Calibration (TG-51/TRS-398)#

Overview#

The calibration module actually consists of two submodules: tg51 and trs398, each addressing their respective protocol. Both modules contain functions and classes for calculation the protocol dose. The modules have some overlap, especially with basic functions as well as helper functions. The modules have tried to use the vocabulary of the respective protocol, but occasionally there are differences when we felt that using the same name was clearer. See the vocabulary section for full definitions.

Note

Besides the typical calculations one would expect, the modules also include helper functions, such as a PDD to TPR converter so that a TG-51 calculation can determine kQ from TPR and avoid the tedious PDDx. Additionally, pressure unit converters exist to go from the various units of pressure to kPa which is what pylinac uses.

Vocabulary that may be different than the protocol#

  • voltage_reference: Used in both TG-51 and TRS-398 for the voltage used when taking a reference reading; commonly -300V.

  • voltage_reduced: Use in both TG-51 and TRS-398 for the lower voltage used to determine ks/Pion; commonly -150V.

  • m_reference: The ion chamber reading at the reference voltage.

  • m_reduced: The ion chamber reading at the reduced voltage.

  • m_opposite: The ion chamber reading at the opposite polarity of the reference voltage: commonly +300V.

Vocabulary not listed here should be the same as the respective protocol.

Changing a bound#

Bounds are placed in the module to prevent catastrophic errors from passing in the wrong values; e.g. the wrong units. If you live in a place that has extreme temperatures or pressures or just otherwise want to change the default bounds, you can change the default range of acceptable values. E.g. to change the minimum allowable temperature that can be passed:

from pylinac import tg51

tg51.p_tp(temp=5, press=100)  # will raise bounds error

# override
tg51.MIN_TEMP = 0

tg51.p_tp(temp=5, press=100)  # no bounds error will be raised

You can override the min/max of temp, pressure, p ion, p elec, p tp, p pol. These bounds are the same for TRS-398. I.e. setting these in either module will set them for both modules.

TG-51#

Equation Definitions#

Equation definitions are as follows:

  • Ptp (Temp/Pressure correction) - TG-51 Eqn. 10:

    \[\frac{273.2+T}{273.2+22} * \frac{101.33}{P}\]

    Warning

    Temperature is in Celsius and pressure is in kPa. Use the helper functions fahrenheit2celsius(), mmHg2kPa(), and mbar2kPa() as needed.

  • Ppol (Polarity correction) - Rather than using TG-51 Eqn. 9, we opt instead for TRS-398 Eqn xx, which uses the absolute values of the positive and negative voltages. This is the same results as Eqn. 9 but without worrying about signs.:

    \[\frac{|M^+_{raw}|+|M^-_{raw}|}{2*M_{raw}}\]

  • Pion (Ion collection correction; only for pulsed beams) - TG-51 Eqn. 12:

    \[\frac{1-\frac{V_{H}}{V_{L}}}{\frac{M^H_{raw}}{M^L_{raw}} - \frac{V_{H}}{V_{L}}}\]

  • Dref (Reference electron depth; cm) - TG-51 Eqn. 18:

    \[0.6*R_{50} - 0.1\]

  • R50 (Beam quality specifier; 50% dose depth; cm) - TG-51 Eqn. 16 & 17:

    \[\begin{split}\begin{cases} 1.029*I_{50}-0.06 (cm) & 2\leq I_{50}\leq 10 \\ 1.059*I_{50}-0.37 (cm) & I_{50}\gt 10 \\ \end{cases}\end{split}\]

  • k’R50 (k’R50 for cylindrical chambers) - TG-51 Eqn. 19:

    \[0.9905+0.0710e^\frac{-R_{50}}{3.67}\]

  • PQ_gr (PQ gradient correction for cylindrical chambers) - TG-51 Eqn. 21:

    \[\frac{M_{raw}(d_{ref}+0.5*r_{cav})}{M_{raw}*d_{ref}}\]

  • PDDx (PDD from photons only) - TG-51 Eqns. 13, 14 & 15:

    \[\begin{split}\begin{cases} PDD(10) & energy < 10 \\ PDD(10) & no lead, energy >= 10, PDD(10) <75 \\ 1.267*PDD(10)-20.0 & no lead, 75\leq PDD(10)\leq 89 \\ PDD(10)_{Pb} & lead@50cm, PDD(10)_{Pb} < 73 \\ (0.8905+0.00150*PDD(10)_{Pb})*PDD(10)_{Pb} & lead@50cm, PDD(10)_{Pb} \geq 73 \\ PDD(10)_{Pb} & lead@30cm, PDD(10)_{Pb} < 71 \\ (0.8116+0.00264*PDD(10)_{Pb})*PDD(10)_{Pb} & lead@30cm, PDD(10)_{Pb} \geq 71 \end{cases}\end{split}\]

