Posted by Dr Santam Chakraborty at 11:41 AM
A blog describing some of the more obscure and older techniques used in Radiation Oncology
Haagensen's Grave signs are a group of signs that when present in patients of carcinoma breast indicate inoperability.
These signs were identified by Haagensen and Stout in a review of the clinical features of patients of breast cancer treated at their hospital in the 1940s. Presence of these signs were associated with a 0% probablity of 5 year cure and 50% risk of local recurrence.
The grave signs as given by the duo include:
|Stage A||No skin edema, ulceration, or solid fixation of the tumor to the chest wall. Axillary nodes are not involved clinically|
|Stage B||No skin edema, ulceration, or solid fixation of the tumor to the chest wall. Clinically involved nodes, but less than 2.5 cm in transverse diameter and not fixed to overlying skin or deeper structures of the axilla|
|Stage C||Any one of the five grave signs of advanced breast carcinoma:|
|(1) Edema of the skin of limited extent (involving less than one-third of the skin over the breast)|
|(2) Skin ulceration|
|(3) Solid fixation of the tumor to the chest wall|
|(4) Massive involvement of axillary lymph nodes (measuring 2.5 cm or more in transverse diameter)|
|(5) Fixation of the axillary nodes to overlying skin or deeper structures of the axilla|
|Stage D||All other patients with more advanced breast carcinoma, including:|
|(1) A combination of any two or more of the five grave signs listed under stage C|
|(2) Extensive edema of the skin (involving more than one-third of the skin over the breast)|
|(3) Satellite skin nodules|
|(4) The inflammatory type of carcinoma|
|(5) Clinically involved supraclavicular lymph nodes|
|(6) Internal mammary metastases as evidenced by a parasternal tumor|
|(7) Edema of the arm|
|(8) Distant metastases|
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Carcinoid syndrome is the most common systemic syndrome caused by carcinoid Tumors. The syndrome describes a symptom complex resulting from the secretion various bioactive amines secreted by carcinoid tumors. In addition to carcinoid syndrome other bioactive substances may also be secreted by the tumor especially in case of foregut carcinoids.
Oberndorfer introduced the term carcinoid in 1907 to describe tumors that behaved more indolently than adenocarcinomas. These are composed of monotonous sheets of small round cells with uniform nuclei and cytoplasm. They are neuroendocrine tumors and share certain common features with other NETs:
Posted by Dr Santam Chakraborty at 12:02 PM
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Posted by Dr Santam Chakraborty at 9:15 PM
Posted by Dr Santam Chakraborty at 4:49 AM
High-frequency alternating current applied via an electrode(s) placed within the tissue generates ionic agitation as the ions attempt to change directions and follow the alternating current, thereby creating localised friction heat.
Uses heat generated from ionic agitation inside the tissues after application of a RF current.
The heat produces a rim of necrosis around a RFA needle.
Tumors less than 3 cm size
Away from the hepatic hilum
Deep seated tumors
Tumors with major vessel invasion
Tumors situated peripherally or near portal tracts
Localized breast cancers as an attempt for BCS
Tumors which are unresectable
Primarily in colorectal CA mets 1 - 3 in number
Contains several needles which when extruded assume an umbrella like configuration
Uses 400 - 500 KHz AC current
Can produce a zone of necrosis with a diameter of 7 cm
Generates RFA current between 400 - 500 KHz
Imaging of the tumor to determine extent
Sedation and analgesia
Probe insertion under LA / GA
deployment of needles
Application of RFA energy
Removal while sealing the tract with heat
Allow an electrical circuit to form with patient and the RFA needle
Cant be used for larger or multiple tumors
Regional failure can occur
Cant be used for tumors close to major vessels or nerves
Requires special imaging guidance and planning
Expense of needle
Minimally invasive procedure - can be done percutaneously
Time 20 - 30 min
Good control of the necrosis area
Can be repeated multiple times
Posted by Dr Santam Chakraborty at 8:42 AM
Definition: It is a device that uses high frequency electromagnetic waves to accelerate charged particles, such as electrons to high energies through a linear tube.
Types of linear accelerator design:
In the latter design there is a dummy load, which absorbs the excess power and prevents a reflected wave. In the standing wave design, there is reflection of the waves at both the ends of the structure, so that combinations of forward and reverse directed waves give rise to a standing wave design.
Whether standing or traveling wave design linear accelerators used in medical purposes, accelerate electrons along electromagnetic waves or frequency in the microwave region that is around 3000 Hz.
Components of a linear accelerator:
1. The Magnetron
2. The Klystron
3. Accelerator tube
4. Gantry & treatment head:
a. Transmission target
b. Flattening filter, and scattering foil.
c. Dose monitoring chambers.
1. Primary collimator.
2. Secondary collimators
3. Multileaf collimators.
The first medical linear accelerator was installed in the
Description of each component:
i. Dose rate
ii. Integrated dose
iii. Field symmetry.
i. Primary Collimators: Where the beam is shaped into the useful size and unwanted photons are removed.
ii. Secondary Collimators: Allow customized shaping of the beam by two pairs of movable lead blocs which move in a fashion such that the edge is always parallel to the beam. The maximum field size is 40 x 40 cm when projected at the isocenter.
iii. Multileaf collimators.
iv. Electron Collimators: Are special devices called electron cones used to generate the electron field shape. These are usually attached to the machine externally.
Posted by Dr Santam Chakraborty at 7:09 PM