????? ?????? ???????? Clinical Radiation Generator - PowerPoint PPT Presentation

Loading...

PPT – ????? ?????? ???????? Clinical Radiation Generator PowerPoint presentation | free to download - id: 74fb40-N2MxN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

????? ?????? ???????? Clinical Radiation Generator

Description:

Clinical Radiation Generator ... spinal cord) Largely replaced by other treatment modalities Kilovoltage Equipment ... Introduction To Medical Physics Author: ITC\ACS ... – PowerPoint PPT presentation

Number of Views:266
Avg rating:3.0/5.0
Slides: 26
Provided by: ITCA6
Learn more at: http://medicalphys.files.wordpress.com
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: ????? ?????? ???????? Clinical Radiation Generator


1
????? ?????? ????????Clinical Radiation Generator
  • ??????
  •  ?. ???? ???? ???????

2
???????? ????????? Radiotherapy
??????? ??????? ?????? ?? ?????? ??????? Using
the ionizing Radiation to treat cancer
?????? ?????? (?? ???) External Beam Therapy
(EBT)
?????? ?????? (?? ???) Brachytherapy
3
Radiotherapy
  • One of the main treatment modalities for cancer
    (often in combination with chemotherapy and
    surgery)
  • It is generally assumed that 50 to 60 of cancer
    patients will benefit from radiotherapy
  • Minor role in other diseases

Siemens Oncology
4
External Beam Radiotherapy
Beam 2
Beam 3
Beam 1
tumor
patient
5
(No Transcript)
6
External Beam Radiotherapy
  • More than 90 of all radiotherapy patients are
    treated using EBT
  • Most of these are treated using X-rays ranging
    from 20keV to 20MeV in peak-energy
  • Other EBT treatment options include telecurie
    units (60-Co and 137-Cs), electrons from linear
    accelerators and accelerators for heavy charged
    particles such as protons

7
Cancer incidence (WHO)
8
Major indications for radiotherapy
  • Head and neck cancers
  • Gynaecological cancers (eg. Cervix)
  • Prostate cancer
  • Other pelvic malignancies (rectum, bladder)
  • Adjuvant breast treatment
  • Brain cancers
  • Palliation

9
Approaches
  • Palliative radiotherapy to reduce pain and
    address acute symptoms - eg bone metastasis,
    spinal cord compression, ...
  • Radical radiotherapy as primary modality for cure
    - eg head and neck
  • Adjuvant treatment in conjunction with surgery -
    eg breast cancer

10
Aim
Patient
Critical organs
  • To kill ALL viable cancer cells
  • To deliver as much dose as possible to the target
    while minimising the dose to surrounding healthy
    tissues

target
Beam directions
11
Prognostic Factors
  • Cancer type and stage
  • Patient performance
  • Radiation dose
  • ...

Good prognosis
survival
Bad prognosis
time
12
Prognostic Factors
  • Cancer type and stage
  • Patient performance
  • Radiation dose
  • ...

Accurate dose delivery matters!
13
Dose should be accurate
  • To target
  • 5 too low - may result in clinically detectable
    reduction in tumour control (eg. Head and neck
    cancer 15)
  • To normal tissues
  • 5 too high - significant increase in normal
    tissue complication probability morbidity
    unacceptable side effects

14
External beam radiotherapy (EBT) treatment
approaches
  • Superficial X-rays
  • Orthovoltage X-rays
  • Telecurie units
  • Megavoltage X-rays
  • Electrons
  • Heavy charged particles
  • Others

15
External beam radiotherapy (EBT) treatment
approaches
  • Superficial X-rays
  • Orthovoltage X-rays
  • Telecurie units
  • Megavoltage X-rays
  • Electrons
  • Heavy charged particles
  • Others
  • 40 to 120kVp
  • 150 to 400kVp
  • 137-Cs and 60-Co
  • Linear accelerators
  • Linear accelerators
  • Protons from cyclotron, C, Ar, ...
  • Neutrons, pions

16
Superficial radiotherapy
  • 50 to 120kVp - similar to diagnostic X-ray
    qualities
  • Low penetration
  • Limited to skin lesions treated with single beam
  • Typically small field sizes
  • Applicators required to collimate beam on
    patients skin
  • Short distance between X-ray focus and skin

17
Superficial radiotherapy
Philips RT 100
18
Superficial radiotherapy issues
  • Due to short FSD high output and large influence
    of inverse square law
  • Calibration difficult (strong dose gradient,
    electron contamination)
  • Dose determined by a timer - on/off effects must
    be considered
  • Photon beams may be contaminated with electrons
    from the applicator

19
Orthovoltage radiotherapy
  • 150 - 400kVp
  • Penetration sufficient for palliative treatment
    of bone lesions relatively close to the surface
    (ribs, spinal cord)
  • Largely replaced by other treatment modalities

20
(No Transcript)
21
(No Transcript)
22
Kilovoltage Equipment (150 - 400 kVp)
  • Depth dose dramatically affected by the FSD

FSD 6cm, HVL 6.8mm Cu
FSD 30cm, HVL 4.4mm Cu
23
Orthovoltage patient set-up
  • Like for superficial irradiation units the beam
    is set-up with cones directly on the patients
    skin

24
Megavoltage radiotherapy
  • 60-Cobalt (energy 1.25MeV)
  • Linear accelerators (4 to 25MVp)
  • Skin sparing in photon beams
  • Typical focus to skin distance 80 to 100cm
  • Isocentrically mounted

25
?? ???? ????????
About PowerShow.com