  • M-corrected (corrected chamber reading) - TG-51 Eqn. 8:

    \[P_{ion}*P_{TP}*P_{elec}*P_{pol}*M_{raw}\]

  • kQ for Photons (cylindrical chamber-specific quality conversion factor) - TG-51 Addendum Eqn 1 & Table I:

    \[\begin{split}\begin{cases} A + B*10^-3*PDD(10)x+C*10^-5*(PDD(10)x)^2 & 63 < PDD(10)x < 86 \\ \end{cases}\end{split}\]

    Where A, B, and C are chamber-specific fitting values as given in Table I. Pylinac automatically retrieves values based on the chamber model passed to the function.

  • kQ for Electrons (cylindrical chamber-specific quality conversion factor) - Muir & Rogers 2014

    The study of Muir & Rogers was to find kecal values that could be determined soley from R50. Through Monte Carlo experiments, the optimal Pgradient was determined as well as fitting parameters for numerous common ion chambers. That study eliminates the need for Pgradient measurements. These kecal values will very likely be incorporated into the next TG-51 addendum (as has their kQ values for photons in the first addendum). From the paper, we can start with the known relationship given in Eqn. 9:

    \[k_{Q} = k_{Q,ecal} * k'_{Q}\]

    where Eqn. 11 states:

    \[k'_{Q} = a + b * R_{50}^{-c}\]

    Where a, b, and c are chamber-specific fitting values as given in Table VII and where \(k_{Q,ecal}\) is given in Table VI.

  • \(D^Q_{w}\) photon (Dose to water at 10cm from a photon beam of quality Q - TG-51 Eqn. 3:

    \[M*k_{Q}*N^{60Co}_{D,w} (Gy)\]

  • \(D^Q_{w}\) electron (Dose to water at 10cm from an electron beam of quality Q - TG-51 Eqn. 6:

    \[M*P^Q_{gr}*k'_{R_{50}}*k_{ecal}*N^{60Co}_{D,w} (Gy)\]

Function-based Use#

Using the TG-51 module can be complementary to your existing workflow, or completely replace it. For example, you could use the kQ function to calculate kQ and then calculate the other corrections and values yourself. If you want something a little more complete, you can use the TG51Photon, TG51ElectronLegacy and TG51ElectronModern classes which will calculate all necessary corrections and values.

Note

The Photon class uses kQ values from the TG-51 addendum. The Legacy Electron class will make the user specify a kecal value and measure Pgradient. The Modern Electron class will calculate kQ completely from R50 and the chamber from Muir & Rogers 2014 paper, no kecal or Pgradient needed.

"""A script to calculate TG-51 dose using pylinac functions and following the TG-51 photon form"""
from pylinac.calibration import tg51

ENERGY = 6
TEMP = 22.1
PRESS = tg51.mmHg2kPa(755.0)
CHAMBER = "30013"  # PTW
P_ELEC = 1.000
ND_w = 5.443  # Gy/nC
MU = 200
CLINICAL_PDD = 66.5

# Section 4 (beam quality)
# since energy is 6MV, PDDx == PDD, but we'll run it through anyway just for show
pdd10x = tg51.pddx(pdd=66.4, energy=ENERGY)

# Section 5 (kQ)
kq = tg51.kq_photon_pddx(chamber=CHAMBER, pddx=pdd10x)
# Alternatively, get kQ from TPR (way quicker to measure, without needing to measure TPR!)
tpr = tg51.tpr2010_from_pdd2010(pdd2010=(38.0 / 66.4))
kq = tg51.kq_photon_tpr(chamber=CHAMBER, tpr=tpr)

# Section 6 (Temp/Press)
p_tp = tg51.p_tp(temp=TEMP, press=PRESS)

# Section 7 (polarity)
m_reference = (25.66, 25.67, 25.66)
m_opposite = (25.67, 25.67, 25.68)
p_pol = tg51.p_pol(m_reference=m_reference, m_opposite=m_opposite)

# Section 8 (ionization)
m_reduced = (25.61, 25.62)
p_ion = tg51.p_ion(
    voltage_reference=300,
    voltage_reduced=150,
    m_reference=m_reference,
    m_reduced=m_reduced,
)

# Section 9 (M corrected)
m_corr = tg51.m_corrected(
    p_ion=p_ion, p_tp=p_tp, p_elec=P_ELEC, p_pol=p_pol, m_reference=m_reference
)

