Helpful Equations to Study
Checklist for Equations & Numbers & Relations
1. Ci:
2. mCi:
3. Exposure:
4. Absorbed Dose:
5. 1 Gray =:
6. Dose Equivalent:
7. 1 Sv =:
8. Alpha Decay:
9. B-Decay:
10. B+ Decay:
11. Ebeta:
12. Activity Equation:
14. Decay constant:
15. Isotope Half Life
3.7 x 10^10 dps (Bq)
3.7 x 10^7 dps (Bq)
Roentgen
Rad, Gray
100 Rad
Rem, Sv
100 Rem
A-4, Z-2
A, Z+1
A, Z-1
Avg = 1/3 Emax
Ao = A e- λ t
λ = 0.693 / T1 / 2
Half Life
Pd – 103:
I-125
Ir-192
Co-60
Cs-137
Ra-226
17 days
60 days
74 days
5.3 yrs
30 yrs
1600 yrs
16. Isotope Energy
Energy
Pd-103
I-125
Ir-192
Co-60
Cs-137
Ra-226
Sr-90/Y-90
21 keV
27keV
380 keV
1.25 MeV avg
662 keV
883 keV
2.2 MeV Beta
17. Secular Equilibrium
18. Transient Equilibrium
Tp>>>>Td up <<<<<ud
Tp>Td up <ud
19. PE
20. CS
21. PP
22. CS photon at 90 degrees
23. CS photon at 180 degrees
24. Attenuation equation
25. Half Value Layer
Z^3, 50 keV
Inde, 30 keV – 30 MeV
Z^2, >1.022 meV
511 keV
250 keV
I – Io e-ut
U = 0.693 / HVL
26. Graph
Graph
Act vs time
Act vs time
I vs thickness
I vs thickness
Linear
Semi – Log
Linear
Semi-Log
27. X-ray production (diag) vs mAs
28. X-ray production (diag) vs kVp
29. Thoraceus filter order:
30. Superficial E range
31. Orthovoltage Range
32. BJR 17 requires:
33. Co-60 Unit dose rate:
34. Co-60 Leakage:
35. Co-60 source size
36. Linac focal spot size:
Proportional to mAs
Proportional to kVp^2
Tin-Copper-Aluminum
50-150 kVp
150-500 kVp
HVL & SSD
240 cGy/min
10 mR/hr max, 2 mR/hr avg
1.5-2.0 cm
0.5-3mm
37. Transmission Thru:
Percentage
Jaw
MLC
Intraleaf MLC
Cerrobend
1%
2%
4%
3.5%-5%
38. Equivalent Square Question:
39. PDD
40. MF
4A/P
Dd/Ddmax at SSD
See notes
41. Energy and dmax
Depth
250 keV
1.25 MeV
4 MV X
6 MV X
10 MV X
18 MV X
Surface
0.5
1.0
1.5
2.5
3.5
6 MeV electron
9 MeV electron
12 MeV electron
1.2
2.0
2.5
42. TAR
43. BSF
44. TMR
45. TPR
Dd/Dfs at SAD
Dmax / Dfs at SAD
Dd / Ddmax at SAD
Dd / Dref at SAD
46. BSF largest for:
47. WF
48. 1.0 cm Pb =
49. Wedge angle defined:
50. Hinge Angle formula
51. Penumbra Equation:
52. Penumbra Co-60
53. Penumbra Accelerator
54. Contralateral Breast
55. Pacemakers Limit
56. TBI Rx dose
57. TBI dose rate
58. IORT single fx dose
59. Stereotactic Gamma Knife
accuracy
60. Sterotactic Linac accuracy
61. Electron Max Range
62. Electron d80
63. MU equation SSD
64. MU equation SAD
65. Dose to other point SSD
66. Dose to other point SAD
67. Gaps
68. Coll Rotation, Table
69. Electron MU
70. Brachy Exposure
71. Exposure Rate Constant Ra-226
72. Ra-226 to Cs-137 conversion
73. Cumulative Dose Brachy
74. CT Number Water
75. CT Number Bone
76. CT Fat
77. CT Lung
78. CT Air
(dref = 5cm for 6X; 7cm for 18X)
0.7 mm Cu HVL Ortho
