2nd Year: Brachytherapy Flashcards

Question

In theory, where does the LDR seed holder place the source in the well chamber?

Answer 1

In an area of uniform response, which in theory would also be the **sweet spot**

Answer 2

Electrometer correction factor (from ADCL) Chamber calibration factor (from ADCL) A_ion (correction factor from collection efficiency at time of calibration) (from ADCL) P_ion (collection efficiency at time of measurement) (we assume this equals 1.000) Temperature and pressure

Answer 3

True This is why for Ir-192 we dpn't even consider the factor

Answer 4

Electrons produced by low energy photons have a range in air on the order of the collecting volume As such, there will be an apparent over response if pressure increases This is less apparent for higher energy photon or electron emitters because the electrons will have a large enough range to clear the volume regardless

Answer 5

A = I\*Cal Factor\*Unit Conversion factor\*C_TP I is the raw current reading in amperes Cal factor converts current reading to air kerma strength by applying electrometer correction factor, chamber calibration factor, and ion collection factors Unit conversion factor is used to convert from air-kerma strength to acvtivity. This is typically 1 / the exposure rate constant multiplied by exposure rate conversion to air-kerma C_TP is temperature and pressure correction

Answer 6

TG-40 (1994) TG-56 (1997) TG-64 (1999) Low Energy Brachytherapy Source Calibration Working Group (LEBSC WG) (2008)

Answer 7

\>= 10% of total seeds or 10 seeds, whichever is larger

Answer 8

\>= 10% of total, either whole cartridge assay or individual sources

Answer 9

10% or 2 strands, whichever is larger or 5% or 5 loose seeds from the same batch, whichever is larger

Answer 10

10% of total, whole cartridge assay in a sterile environment or 5% or 5 loose seeds from the same batch, whichever is larger

Answer 11

If calibrations... Differ by \< 3%, no action is required Differs by 3-5%, an investigation is warranted Differ by \> 5%, need to consult the manufacturer

Answer 12

If discrepancy is \< 5%, use the manufacturer spec If discrepancy is \> 5%, use clinic assay result

Answer 13

True The third party service will provide you with a assay report with information regarding the seed strength within the order

Answer 14

Source decay verification with an independent calculator Interlock checks Audiovisual checks Radiation area alert monitors PVT Timer error test Cateheter integrity checks Presence of emergency tools

Answer 15

Everything we do for daily + Assay via well counter PMI by service engineer Backup power and battery checks Dwell position offset check using film Interruption timer check Dwell time dosimetric effect (transit dose)

Answer 16

At the minimum once every 6 months

Answer 17

HDR has a very high specific activity, so you can get a activity in a small volume Then why don't we use Co-60? Because Ir-192 also has a lower photon energy than Co-60

Answer 18

Inventory check of all devices and probes Documentation of sterilization counts for all devices Device constancy (no bends, breaks, objects or insects stuck inside anything, liquid, etc)

Answer 19

E2E testing TPS model constancy check using gamma analysis

Answer 20

Increased dose optimization capabilities Outpatient treatment More stable positioning Can add packing or other instruments to increase distance to normal tissues (since treatment times are shorter, this can work, just like packing for T&O) Smaller applicators Better documentation for treatment (HDR units have automatic documentation) Reduction of exposure to workers

Answer 21

Increased potential for more serious errors More technical difficulty More complicated TPS Less clinical history/research Increased need for accuracy in dosimetry, geometry and anatomical information Increased danger from exposure to workers in an emergency situation

Answer 22

Systematic error - an error as a result of correctly following procedures, but with an inherent flaw in an assumption of either the dose calculation or deliver (Ex. incorrectly commisioned TPS) Random errors - errors due to human error, lapse in judgment, device malfunctions

Answer 23

Board certification Atleast 2 years of full-time practical training and/or supervised experience in medical physics at a site that offers both EBRT and brachytherapy services At a minimum, vendor-supplied training or authorized medical physicist trained for treatment unit and TPS Written attestation from an AMP attesting to individual's knowledge and skill for use of specified type of treatment unit

Answer 24

Indication of catheters used Dwell positions, insertion lengths, and spacing between dwell positions Isodose plots Secondary calculations QA check-off list Any available post-treatment reports

Answer 25

Checking area monitor and GM meter to verify source is retracted Verifying actual treatment time and positions agree with treatment plan values Storing the room and HDR keys in a secure location

Answer 26

Verifying patient name and treatment date Verifying decay of source strength Verifying correct system files were exported to treatment unit Verifying the use of any magnification factors Verifying step size Verifying prescription criteria are consistent with clinical intent Verifying that dose per fraction matches prescription Verifying dwell times and positions at treatment unit match those of the plan

Answer 27

Forceps Wire cutters Lead pig GM meter Timer

Answer 28

True The vast majority (97%) are either papillary (86%) or follicular (9%). Both are slow growing and curable

Answer 29

1% anaplastic

Answer 30

Inferior to the laryngeal prominence (adam's apple), anterior portion of the neck

Answer 31

Orally in the form of a liquid or pill

Answer 32

2 lobes (right and left), 8 segments Each segment is functionally independent with its own vascular inflow, outflow, and biliary drainage

Answer 33

False HCC is typically discovered late, so Y-90 radioembolization is palliative

Answer 34

TheraSphere or SIR-Spheres Both are microspheres injected by the physicists which work to limit radiation exposure. The difference is in their apparatus, microsphere construction and activity per sphere