# Section 10 (dose to water @ 10cm)
dose_10 = m_corr * kq * ND_w
dose_10_per_mu = dose_10 / MU

# Section 11 (dose/MU to water @ dmax)
dose_ddmax = dose_10_per_mu / CLINICAL_PDD

# Done!
print(dose_ddmax)

Class-based Use#

"""A script to calculate TG-51 dose using pylinac classes and following the TG-51 photon form"""
from pylinac.calibration import tg51

ENERGY = 6
TEMP = 22.1
PRESS = tg51.mmHg2kPa(755.0)
CHAMBER = "30013"  # PTW
P_ELEC = 1.000
ND_w = 5.443  # Gy/nC
MU = 200
CLINICAL_PDD = 66.5

tg51_6x = tg51.TG51Photon(
    unit="TrueBeam1",
    chamber=CHAMBER,
    temp=TEMP,
    press=PRESS,
    n_dw=ND_w,
    p_elec=P_ELEC,
    measured_pdd10=66.4,
    lead_foil=None,
    clinical_pdd10=66.5,
    energy=ENERGY,
    voltage_reference=-300,
    voltage_reduced=-150,
    m_reference=(25.65, 25.66, 25.65),
    m_opposite=(25.64, 25.65, 25.65),
    m_reduced=(25.64, 25.63, 25.63),
    mu=MU,
    tissue_correction=1.0,
)

# Done!
print(tg51_6x.dose_mu_dmax)

# examine other parameters
print(tg51_6x.pddx)
print(tg51_6x.kq)
print(tg51_6x.p_ion)

# change readings if you adjust output
tg51_6x.m_reference_adjusted = (25.44, 25.44, 25.43)
# print new dose value
print(tg51_6x.dose_mu_dmax_adjusted)

# generate a PDF for record-keeping
tg51_6x.publish_pdf(
    "TB1 6MV TG-51.pdf",
    notes=["My notes", "I used Pylinac to do this; so easy!"],
    open_file=False,
)

TRS-398#

Warning

Pylinac does not calculate electron dose in any other conditions than water; i.e. no solid water.

Equation Definitions#

  • Ktp (Temp/Pressure correction):

    \[\frac{273.2+T}{273.2+22} * \frac{101.33}{P}\]

    Warning

    Temperature is in Celsius and pressure is in kPa. Use the helper functions fahrenheit2celsius, mmHg2kPa, and mbar2kPa as needed.

  • Kpol (Polarity correction):

    \[\frac{|M^+_{raw}|+|M^-_{raw}|}{2*M_{raw}}\]

  • Ks (Ion collection correction; only for pulsed beams):

    \[a_{0} + a_{1}*(\frac{M_{1}}{M_{2}}) + a_{2}*(\frac{M_{1}}{M_{2}})^2\]

  • Zref (Reference electron depth; cm) - TRS-398 7.2:

    \[0.6*R_{50} - 0.1\]

  • R50 (Beam quality specifier; 50% dose depth; cm) - TRS-398 7.1:

    \[\begin{split}\begin{cases} 1.029*I_{50}-0.06 (cm) & 2\leq I_{50}\leq 10 \\ 1.059*I_{50}-0.37 (cm) & I_{50}\gt 10 \\ \end{cases}\end{split}\]

  • \(D^Q_{w}\) photon (Dose to water at Zref from a photon or electron beam of quality Q - TRS-398 7.3:

    \[D_{w,Q} = M_{Q}*N_{D,w,Qo}*k_{Q,Qo} (Gy)\]

  • M-corrected (corrected chamber reading):

    \[M_{Q} = k_{s}*k_{TP}*K_{elec}*K_{pol}*M_{1}\]

  • kQ,Qo for Photons (cylindrical chamber-specific quality conversion factor): TRS-398 Table 6.III

  • kQ for Electrons (cylindrical chamber-specific quality conversion factor; calibrated in Co-60): TRS-398 Table 7.III

Function-based Use#

"""A script to calculate TRS-398 dose using pylinac functions and following the TRS-398 photon form"""
from pylinac.calibration import trs398

TEMP = 22.1
PRESS = trs398.mmHg2kPa(755.0)
CHAMBER = "30013"  # PTW
K_ELEC = 1.000
ND_w = 5.443  # Gy/nC
MU = 200


# Section 3 (dosimeter corrections)
k_tp = trs398.k_tp(temp=TEMP, press=PRESS)
k_pol = trs398.k_pol(
    m_reference=(25.66, 25.67, 25.66), m_opposite=(25.65, 25.66, 25.66)
)
k_s = trs398.k_s(
    voltage_reference=300,
    voltage_reduced=150,
    m_reference=(25.66, 25.67, 25.66),
    m_reduced=(25.63, 25.65, 25.64),
)
m_corrected = (
    trs398.m_corrected(
        m_reference=(25.66, 25.67, 25.66),
        k_tp=k_tp,
        k_elec=K_ELEC,
        k_pol=k_pol,
        k_s=k_s,
    )
    / MU
)