Output w wedge / Output w/o wedge
1.2 cm cerrobend
50% angle isodose with normal
WA = 90 – Hinge Angle / 2
WA = (180 – Hinge Angle) / 2
P – s(SSD + d – SCD) / SCD
15 mm
8 mm
200 rad
200 rad
1000-1200 cGy
5-10 cGy/min
100-2000 cGy
0.3 mm
1.0 mm
E/2
E/3
See notes
See notes
See notes
See notes
Gap = FS/2 * (d/SAD)
Tan angle = 0.5*L / SSD
See notes
X = A * Γ / d^2
8.25 R-cm^2 / mg-hr
10 mg Ra = 25 mCi Cs-137
Dose = 1.44 T½/2 * initial dose rate
0
1000
-100
-400
-1000
79. Best DRRs
80. CT accuracy
81. MRI accuracy
82. Air Kerma units:
83. Pt A Dose gyn LDR
84. Pt B Dose
85. I-131 Therapy Dose
86. I-131 radiation and T½
87. Prostate seed I-125 dose rate:
88. Prostate seed Pd-103 dose rate:
89. LDR dose rate
90. MDR dose rate
91. HDR dose rate
92. HDR unit source
93. HDR source positioning accuracy
94. Vascular brachy Rx dose
95. Vascular brachy Rx pt
Thinnest slice, smallest skip
1 mm
2 mm
uGy-m^2/ hr
50 – 60 cGy/hr
Pt A dose / 3
> 30 mCi
Beta decay / 8.05 day
5 – 10 cGy / hr
20-30 cGy / hr
40 -200 rad / hr
200 -1200 rad / hr
>1200 rad / hr
10 Ci Ir-192
1 mm
15-20 Gy
2 mm
96. PDD
Drawings
6 MV X
18 MV X
6E
18 E
250 MeV Proton
Orthovoltage 250 k Vp
Co-60
97. Isodose Curves
Drawings
6E
18E
6X open
6X 45 degree wedge
6X thru bone
6X thru lung
6X anterior partial arc (330 – 30)
6X bilateral prostate arc
6X full 360 arc
Brachy tandem and ovoid
Brachy Prostate seed
98. LD 50.30 (old)
99. LD 50/60 (new)
100. dVh Y axis
450 rad
350 rad
Volume
101. dVh X axis
Dose
102. Organ
Tolerance (cGy)
Ovary
Testis
Cataracts
Kidney
Liver
Spinal Cord
Heart
300
200
500
2000
2500
4500
4500
103. Radiatoin Exposure Limits
Limit
Whole Body
Organ
Fetus
Public
Public
5 Rem
50 Rem
500 mRem
100 mRem
<2 mR/hr
104. Film Badge if:
105. Thyroid ablation release
106. SS Inventory
107. SS Wipe Test
108. SS Wipe Test Results
109. Misadministration
110. Recordable Event
>10% of limit or high rad area
< 5 mR/hr or 30 mCi
3 months
6 months
< 0.005 uCi
>20%, patient, site, isotope, remove,
leaking, call NRC
>10%, no script, internal report
111. Shielding Parameters
Parameter
P
W
U
T
Permissible level
Workload
Use Factor
Occupancy Factor
112. Neutrons produced by linacs
114. Neutrons shielding problems
115. Monthly linac output
116. Monthly flatness
117. Monthly symmetry
118. Co-60 timer error
119. Gantry / collimator
120. Mechanical
121. Rad / Light
>10 MV X
> 15 MV S
2%
3% of 80% field at d10
2% of 80% field at d10
0.02 minute
1 degree
2 mm
2 mm
122. Equipment calibratn equipment
123. Temp-Pressure correction
124. Calibration Protocols (new)
125. Calibration Protocols (old)
126, QA Protocol
Prior to use, repair, 2 yrs by ADCL
(273 + 7)/295 * 760/P
TG-51
TG-21
TG-40