Treatment Planning

Exam Approach

What is all about Radiation Oncology?

  • There should be an standardized approach to Treatment Planning.
  • When someone ask you, HOW DO YOU TREAT THIS PATIENT? They are looking for a definite structured answer
  • Here is a reasonable approach to any site:
  • Medical Indications of RADIATION in management of Cancer
  • Goal of treatment is EITHER
  • RT is administered either as
    • Neoadjuvent
      • Increase the chance of resectability
      • Better oxygenation
      • Easier to define the target
      • Increase the chance of clear margin
      • Examples
        • Pancreas
        • Rectum
        • Esophagus (?)
        • Sarcoma
    • Radical Treatment as mainstay of treatment ( No surgery )
      • Prostate
      • Lung Ca Early Stage
      • Cervical Cancer
      • Head and Neck
      • Skin
    • Adjuvant
      • to decrease the chance of recurrence
      • For positive margins ( one clear indication )
      • Less fibrosis during surgery
      • Examples
        • Breast
        • Endometrium/ Cervix
        • Lung
        • Brain tumor
  1. So Make the Indication and Goal clear in your mind
    • This requires that you read and study that topic.
    • Understand the nature of the cancer growth and metastasis
      • Local
      • Regional
      • Distant
    • This is all medicine :)

I know you are excited to use your knowledge and experience to treat the patient.
BUT Think about the contraindication of radiation before offering any radiation :

  • Inflammatory Bowel Dis.
  • CVD —> Scleroderma
  • Pregnancy
  • Previous Radiation( relative )

* So! Think about, how I REALLY will treat that patient?

  • We are not surgeons so that we go to OR or RT room and deliver the treatment directly to the patient.
  • TREATING a patient with Radiation requires PLANNING ahead of time
  • Treatment happens on patient
  • Planning (most of the time) happens on an image.
  • That image
    • Can be a film
      • Conventional Simulation
    • Can be a CT
      • 3DCRT
    • Sometimes we directly plan on patient's body
      • Clinical mark-up
    • Can be an MRI
    • Use a PET study fused

The image basically should SIMULATE the patient so that you can use your PLAN to TREAT the patient.
When think about SIMULATION;

  1. Think what is the image that I will use for simulation
    • That's easy because options are limited and it's usually CT these days!
    • It's nice to know or mention where do we get the image from
      • I will use a plain X-Ray of the arm for planning
      • I will ask for CT Scan Pelvis from L3-L4 to to ischial tuberosity
  2. Think what is the position of the patient so that I will be able to deliver the Rad to the volume
    • Prone/Supine
    • Arms at side/ on the chest/ up and abducted
    • Chin extended
  3. Do I need any DEVICE which is useful for this specific positioning
    • boards
      • breast board
      • lung board
      • head shell
      • breast shell
  4. Is there any form of PREPARATION that patient need?
  • Basically preparation is use of patient's own organs to help us delivering a better/less toxic plan.
    • Bladder Full (prostate; rectum); Empty (Bladder Ca)
    • Bowel preparation
    • Any contrast right before imagining?

Now you know how you have position the patient. Also you know what kind of order you should put for therapist to consider whilst positioning the patient

5. Then think what kind of MODALITY you will use to treat patient? Options are:

  • Photon
    • Think about energy
      • 6-18MeV
        • to be able to decide you need to know Maximum Depth Dose of each energy
      • Orthovoltage
  • Electron
    • You should be able to decide roughly about energy
    • You need to know field effects
      • at surface —> bulging of isodose
    • Effect of energy
      • Know the D90 depth
      • Know the range of electron based on energy

6. Simplest thing people/other professional may ask you is that how much ( DOSE/FRACTIONATION ) you will give?

  • It's a simple thing and you probabely never forget to mention
    • Remember if you treat the patient in two phases; you can mention it here.
  • Be ready to be asked about BED :)
    • Know the formula
    • Know the effect of fractionation
    • Know why we do fractionate the dose instead of giving it all in one session
      • Quick answer is to give chance for cells to repair

7. Now is the time to mention with all these setup and so on, what ( what VOLUME ) you are going to treat:

  • GTV
  • CTV
  • PTV
    • This one is easy and basically is a margin
      • 1cm for Pelvis
      • 1cm for Abdomen
      • 0.5cm for Head and Neck ( as using shell ; IGRT )
      • For palliative treatment —> 0.5-1cm
    • 0.5cm off from skin —> modified PTV

8. Well, you are treating a patient. Not unreasonable to be aware of about side effects. So know the ORGANS AT RISK.

  • When you mention an organ ; you should be aware of the dose constraint
    • This means you should know side effect ( end point )
    • Also you should know the probability ( TD 5/5 and TD 5/50 )

9. The last part is OUTCOME of your treatment.