# Section 4 (kQ + dose at zref)
kq = trs398.kq_photon(chamber=CHAMBER, tpr=(39.2 / 68.1))
dose_mu_zref = m_corrected * ND_w * kq

# Section 5 (Dose at zmax)
# SSD setup
CLINICAL_PDD = 66.5
dose_mu_zmax = dose_mu_zref * 100 / CLINICAL_PDD

# SAD setup
CLINICAL_TMR = 0.666
dose_mu_zmax = dose_mu_zref / CLINICAL_TMR

# Done!
print(dose_mu_zmax)

Class-based Use#

"""A script to calculate TRS-398 dose using pylinac classes and following the TRS-398 photon form"""
from pylinac.calibration import trs398

ENERGY = 6
TEMP = 22.1
PRESS = trs398.mmHg2kPa(755.0)
CHAMBER = "30013"  # PTW
K_ELEC = 1.000
ND_w = 5.443  # Gy/nC
MU = 200
CLINICAL_PDD = 66.5

trs398_6x = trs398.TRS398Photon(
    unit="TrueBeam1",
    setup="SSD",
    chamber=CHAMBER,
    temp=TEMP,
    press=PRESS,
    n_dw=ND_w,
    clinical_pdd_zref=CLINICAL_PDD,
    tpr2010=(38.2 / 66.6),
    energy=ENERGY,
    fff=False,
    k_elec=K_ELEC,
    voltage_reference=-300,
    voltage_reduced=-150,
    m_reference=(25.65, 25.66, 25.65),
    m_opposite=(25.64, 25.65, 25.65),
    m_reduced=(25.64, 25.63, 25.63),
    mu=MU,
    tissue_correction=1.0,
)

# Done!
print(trs398_6x.dose_mu_zmax)

# examine other parameters
print(trs398_6x.kq)
print(trs398_6x.k_s)
print(trs398_6x.k_tp)

# change readings if you adjust output
trs398_6x.m_reference_adjusted = (25.44, 25.44, 25.43)
# print new dose value
print(trs398_6x.dose_mu_zmax_adjusted)

# generate a PDF for record-keeping
trs398_6x.publish_pdf(
    "TB1 6MV TRS-398.pdf",
    notes=["My notes", "I used Pylinac to do this; so easy!"],
    open_file=False,
)

TG-51 API Documentation#

pylinac.calibration.tg51.mmHg2kPa(mmHg: float) → float[source]#

Utility function to convert from mmHg to kPa.

pylinac.calibration.tg51.mbar2kPa(mbar: float) → float[source]#

Utility function to convert from millibars to kPa.

pylinac.calibration.tg51.fahrenheit2celsius(f: float) → float[source]#

Utility function to convert from Fahrenheit to Celsius.

pylinac.calibration.tg51.tpr2010_from_pdd2010(*, pdd2010: float) → float[source]#

Calculate TPR20,10 from PDD20,10. From TRS-398 pg 62 and Followill et al 1998 eqn 1.

pylinac.calibration.tg51.p_tp(*, temp: float, press: float) → float[source]#

Calculate the temperature & pressure correction.

Parameters:

  • temp (float (17-27)) – The temperature in degrees Celsius.

  • press (float (91-111)) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

pylinac.calibration.tg51.p_pol(*, m_reference: float | list | tuple | ndarray, m_opposite: float | list | tuple | ndarray) → float[source]#

Calculate the polarity correction.

Parameters:

  • m_reference (number, array) – The readings of the ion chamber at the reference polarity and voltage.

  • m_opposite (number, array) – The readings of the ion chamber at the polarity opposite the reference. The sign does not make a difference.

Raises:

BoundsError if calculated Ppol is >1% from 1.0. –

pylinac.calibration.tg51.p_ion(*, voltage_reference: int, voltage_reduced: int, m_reference: float | list | tuple | ndarray, m_reduced: float | list | tuple | ndarray) → float[source]#

Calculate the ion chamber collection correction.

Parameters:

  • voltage_reference (int) – The “high” voltage; same as the TG51 measurement voltage.

  • voltage_reduced (int) – The “low” voltage; usually half of the high voltage.

  • m_reference (float, iterable) – The readings of the ion chamber at the “high” voltage.

  • m_reduced (float, iterable) – The readings of the ion chamber at the “low” voltage.

Raises:

BoundsError if calculated Pion is outside the range 1.00-1.05. –

pylinac.calibration.tg51.d_ref(*, i_50: float) → float[source]#

Calculate the dref of an electron beam based on the I50 depth.

Parameters:

i_50 (float) – The value of I50 in cm.

pylinac.calibration.tg51.r_50(*, i_50: float) → float[source]#

Calculate the R50 depth of an electron beam based on the I50 depth.

