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The correct choice is (b) 19,999.9999

Explanation: N = N0 e ^-λt where N = particles left after DECAY, N0 is the original number of particles, t is the TIME DURATION and λ is the decay constant. Thus, putting the values in the FORMULA, we GET :

N = 20000 * e^(- (4.916* 10^-17) * 365*100*24*60*60)= 19999.99999.

Correct choice is (a) True

To elaborate: For a tumour to keep growing, it needs OXYGEN and FOOD. Otherwise, the tumour will die out. Initially, the tumour takes in oxygen and nutrients from the surrounding or the same CELLS which causes necrosis. As it spreads out, it finally comes in contact with blood vessels which ensures that the tumour receives blood which PROVIDES it with oxygen and nutrients. Thus, the oxygen LEVELS in the tumour regions are higher than normal.

Correct answer is (b) Linear Accelerator

Best EXPLANATION: Linear accelerator, ALSO CALLED as linac is used to destroy the cancer cells with the help of radiations. Higher and more sophisticated versions can destroy at the surface level itself and use electrons RATHER than photons. The linac used the photons and the electrons to damage the DNA of the cancerous cells. Non cancerous cells are able to repair their DNA but the cancerous cells FAIL to do so.

Correct option is (b) 24948 per hour

Explanation: HALF LIFE is and decay constant are related by t ^1/2 = ln2/λ

t ^1/2 = 0.693/λ

Since the half life is given in SECONDS, appropriate conversions are used for hours, minutes and day. By this, we GET:

λ = 0.693*3600/t^1/2 = 249480 per hour.

Right option is (c) 1 Rad ≈ 1 Rem ≈ 1 R

Easy EXPLANATION: All three UNITS have almost the same values and they all are units and doses of radiations. Rad stands for radiation absorbed dose and it measures the radiation absorbed by the tissues of the body. Rem is radiation equivalent and it measures the biological DAMAGE caused by DIFFERENT types of radiation.R is for Roentgens and is used as a UNIT for X – Rays.

Right choice is (d) Pair Production and Disintegration

Explanation: In pair production, an INCOMING photon of 1.02 MeV REACTS with the nucleus and disintegrates into a positron and negatron. Positron due to high energy and LOW mass gets REPELLED from the nucleus and on meeting an electron, annihilation takes place. In disintegration, a high energy photon is absorbed by the nucleus which makes it EXCITED and radioactive. To become stable again, it emits various radiations. Since both these techniques emit a large variety of radiations, they are used to destroy the cancerous cells and thus used for therapeutic purposes.

The correct option is (b) 0.7 – 3.3 MHz

Best explanation: The ultrasound treatment can penetrate up to 2 – 5 cm deep WITHIN the SKIN to RELIEVE pain. The frequency of 0.7 – 3.3 MHz is used. If the frequency is increased, it can CAUSE excess heat CAUSING heat burns in the body and doing damage rather than therapy.

Correct answer is (c) Palliative TREATMENT

Explanation: This kind of treatment is done to reduce the EFFECT and symptoms of CANCER in the body. For eg, treating the cancerous cells in the oesophagus to ALLOW the person to swallow better and EAT properly. It is done in the spinal region to stop the impingement of the nerves and reduce pain.

Correct answer is (a) Surgical and THERAPEUTIC

The explanation is: Diathermy is a PROCESS by which the body is treated by the electromagnetic WAVES or waves of high frequency. These waves beyond CERTAIN frequencies have heating effects and can help in easing the pain in the body. This type of diathermy is used for therapeutic purposes. When the heat is increased and concentrated at a point, it can cause cutting action by boiling and BURNING the cells. This type of diathermy is used for surgical purposes.

Right CHOICE is (c) Bremsstrahlung Radiation

The best I can explain: When an electron moves towards the body, it has charge and energy. On collision with the body, it RELEASES some of its energy and CHANGES its DIRECTIONS. This released energy is given out as radiation. This is Bremsstrahlung Radiation.

The CORRECT option is (b) Rem

For explanation I would say: Rem is also a forming unit of radiation. It is used to MEASURE the amount of exposure to radiation the person has had and determine if it is WITHIN safe limits or beyond it. If the safety limits have been crossed, the person must stay away from the radiology area for a SPECIFIC period of TIME of quit working there altogether.

