06 - A System of Dosimetric Calculations

06 - A System of Dosimetric Calculations - Lecture # 6 (Ch....

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
1 A System of Dosimetric Calculations Tarun K. Podder, PhD, DABR Department of Radiation Oncology Brody School of Medicine Leo Jenkins Cancer Center East Carolina University January 27, 2011 Lecture # 6 (Ch. 10)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Absorbed Dose Calculations Limitations of PDD and TAR methods of calculations: PDD depends on SSD – unsuitable for isocentric technique - TAR and SAR can be used Measurements of TAR/ SAR for MV beams are questionable - measurement in free-space/ air - chamber build-up cap (large, material properties, etc. .)
Background image of page 2
3 Dose Calculation Parameters Percentage Depth Dose (PDD) Collimator Scatter Factor (S c ) Phantom Scatter Factor (S p ) Tissue-Phantom Ratio (TPR) Tissue-Maximum Ratio (TMR) Total Scatter Factor, S c,p ( r ) = S p ( r ) x S c ( r )
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Collimator Scatter Factor (S c ) S c is also called as “output factor” Output in air for a given field Output in air for a reference field (e.g. 10 x 10) S c = Normally S c is measured at SAD distance on central axis.
Background image of page 4
5 Phantom Scatter Factor (S p ) Dose rate (output) in phantom for a given field at a reference depth (e.g. d max ) Dose rate (output) in phantom for the same depth for the ref. field with same collimator opening S p = S p (r) = S c (r ) S c,p (r ) S c,p (r ) = total scatter factor = Dose rate at a ref. depth for a given field size r Dose rate at the same point for a ref. field (e.g. 10 x10)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Scatter Factors
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/21/2012 for the course PHYS 6720 taught by Professor Hu during the Spring '10 term at East Carolina University .

Page1 / 30

06 - A System of Dosimetric Calculations - Lecture # 6 (Ch....

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online