Parameters:

i_50 (float) – The value of I50 in cm.

pylinac.calibration.tg51.kp_r50(*, r_50: float) → float[source]#

Calculate k’R50 for Farmer-like chambers.

Parameters:

r_50 (float (2-9)) – The R50 value in cm.

pylinac.calibration.tg51.pq_gr(*, m_dref_plus: float | list | tuple | ndarray, m_dref: float | list | tuple | ndarray) → float[source]#

Calculate PQ_gradient for a cylindrical chamber.

Parameters:

  • m_dref_plus (float, iterable) – The readings of the ion chamber at dref + 0.5rcav.

  • m_dref (float, iterable) – The readings of the ion chamber at dref.

pylinac.calibration.tg51.m_corrected(*, p_ion: float, p_tp: float, p_elec: float, p_pol: float, m_reference: float | list | tuple | ndarray) → float[source]#

Calculate M_corrected, the ion chamber reading with all corrections applied.

Parameters:

  • p_ion (float (1.00-1.05)) – The ion collection correction.

  • p_tp (float (0.92-1.08)) – The temperature & pressure correction.

  • p_elec (float (0.98-1.02)) – The electrometer correction.

  • p_pol (float (0.98-1.02)) – The polarity correction.

  • m_reference (float, iterable) – The raw ion chamber reading(s).

Return type:

float

pylinac.calibration.tg51.pddx(*, pdd: float, energy: int, lead_foil: str | None = None) → float[source]#

Calculate PDDx based on the PDD.

Parameters:

  • pdd ({>62.7, <89.0}) – The measured PDD. If lead foil was used, this assumes the pdd as measured with the lead in place.

  • energy (int) – The nominal energy in MV.

  • lead_foil ({None, '30cm', '50cm'}) – Applicable only for energies >10MV. Whether a lead foil was used to acquire the pdd. Use None if no lead foil was used and the interim equation should be used. This is the default Use 50cm if the lead foil was set to 50cm from the phantom surface. Use 30cm if the lead foil was set to 30cm from the phantom surface.

pylinac.calibration.tg51.kq_photon_pddx(*, chamber: str, pddx: float) → float[source]#

Calculate kQ based on the chamber and clinical measurements of PDD(10)x. This will calculate kQ for photons for CYLINDRICAL chambers only.

Parameters:

  • chamber (str) – The chamber of the chamber. Valid values are those listed in Table III of Muir and Rogers and Table I of the TG-51 Addendum.

  • pddx ({>63.0, <86.0}) –

    The PHOTON-ONLY PDD measurement at 10cm depth for a 10x10cm2 field.

    Note

    Use the pddx() function to convert PDD to PDDx as needed.

    Note

    Muir and Rogers state limits of 0.627 - 0.861. The TG-51 addendum states them as 0.63 and 0.86. The TG-51 addendum limits are used here.

pylinac.calibration.tg51.kq_photon_tpr(*, chamber: str, tpr: float) → float[source]#

Calculate kQ based on the chamber and clinical measurements of TPR20,10. This will calculate kQ for photons for CYLINDRICAL chambers only.

Parameters:

  • chamber (str) – The chamber of the chamber. Valid values are those listed in Table III of Muir and Rogers and Table I of the TG-51 Addendum.

  • tpr ({>0.630, <0.860}) –

    The TPR(20,10) value.

    Note

    Use the tpr2010_from_pdd2010() function to convert from PDD without needing to take TPR measurements.

pylinac.calibration.tg51.kq_electron(*, chamber: str, r_50: float) → float[source]#

Calculate kQ based on the chamber and clinical measurements. This will calculate kQ for electrons for CYLINDRICAL chambers only according to Muir & Rogers.

Parameters:

  • chamber (str) – The chamber of the chamber. Valid values are those listed in Tables VI and VII of Muir and Rogers 2014.

  • r_50 (float) – The R50 value in cm of an electron beam.

class pylinac.calibration.tg51.TG51Photon(*, institution: str = '', physicist: str = '', unit: str, measurement_date: str = '', temp: float, press: float, chamber: str, n_dw: float, p_elec: float, electrometer: str = '', measured_pdd10: float | None = None, lead_foil: str | None = None, clinical_pdd10: float, energy: int, fff: bool = False, voltage_reference: int, voltage_reduced: int, m_reference: float | list | tuple | ndarray, m_opposite: float | list | tuple | ndarray, m_reduced: float | list | tuple | ndarray, mu: int, tissue_correction: float = 1.0, m_reference_adjusted: float | list | tuple | ndarray | None = None)[source]#

Class for calculating absolute dose to water using a cylindrical chamber in a photon beam.