Right OPTION is (a) The cell with OER 2.5

Best explanation: The cells that have a lower OER are more sensitive to radiation. This is because a higher amount of DOSAGE is required to DESTROY the cell in hypoxic condition as COMPARED to the amount of dosage required to do the same damage in oxygenated condition.

Correct answer is (a) CAPILLARIES

Best explanation: Same as other tissues, the capillaries which have fast dividing CELLS are more SUSCEPTIBLE to radiations. The cardiac MUSCLES, arteries, and veins are more STABLE as they are mature cells and so are not so easily damaged.

The correct answer is (c) Compton and Photoelectric

The EXPLANATION is: In Compton effect, an INCOMING photon transfers a part of the energy to the outermost electron and then scatters off. The electron may get ejected from its shell and come out and is CALLED the Compton electron. In the photoelectric effect, the incoming photon comes and removes the electron and ceases to exist. This photoelectron interacts with the various atoms and atomic particles by ionizing, energizing etc. The energies given off in these processes is recorded and used for DIAGNOSTIC purposes.

The correct choice is (d) > 1000 rad

To explain I would SAY: Various studies show that more MATURE a cell, higher is its RESISTANCE to radiations. Nerve cells and muscle cells show high resistance to radioactivity. Nerve cells once generated, they stay for a long period of time. Thus, they are highly mature cells and so provide high resistance to the radioactivity.

The correct choice is (a) radiotherapy

The best I can EXPLAIN: Radiotherapy is the process by which the cancerous cells of the BODY are KILLED. They USE radiations mostly X – Rays and sorts. Sometimes, chemotherapy and radiotherapy are combined together. Chemotherapy uses DRUGS to reduce the activity of the cancerous cells while the radiotherapy destroys them.

Correct choice is (C) It regulates the work of free radicals

The best I can explain: When radiation STRIKES the cells, it ionizes the water molecules and they break into H and OH ions. These ions are CHARGED with energy due to the radiations and they attack the DNA of the cancerous cells and damages them. In the presence of OXYGEN, this process is accelerated and also the damage inflicted on the DNA is brought under control. The oxygen reacts with the free hydrocarbon particles and fills up the gaps in DNA allowing it to recover properly.

Right choice is (a) Short wave, micro wave and ultrasound

The explanation: Shortwave diathermy USES the infrared heat waves to treat the patient while microwaves go inside the body and produce heat for treatment. Ultrasound ALSO produces SOUND waves which TRAVEL in the body, produce heat and cause HEALING.

The correct answer is (b) pads are USED for GROUNDING and completing the circuit

The best I can explain: Diathermy machines produce electromagnetic waves and the current used to produce these waves is huge. In case of any accidents, the person on whom diathermy is being performed and the one who is PERFORMING it, both can GET severely injured. Thus, electrode gel and pads are both used for diathermy, surgical and therapeutic.

Correct choice is (c) Enhancement effect of oxygen in presence of therapeutic radiation

The explanation is: When the RADIATIONS are used to destroy the cancerous cells, they INFLICT a CERTAIN amount of DAMAGE on the cells at a certain dosage. The same amount of damage is inflicted upon them at a lower dosage in the presence of oxygen. This is called Oxygen effect. It is calculated as a ratio between the damage done in hypoxic conditions to the damage in oxygen conditions.

Right choice is (a) short wave

To explain I WOULD SAY: The short wave diathermy produces heat by sending in infrared waves. These waves are produced by the plates or COILS that are placed around the area to be treated. These heat waves can travel deeper into the body than the waves produced by microwave diathermy or ultrasound diathermy.

Correct option is (a) cutting, coagulation, FULGURATION

For explanation I would say: Cutting happens when the heat is given is so high that the cell burns and is separated. This causes the incision to be formed, hence cutting. Coagulation happens when the cytoplasm is heated so MUCH that it boils and JOINS together. Fulguration is a PROCESS in which the heat is applied and a spread out action takes place. It COVERS a larger area.