Hand Calcs Part 1

TFD stand for

Target to Film Distance

What does a mag factor of 1.4 mean?

What is the TFD?

The image on film is 140% as large as the actual size of the object

Or The image on film is 40% larger than it is in real life

TFD= 140cm

True or False: The Calc sheets for all facilities are all the same.

False. The Calc sheet used at other facilities will all look different.

BUT! All will have the same basic essential characteristic.

3b. What does TPR stand for?

3b. Tumor-Phantom Ratio

What is a Smooth Mover

A transfer device. If patient is on a stretcher/ gurney for picking them up. \

Used in PA field ONLY

What is a Slotted Tray?

Used for hand blocks.

What does a .9 ISCF mean?

.9 Isodose Curve Factor

You are treating to 90% isodose line

1. Problem

2. Solutions

   We plan on giving 180cGy to the tumor

1. Problem! Not all parts of the tumor is getting 100% dose (180cGy). How do we solve this problem?

   Solution:

   ↑f.s = ↑ innermost box. So it encompasses all the tumor. The problem with making ↑ f.s. = ↑ normal tissue treated = ↑ side effects

   Instead of treating to 100% dose line, treat to 90%.

   i.e. Give 180cGy to 90% isodose curve.

Bigger Field Size = (more/less) Output

More Output (# of rays)

What is in the (1)x-axis & (2) y-axisof the TPR tables

x-axis: Tmt. Eq. Sq. Field Size

y-axis: Depth of tumor

Interpolation Formula

[(High # - Low #) * %] + Low #

Equivalent Square Formula

L = Length

W = Width

How to calculate the area of:

1. Square/ Rectangle

2. Triangle

3. Circle

1. L x W

2. ½ B x H (highest # is hypothenuse→ ignore it)

3. π x r²

The following are used to figure out:

1. Collim. Eq. Sq. Field Size

2. Tmt, Eq. Sq. Field Size

1. in-air output factor

2. TPR

calculate the collimator equivalent square area field size and the treatment equivalent square field size for the following:

Field size= 15 x 22, there is a 2 x 8 rectangular block and 4 x 6 x 6 triangular block and a circular block with a diameter of 4cm.

Coll eq sq= 15x22x2/15+22=17.82

Tmt eq sq= (15×22 = 330) -16 (rectangle) – 12 (triangle) – 12.56 (circle*)= 289.44, then square root= 17.02