Parameters:

  • institution (str) – Institution name.

  • physicist (str) – Physicist performing calibration.

  • unit (str) – Unit name; e.g. TrueBeam1.

  • measurement_date (str) – Date of measurement. E.g. 10/22/2018.

  • temp (float) – The temperature in Celsius. Use fahrenheit2celsius() to convert if necessary.

  • press (float) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

  • energy (float) – Nominal energy of the beam in MV.

  • chamber (str) – Chamber model. Must be one of the listed chambers in TG-51 Addendum.

  • n_dw (float) – NDW value in Gy/nC.

  • p_elec (float) – Electrometer correction factor; given by the calibration laboratory.

  • measured_pdd10 (float) – The measured value of PDD(10); will be converted to PDDx(10) and used for calculating kq.

  • lead_foil ({None, '50cm', '30cm'}) – Whether a lead foil was used to acquire PDD(10)x and where its position was. Used to calculate kq.

  • clinical_pdd10 (float) – The PDD used to correct the dose at 10cm back to dmax. Usually the TPS PDD(10) value.

  • voltage_reference (int) – Reference voltage; i.e. voltage when taking the calibration measurement.

  • voltage_reduced (int) – Reduced voltage; usually half of the reference voltage.

  • m_reference (float, tuple) – Ion chamber reading(s) at the reference voltage.

  • m_opposite (float, tuple) – Ion chamber reading(s) at the opposite voltage of reference.

  • m_reduced (float, tuple) – Ion chamber reading(s) at the reduced voltage.

  • mu (int) – The MU delivered to measure the reference reading. E.g. 200.

  • fff (bool) – Whether the beam is FFF or flat.

  • tissue_correction (float) – Correction value to calibration to, e.g., muscle. A value of 1.0 means no correction (i.e. water).

class pylinac.calibration.tg51.TG51ElectronLegacy(*, institution: str = '', physicist: str = '', unit: str = '', measurement_date: str = '', energy: int, temp: float, press: float, chamber: str, k_ecal: float, n_dw: float, electrometer: str = '', p_elec: float, clinical_pdd: float, voltage_reference: int, voltage_reduced: int, m_reference: float | list | tuple | ndarray, m_opposite: float | list | tuple | ndarray, m_reduced: float | list | tuple | ndarray, m_gradient: float | list | tuple | ndarray, cone: str, mu: int, i_50: float, tissue_correction: float = 1.0, m_reference_adjusted=None)[source]#

Class for calculating absolute dose to water using a cylindrical chamber in an electron beam.

Parameters:

  • institution (str) – Institution name.

  • physicist (str) – Physicist performing calibration.

  • unit (str) – Unit name; e.g. TrueBeam1.

  • measurement_date (str) – Date of measurement. E.g. 10/22/2018.

  • temp (float (17-27)) – The temperature in degrees Celsius.

  • press (float (91-111)) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

  • chamber (str) – Chamber model; only for bookkeeping.

  • n_dw (float) – NDW value in Gy/nC. Given by the calibration laboratory.

  • k_ecal (float) – Kecal value which is chamber specific. This value is the major difference between the legacy class and modern class where no kecal is needed.

  • p_elec (float) – Electrometer correction factor; given by the calibration laboratory.

  • clinical_pdd (float) – The PDD used to correct the dose back to dref.

  • voltage_reference (float) – Reference voltage; i.e. voltage when taking the calibration measurement.

  • voltage_reduced (float) – Reduced voltage; usually half of the reference voltage.

  • m_reference (float, tuple) – Ion chamber reading(s) at the reference voltage.

  • m_opposite (float, tuple) – Ion chamber reading(s) at the opposite voltage of reference.

  • m_reduced (float, tuple) – Ion chamber reading(s) at the reduced voltage.

  • mu (int) – The MU delivered to measure the reference reading. E.g. 200.

  • i_50 (float) – Depth of 50% ionization.

  • tissue_correction (float) – Correction value to calibration to, e.g., muscle. A value of 1.0 means no correction (i.e. water).

class pylinac.calibration.tg51.TG51ElectronModern(*, institution: str = '', physicist: str = '', unit: str = '', measurement_date: str = '', energy: int, temp: float, press: float, chamber: str, n_dw: float, electrometer: str = '', p_elec: float, clinical_pdd: float, voltage_reference: int, voltage_reduced: int, m_reference: float | list | tuple | ndarray, m_opposite: float | list | tuple | ndarray, m_reduced: float | list | tuple | ndarray, cone: str, mu: int, i_50: float, tissue_correction: float, m_reference_adjusted=None)[source]#

Class for calculating absolute dose to water using a cylindrical chamber in an electron beam.

