Dosimetry Data Requested
Please send to me by fax (713-794-1364) or overnight express to the address listed below at your
earliest convenience, the following dosimetry data.
Radiological Physics Center
8060 EL RIO St.
Houston, TX 77054
I.
COMPLETED FORMS (blank forms attached are also available at http://rpc.mdanderson.org):
Along with the RPC forms for the following items, please include copies of the indicated documents.
Instrumentation:
Photons:
Electrons:
Brachytherapy:
II.
Calibration certificates (Ion chambers & Electrometers)
Most recent yearly output calibration (various factors & calculations)
Most recent yearly output calibration (various factors & calculations)
Source-strength certificates
Each PHOTON beam:
Generate plans from your treatment planning system (TPS) for a 45cm x 45cm x 45cm water
phantom. For each of the following setups, obtain MU and point-doses.
NOTE: Fax filled out Tables 1-5, and submit hard copies of the plans during the site-visit.
a) PDD & Output Factors: Generate plans to fill in Table 1.
b) Wedge Transmission: Generate plans to fill in Table 2, for the most clinically used wedges
(i.e. lower, upper, etc.)
c) Asym-Jaw calc: Generate plans to fill in Table 3 (see setup in section IV).
d) Profile data at dmax: Off center ratio (OCR) or in-air off-axis ratio (OAR) for the largest field
size and fill in Table 4. (Tabular).
e) Copies from dosimetry data book: Wedge/Tray factors, tables of %DD, TMR & Output factors.
f)
III.
Small field-size output factors: Generate plans to fill in Table 5. For Varian machines, use
MLC to generate these field sizes while maintaining the
secondary jaws at a 10 cm x 10 cm.
ELECTRONS (each energy & linac): Provide copies of the following.
a) Cone ratios (output factors) for nominal and extended SSDs
b) PDD (NOT ionization) for standard SSD & standard Cone Size: tabular data.
Include depth of output calib. (where clinical output is 1.000 cGy/mu)
c) Dose calculation technique for extended SSD = 110 cm
(if use VSD, please include table of VSD values)
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IV.
CALCULATIONS:
Please run the following point calculations, and the 4 reference cases (available at
http://rpc.mdanderson.org located under on-site audits).
1.
Asymmetric Jaws: (for all applicable beams)
Set a 10 cm x 10 cm field, 100 cm SSD, as a half-beam block using the asymmetric jaws. At 5
cm off-axis, calculate MU to deliver 1000 cGy to 15 cm depth, and determine doses at the
following points. (See Figure 1):
Off-axis 5 cm, depth 5 cm
depth 15 cm
Off-axis 2 cm, depth 5 cm
depth 15 cm
20 cm
10 cm
Blocked area
Asym Jaw as
½ beam block
Calculation points
2 cm
10
cm
5 cm
Figure 1. Setup for asymmetric jaw calculations.
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Table 1: Deliver 1000 cGy, 100 cm SSD, to 10 cm depth. Determine MU & point doses.
Field 
MU ? 
6x6
Depth (cm)
dmax
5
10
15
20
10x10
15x15
20x20
30x30
Fill in Point Doses (cGy) below for above field sizes
Table 2: Deliver 1000 cGy (wedged fields), 100 cm SSD, to depths & for field sizes listed below.
Determine MU.
Field
(cm x cm)
6x6
10 x 10
15 x 15
20 x 20
Depth
(cm)
5
10
15
10
Fill in MU for wedges
300
450
0
15
600
Table 3: For the asym-field, deliver 1000 cGy, 100 cm SSD, to 15 cm depth. Determine MU &
point doses.
Off-axis distance 
MU ? 
Depth (cm)
2 cm
5 cm
Fill in Point Doses (cGy) below at the
above off-axis distances
5
15
Table 4: Off Center Ratios (OCR) at dmax depth for a 40 cm x 40 cm field size.
Dist. Off axis 
OCR? 
5 cm
10 cm
15 cm
Table 5: Deliver 1000 cGy, 100 cm SSD, to 10 cm depth. Determine MU.
Field 
MU ? 
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1x1
2x2
3x3
4x4
6x6
10x10
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Benchmark Cases
The benchmark cases can be downloaded from the RPC’s website (http://rpc.mdanderson.org).
On the top bar there is a hot button labeled “on-site audits”. Under this you will find a link to the
benchmark cases. There are four cases; Brain, Breast, Cranial-Spinal and Mantle. Please plan all
4 cases following the directions which are posted on the website. Please submit all color hardcopy
data to the RPC:
Hannah Nguyen
Radiological Physics Center
8060 EL RIO St.
Houston, TX 77054
All electronic data is to be submitted to the ITC (http://atc.wustl.edu).
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