As well as
treating this skin condition, it also has some side effects which include: redness, skin discoloration, and sores,
though these side effects are generally mild.
is a broken bone. It can range from a thin crack to a complete break. A bone
can fracture crosswise, lengthwise, in several places, or into many pieces.
Typically, a bone becomes fractured when it is impacted by more force or
pressure than it can support.
two types of fractures: open and closed.
In an open
fracture, the ends of the broken bone tear the skin. When the bone and skin are
exposed, they are at risk of infection. This type of fracture is also called a
In a closed
fracture, the broken bone does not break the skin. This type of fracture is
also called a simple fracture. But these fractures can be just as dangerous as
open fractures. Both types require medical attention. (HEALTHLINE)
fractures are accompanied by intense pain when the injury occurs. This
discomfort can become worse when the injured area is moved or touched. Some
people may pass out from the initial pain of a fracture.
feel dizzy or chilled from shock. Common symptoms that accompany a fracture
v The sound of a snap or grinding when
the injury occurs
v Swelling, redness, and bruising in
the injured area
v An injured area that appears deformed
or has a portion of the bone pushing through the skin. Figure 6:
Bones fractured in different ways
Therapeutic ultrasound is a modality
that has been used by physiotherapists since the 1940s. Ultrasound is applied
using the head of an ultrasound probe that is placed in direct contact with
your skin via a transmission coupling gel.
Therapeutic ultrasound used to treat fractured bone
of ultrasound via an increase in local blood flow can be used to help reduce
local swelling and chronic inflammation and promote bone fracture healing.
ultrasound waves are generated by a piezoelectric effect caused by the
vibration of crystals within the head of the probe. The ultrasound waves that
pass through the skin cause a vibration of the local soft tissues.
vibration or cavitation can cause a deep heating locally though usually no
sensation of heat will be felt by the patient. In situations where a heating
effect is not desirable, the ultrasound can be pulsed rather than continuously
ultrasound treatment will take from 3-5 minutes. In cases where scar tissue
breakdown is the goal, this treatment time can be much longer. During the
treatment the head of the ultrasound probe is kept in constant motion. If kept
in constant motion, the patient should feel no discomfort at all.
ultrasound is thought to affect the tissue repair process and so it is also
highly possible that it may affect diseased tissue in an abnormal fashion. In
addition the proposed increase in blood may also function in spreading
malignancies around the body. Therefore a number of contraindications should be
followed when using therapeutic ultrasound.
imaging uses low doses of radioactive substances linked to compounds used by the
body’s cells or compounds that attach to tumour cells. Using special detection
equipment, the radioactive substances can be traced in the body to see where
and when they concentrate. Two major instruments of nuclear imaging used for
cancer imaging are PET and SPECT scanners.
emission tomography (PET) scan creates computerized images of chemical changes,
such as sugar metabolism, that take place in tissue. Typically, the patient is
given an injection of a substance that consists of a combination of a sugar and
a small amount of radioactively labelled sugar. The radioactive sugar can help
in locating a tumour, because cancer cells take up or absorb sugar more avidly
than other tissues in the body.
receiving the radioactive sugar, the patient lies still for about 60 minutes
while the radioactively labelled sugar circulates throughout the body. If a tumour
is present, the radioactive sugar will accumulate in the tumour. The patient
then lies on a table, which gradually moves through the PET scanner 6 to 7
times during a 45-60-minute period. The PET scanner is used to detect the
distribution of the sugar in the tumour and in the body. By the combined
matching of a CT scan with PET images, there is an improved capacity to
discriminate normal from abnormal tissues. A computer translates this
information into the images that are interpreted by a radiologist.
may play a role in determining whether a mass is cancerous. However, PET scans
are more accurate in detecting larger and more aggressive tumours than they are
in locating tumours that are smaller than 8 mm and/or less aggressive. They may
also detect cancer when other imaging techniques show normal results. PET scans
may be helpful in evaluating and staging recurrent disease (cancer that has
come back). PET scans are beginning to be used to check if a treatment is
working – if a tumour cells are dying and thus using less sugar.
PET, single photon emission computed tomography (SPECT) uses radioactive
tracers and a scanner to record data that a computer constructs into two- or
three-dimensional images. A small amount of a radioactive drug is injected into
a vein and a scanner is used to make detailed images of areas inside the body
where the radioactive material is taken up by the cells. SPECT can give
information about blood flow to tissues and chemical reactions (metabolism) in
procedure, antibodies (proteins that recognize and stick to tumour cells) can
be linked to a radioactive substance. If a tumour is present, the antibodies
will stick to it. Then a SPECT scan can be done to detect the radioactive
substance and reveal where the tumour is located.