Warning

This class uses the values of Muir & Rogers. These values are likely to be included in the new TG-51 addendum, but are not official. The results can be up to 1% different. Physicists should use their own judgement when deciding which class to use. To use a manual kecal value, Pgradient and the classic TG-51 equations use the TG51ElectronLegacy class.

Parameters:

  • institution (str) – Institution name.

  • physicist (str) – Physicist performing calibration.

  • unit (str) – Unit name; e.g. TrueBeam1.

  • measurement_date (str) – Date of measurement. E.g. 10/22/2018.

  • press (float) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

  • temp (float) – The temperature in Celsius.

  • voltage_reference (int) – The reference voltage; i.e. the voltage for the calibration reading (e.g. 300V).

  • voltage_reduced (int) – The reduced voltage, usually a fraction of the reference voltage (e.g. 150V).

  • m_reference (array, float) – The reading(s) of the chamber at reference voltage.

  • m_reduced (array, float) – The reading(s) of the chamber at the reduced voltage.

  • m_opposite (array, float) – The reading(s) of the chamber at the opposite voltage from reference. Sign of the reading does not matter.

  • k_elec (float) – The electrometer correction value given by the calibration laboratory. jyh,lykllp;ljljuhyk nmdrzj

  • chamber (str) – Ion chamber model.

  • n_dw (float) – NDW value in Gy/nC

  • p_elec (float) – Electrometer correction given by the calibration laboratory.

  • clinical_pdd (float) – The PDD used to correct the dose back to dref.

  • mu (int) – MU delivered.

  • i_50 (float) – Depth of 50% ionization

  • tissue_correction (float) – Correction value to calibration to, e.g., muscle. A value of 1.0 means no correction (i.e. water).

TRS-398 API Documentation#

pylinac.calibration.trs398.k_s(*, voltage_reference: int, voltage_reduced: int, m_reference: float | list | tuple | ndarray, m_reduced: float | list | tuple | ndarray) → float[source]#

Calculate the ion recombination effect using readings at two voltages. The voltages should have a ratio of 2, 2.5, 3, 3.5, 4, or 5.

Parameters:

  • voltage_reference (int) – The voltage at which calibration will be performed (e.g. 300V)

  • voltage_reduced (int) – The voltage which is lower than reference (e.g. 150V)

  • m_reference (array, float) – The reading(s) at the reference voltage.

  • m_reduced (array, float) – The reading(s) at the reduced voltage.

Returns:

k_s – The ion recombination factor.

Return type:

float

Raises:

  • ValueError – If the voltage ratio is not valid.

  • ValueError – If the calculated ks value is outside the range (1.0, 1.05).

pylinac.calibration.trs398.kq_photon(*, chamber: str, tpr: float) → float[source]#

Calculate the kQ factor for a photon beam given the chamber model and TPR20/10 using Table 6.III. Linear interpolation is used between given TPR ratios.

Parameters:

  • chamber (str) – Allowable chambers are those listed in Table 6.III that are also Farmer-type (e.g. Exradin A14 Farmer).

  • tpr (float) – The ratio of measured TPR(20cm) / TPR(10cm). Note that this can also be calculated from PDD. See tpr2010_from_pdd2010().

Returns:

kQ – The calculated kQ given table Table 6.III

Return type:

float

Raises:

  • KeyError – If the passed chamber is not within the acceptable list.

  • ValueError – If the TPR is not within the range defined by Table 6.III

pylinac.calibration.trs398.kq_electron(*, chamber: str, r_50: float) → float[source]#

Calculate the kQ factor for an electron beam given the chamber model and R50 using Table 7.III. Linear interpolation is used between given R50 values.

Parameters:

  • chamber (str) – The Farmer-type chambers listed in Table 7.III (e.g. PTW 30004/30012).

  • r_50 (float) – The depth of R50 in cm in water.

Returns:

kQ – The calculated kQ from Table 7.III

Return type:

float

Raises:

  • KeyError – If the passed chamber is not within the acceptable list.

  • ValueError – If the R50 is not within the range defined by Table 7.III

pylinac.calibration.trs398.m_corrected(*, m_reference, k_tp, k_elec, k_pol, k_s) → float[source]#

The fully corrected chamber reading.

Parameters:

  • m_reference (array, float) – The chamber reading(s) at the calibration position.

  • k_tp (float) – Temperature/Pressure correction. See p_tp().

  • k_elec (float) – Electrometer correction; given by the calibration laboratory.

  • k_pol (float) – Polarity correction. See p_pol().

  • k_s (float) – Ion recombination correction. See k_s().

Returns:

m – The fully corrected chamber reading.

Return type:

float

class pylinac.calibration.trs398.TRS398Photon(*, institution: str = '', physicist: str = '', unit: str = '', measurement_date: str = '', electrometer: str = '', setup: str, chamber: str, n_dw: float, mu: int, tpr2010: float, energy: int, fff: bool, press: float, temp: float, voltage_reference: int, voltage_reduced: int, m_reference: tuple | float, m_reduced: tuple | float, m_opposite: tuple | float, k_elec: float, clinical_pdd_zref: float | None = None, clinical_tmr_zref: float | None = None, tissue_correction: float = 1.0)[source]#

Calculation of dose to water at zmax and zref from a high energy photon beam. Setup can be SSD or SAD.

Parameters:

  • setup ({'SSD', 'SAD'}) – The physical setup of the calibration.

  • institution (str) – Institution name.

  • physicist (str) – Physicist performing calibration.

  • unit (str) – Unit name; e.g. TrueBeam1.

  • measurement_date (str) – Date of measurement. E.g. 10/22/2018.

  • chamber (str) – Farmer-type chamber model from Table 6.III.

  • n_dw (float) – NDw of the chamber given by the calibration laboratory.

  • mu (float, int) – The number of MU given per reading

  • energy (int) – Nominal energy of the linac in MV; e.g. 6. Bookkeeping only.

  • fff (bool) – Whether the beam is FFF or flat. Bookkeeping only.

  • tpr2010 (float) – The value of TPR(20)/TPR(10). Can be derived from PDD; see tpr2010_from_pdd2010().

  • press (float) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

  • temp (float) – The temperature in Celsius.

  • voltage_reference (int) – The reference voltage; i.e. the voltage for the calibration reading (e.g. 300V).

  • voltage_reduced (int) – The reduced voltage, usually a fraction of the reference voltage (e.g. 150V).

  • m_reference (array, float) – The reading(s) of the chamber at reference voltage.

  • m_reduced (array, float) – The reading(s) of the chamber at the reduced voltage.

  • m_opposite (array, float) – The reading(s) of the chamber at the opposite voltage from reference. Sign of the reading does not matter.

  • k_elec (float) – The electrometer correction value given by the calibration laboratory.

  • clinical_pdd_zref (optional, float) – The PDD at the depth of calibration. Use the actual percentage (e.g. 66.7 not 0.667). If not supplied the clinical_tmr_zref value must be supplied.

  • clinical_tmr_zref (optional, float) – The TMR at the depth of calibration. If not supplied the clinical_pdd_zref value must be supplied.

  • tissue_correction (float) – The correction of calibration to a medium other than water. Default value is 1 which is water. E.g. use 0.99 if calibrating to muscle.

class pylinac.calibration.trs398.TRS398Electron(*, institution: str = '', physicist: str = '', unit: str = '', measurement_date: str = '', electrometer: str = '', energy: str, cone: str, chamber: str, n_dw: float, mu: int, i_50: float, press: float, temp: float, voltage_reference: int, voltage_reduced: int, m_reference: tuple, m_reduced: tuple, m_opposite: tuple, k_elec: float, clinical_pdd_zref: float, tissue_correction: float = 1.0)[source]#

Calculation of dose to water at zmax and zref from a high energy electron beam.

Parameters:

  • institution (str) – Institution name.

  • physicist (str) – Physicist performing calibration.

  • unit (str) – Unit name; e.g. TrueBeam1.

  • measurement_date (str) – Date of measurement. E.g. 10/22/2018.

  • chamber (str) – Farmer-type chamber model from Table 6.III.

  • n_dw (float) – NDw of the chamber given by the calibration laboratory.

  • mu (float, int) – The number of MU given per reading.

  • i_50 (float) – The depth of ionization 50% in cm.

  • press (float) – The value of pressure in kPa. Can be converted from mmHg and mbar; see mmHg2kPa() and mbar2kPa().

  • temp (float) – The temperature in Celsius.

  • voltage_reference (int) – The reference voltage; i.e. the voltage for the calibration reading (e.g. 300V).

  • voltage_reduced (int) – The reduced voltage, usually a fraction of the reference voltage (e.g. 150V).

  • m_reference (array, float) – The reading(s) of the chamber at reference voltage.

  • m_reduced (array, float) – The reading(s) of the chamber at the reduced voltage.

  • m_opposite (array, float) – The reading(s) of the chamber at the opposite voltage from reference. Sign of the reading does not matter.

  • k_elec (float) – The electrometer correction value given by the calibration laboratory.

  • pdd_zref (optional, float) – The PDD at the depth of calibration. Use the actual percentage (e.g. 66.7 not 0.667). If not supplied the tmr_zref value should be supplied.

  • tissue_correction (float) – The correction of calibration to a medium other than water. Default value is 1 which is water. E.g. use 0.99 if calibrating to muscle.