about 2D Vs 3D-CRT Comparison and process of the 3d-crt Basic treatment capabilities with minimal imaging support have been labelled as 2D RT (2D radiotherapy). With more advanced imaging and dose calculation capabilities for treatment planning, and more sophisticated treatment delivery procedures, 3D conformal radiotherapy (3D CRT) can be provided. Further sophistication in treatment planning and treatment delivery capabilities allow for intensity-modulated radiotherapy (IMRT). There are significant differences between conventional 2D RT treatment planning and delivery and 3D CRT. To establish 3D CRT in an institution a number of steps should be taken. This includes the definition of the scope of the programme, developing staffing needs, training of all personnel to be involved, acceptance testing and commissioning of the new equipment and the development and implementation of a comprehensive QA programme. IMRT techniques are significantly more complex than 3D CRT and require the close collaboration and expertise of an appropriately-trained multidisciplinary team, including radiation oncologists, medical physicists, and radiation technologists. Important Principles A complete understanding of all steps is necessary before one can successfully begin a new programme in 3D CRT. It is important to allow sufficient time for physics staff training prior to the arrival of the equipment so that trained staff are in place to carry out acceptance testing and commissioning. Only radiation oncology departments that have sufficient experience with 3D CRT are in a position to transition to IMRT. Adequate training in IMRT technology for all members of the team is essential prior to the initiation of such a programmer. Ideally, the team members are best trained on equipment that they plan to use for IMRT in their own department. Introduction to References IAEA-TECDOC-1588 is divided into two parts: 3D CRT and IMRT. It provides guidelines, and highlights the milestones that are to be achieved for the transition from 2D RT through 3D CRT to IMRT. The report is written as an extension to IAEA-TECDOC-1296 and should be consulted in conjunction with that report. The two journal articles describe in detail the transition from 3D CRT to IMRT. IAEA web page "Transitioning from 2-D Radiation Therapy to 3-D Conformal Radiation Therapy and Intensity Modulated Radiation Therapy" contains training material that has been developed for this purpose. Design and Implementation of a Radiotherapy Programmer: Clinical, Medical Physics, Radiation Protection and Safety Aspects, IAEA-TECDOC-1296, 1998 (IAEA) Transition from 2-D Radiotherapy to 3-D Conformal and Intensity Modulated Radiotherapy, TECDOC-1588, 2008 (IAEA) Guidance document on delivery, treatment planning, and clinical implementation of IMRT: Report of the IMRT Subcommittee of the AAPM Radiation Therapy Committee, 2003 Implementing IMRT in clinical practice: a joint document of the ASTRO and the AAPM, 2004 Training.

3. Conventional, or 2D radiation therapy, uses x-ray
films to guide and position radiation beams and was
widely used in the 1960s-70s. CT scans that provide
3-dimensional imaging are not used to plan this type
of treatment.

4. What is the treatment planning process
for conventional 2D radiation?
Treatment planning for conventional 2D radiation does not take a long
time.
Patients can usually start treatment quickly compared to other kinds of
radiation therapy that need more in-depth (and time-consuming)
planning.
A machine called a “fluoroscopic simulator” is often used to plan your
treatment.
This type of simulator uses x-rays to see bones that are used as
landmarks to find where the tumor is and where to position the radiation
beams to treat the tumor.
The tumor volume and critical structures are drawn on 2D x-ray films and
used for treatment planning.

7. When is conventional 2D radiation
used?
This type of treatment is often used for urgent treatments.
Often, treatment can start the same day.
How is the beam shaped?
Shaping the beam in conventional 2D radiation therapy is difficult.
Instead, a few (2-4) simple square or rectangular beams are often used.
An example of a standard beam arrangement is opposed lateral beams
or a four-field box. Often this leads to a higher dose being given to the
normal tissue causing more treatment side effects.

8. Is conventional 2D radiation right now?
There are many types of radiation therapy.
Conventional 2D radiation is not used as often as it was many years ago
due to advances in treatment technology.
It does however provide a treatment option when radiation is needed
quickly.

9. What are the disadvantages of conventional
2D radiation?
The disadvantages of 2D therapy are:
2D planning for a 3D tumor.
Large treatment fields with higher radiation doses to normal tissue.
More side effects.
Custom blocks that can be used for some beam shaping need a lot of work
and are timely.
What are the advantages of conventional 2D
radiation?
The advantages of 2D therapy are:
Treatment planning is quick.
Patients can start treatment fast, sometimes on the same day.

10. Three-dimensional (3D)
Conformal Radiation Therapy
Three-dimensional conformal radiation, also called 3D conformal
radiotherapy or 3D-CRT, became widely used in the 1970s-80s.
This was a result of advances made in imaging technologies.
CT-guided therapy allows the tumor and normal organs shape and size to
be defined in three dimensions.
Instead of using a "flat" image of an x-ray that only shows the tumor's
height and width, which is used for conventional 2D radiation therapy.

11. What is the treatment planning process for 3D Conformal Radiation
Therapy?
You will need to have a simulation done with you in the treatment
position. 3D imaging will be taken to allow for the best treatment
planning.
After imaging is done, the tumor is outlined in three dimensions. Normal
organs that are found near the tumor and need to be avoided are also
outlined in 3D .
Beams are then arranged to avoid healthy tissue while giving a specific
dose of radiation to the tumor.
Special computer software is used to see the amount of radiation the
tumor and normal tissues will receive to make sure that all parts of the
tumor are getting the correct dose.
The beams are shaped and aimed at the tumor from many directions.
Using several beams, as opposed to a few beams, helps reduce the damage
to the normal tissues.

12. How is the beam shaped?
Beams are shaped to avoid treating healthy tissue. There are two ways of
shaping the beam:
Cerrobend blocks: Custom blocks that are molded into a specific shape.
Multileaf collimators (MLCs): Uses “leaves" within the machine that can be
used to form precise beam shapes. The leaves are skinny metal blocks,
which move quickly to form different, complex patterns . These leaves are
also an important part of Intensity-Modulated Radiation Therapy (IMRT).

14. When is 3D Conformal Radiation Therapy
used?
3D conformal radiation is typically used on tumors that are oddly shaped
and are close to healthy tissues and organs. Compared to 2D conventional
radiation, 3D conformal radiation allows your radiation oncologist to limit
the amount of radiation to nearby healthy tissue. It is commonly used in
the treatment of:
Brain cancer.
Head and neck cancer.
Liver cancer.
Lung cancer.
Prostate cancer.

15. What are the possible side effects?
Some people do not have any side effects. However, if you do have side
effects, they are related to the area that is being treated. Some common
side effects are:
Fatigue.
Skin reactions.
Hair loss.
Nausea.