Answer 35

CT and MR contrast enhanced images so interventional radiologist can plan vascular access Angiograms for vascular mapping **Hepatic perfusion study** (gamma camera) to determine fraction of uptake to liver and lung (shunt fraction). If shunt fraction \> 20%, treatment may be canceled SPECT and/or CT to image after treatment to confirm uptake CT, PET, or MRI no earlier than 3 months for follow up

Answer 36

Attached to a dotatate (molecule that binds to GEP-NET cells that have a molecule called somatostatin receptor on surface)

Answer 37

Primarily beta emitter Secondarily gamma emitter

Answer 38

Certain cancerous neuroendocrine tumors affecting the digestive tract (Gastroenteropancreatic neuroendocrine tumors (GEP-NETs)) These are typically slow growing tumors

Answer 39

Some activity is left in the vial. Some has decayed before administration

Answer 40

Take a PET scan using dotatte tagged with gallium-68 or a copper isotope to locate somatostatin receptor-positive tumors This scan will show you upfront the uptake of the lutathera A radiologist will sign off if they ar ea good candidate or not after discussion at tumor board Blood lab tests are performed very frequently, with certain parameters constantly checked to ensure that nothing is out of tolerance. If anything is approaching tolerance, increase frequency of blood work

Answer 41

Intravenous (IV) infusion

Answer 42

Pluvicto Lu-177 tagged PSMA-617 Used for adult men with prostate-specific membrance antigen (PSMA)-positive metastatic castration-resistant prostate cancer (mCRPC) whose cancer has worsened despite receiving traditional therapies

Answer 43

Intravenous infusion

Answer 44

6 separate infusions 6 weeks apart No amino acid administration since load on kidney is less

Answer 45

To protect the kidneys by reducing how much radiation they absorb

Answer 46

1. Prep room and bathroom with throw away padding surrounding floor, couch, toilet 2. Administer amino acid solution to patient 3. Begin lutathera administration with a slow titration (100 mL/hr for first 15 mL, then if patient tolerating well increase to 300 mL/hr for 150 mL) 4. during infusion continue amino acid administration 5. After infusion, administer amino acids for additional 2 hours 6. Patient urinates and voids prior to physicist 7. Physicist takes measurement to determine if patient can be released 8. Patient is released 9. Nuc med techs use GM counter to find any potential lingering waste 10. environmental services performs a clean up

Answer 47

Equations 2 from NRC 8.39 Had to derive the release criteria because the report does not have it pre-calculated The value is derived based off 4 total infusions, and a maximum possible dose to any one individual calculation to keep that value below 5 mSv The calculation first figures out the maximum allowed activity admiistered over the course of all 4 infusions, (310 mCi), which we well exceed, then calcualtes the corresponding dose rate at 1 meter for 310 mCi of Lu-177 (8.6 mR/hr), then divides by 4 for the dose rate per infusion (2.1 mR/hr)

Answer 48

**For the next 3 days** * Sleep in a separate bed and at least six feet away from anyone else **For the next 6 days** * Stay at least six feet away from children and pregnant women * Menstruating women should use tampons that can be flushed down toilet * Avoid using disposable items that cannot be flushed down toilet * Sit while urinating and flush toilet three times with lid down * Wash hands often, including after each toilet use * Shower immediately after discharge from the facility and shower daily * **Drink plenty of liquids** * Use separate towels, washcloths, and toothbrush from rest of household members * Do not share a toilet **For the next 6 months** * Do not become pregnant or breast feed **Additional** * Carry around a card to shown to officials anytime you may come in contact with a radiation scanner (such as at the airport)

Answer 49

True Bland embolization is the cutting off of blod supply to the tumor using alcohol. It does not add any additional radiation toxicity, so it can be paired with Lutathera.

Answer 50

Using a PET scan of PSMA tagged with a positron emitter

Answer 51

Bravos source: 3.5 mm active length Varisource: 5 mm active length

Answer 52

1. Source dosimetry information (TG-43 data) 2. Source geometry (length, weld tip, thickness, any other info), always put in by manufacturer at installation 3. Dwell position specification 4. S_k and activity for your source

Answer 53

S_k will change because activity will be different

Answer 54

1. Make a simple plan and compare dose at a point to what is expected from the tables 2. Go to data admin, look at the tables, and literally compare it directly to the TG report tables

Answer 55

Misplaced seed in the OR

Answer 56

Seeds are never assayed and calibration was wrong or Physician placed seeds in the wrong location

Answer 57

True It's pretty normal for seeds to move a bit, and it isn't unheard for some seeds to be urinated or pooped out. In rate situations they may even travel to the rest of the body. In general, if only a few seeds are misplaced, it does not make a huge dosimetric difference

Answer 58

Manually calculate the time needed to deliver dose by using PDD information

Answer 59

Immediately stop the beam Two methods to stop the beam... 1. Press the abort button 2. Unplug the power supply to the machine

Answer 60

Source gets stuck inside of the patient Either because it fell out from a kink in the needle, or the retraction mechanisms aren't working

Answer 61

1. Hit the interrupt button 2. Turn the key 3. Hit the emergency stop button 4. If nothing up until now has retracted the source, start a stop watch and enter the room 5. Press the afterloader stop button. If this doesn't retract source... 6. Use the manual hand crank 7. If none of the above has worked, physician intervention is needed to applications from patient 8. Physician will throw application into emergency pig 9. Wheel patient away from pig, and survey to ensure that no source is present in the patient 10. If a source is still present, you need to quickly run the patient to the OR for surgical removal 11. Once source is removed and in the pig, immediately move everyone from area and call radiation safety 12. