Principles of Treatment Planning

Question 1

process whereby the therapeutic strategy is realized as a set of treatment instructions together with physical description of the distribution of dose in patient

Answer 1

Treatment Planning

Question 2

Aims of treatment planning

Answer 2

• To localize the tumor volume in the patient and to define the target volume for treatment
• To measure the outline of the patient and to place within it the target volume and other anatomical structures…
• to determine the optimum treatment configuration required to irradiate the target volume to the specific dose within particular clinical constraints
• to calculate the resultant dose distribution in the px
• to prepare an unambiguous set of treatment instruction for the RT

Question 3

can be defined as the determination of the various beam parameters that will produce a dose distribution such that the target volume will receive the required lethal radiation dose without producing any patient morbidity

Answer 3

Optimization of external beam treatment planning

Question 4

Various beam parameters

Answer 4

field size
gantry
collimator angulation
mlc shapes

Question 5

MLC means

Answer 5

Multileaf Collimator

Question 6

optimum treatment plan should meet several main criteria:

Answer 6

• the dose throughout the tumor volume should be uniform as possible and should deliver the prescribed dose to a specific part
• the dose outside the treatment volume should be as low as possible and the dose to the critical organs should be kept below an acceptable level

Question 7

Strategies applied

Answer 7

• use fields of appropriate size
• increase the number of fields
• select appropriate beam direction
• adjust beam weights
• use appropriate beam energy
• use beam modifiers such as wedge filters and compensators

Question 8

critical in the success of treatment process

Answer 8

patient positioning

Question 9

if stable position cannot be maintained and reproduce daily, the result is

Answer 9

either geometric miss of target volume or irradiation of greater amount of uninvolved normal tissues

Question 10

used to achieve true reproducibility of the treatment and accuracy in set-up

Answer 10

Immobilization device

Question 11

requirements of good immobilization devices

Answer 11

• rigid and durable enough to withstand an entire course of treatment
• take into consideration the patients condition and treatment unit limitations

Question 12

designed to place patient in a particular position for treatment.

Answer 12

Positioning aids

Question 13

examples of Positioning aids

Answer 13

dog dish head holders, head and neck support, sponge pillows, foam cushions, sandbags, arm boards

Question 14

Used in addition to Positioning aids. They usually provide some restrictions of movement and stability of treatment position in cooperative patients

Answer 14

Simple immobilization devices

Question 15

example of Simple immobilization devices

Answer 15

masking tape, large rubber bands, safety belts, head frame with bite block, foot strap

Question 16

individualized immobilizers that restrict patient movement and ensure reproducibility in positioning

Answer 16

Complex immobilization devices

Question 17

Complex immobilization devices is usually made of

Answer 17

plaster, plastic, or styrofoam

Question 18

example of Complex immobilization devices

Answer 18

light cast, alpha cradle, aquaplas

Question 19

these devices allow unusual px positions and portal markings on the device could be made, thus alleviating the need for patients skin markings

Answer 19

Complex immobilization devices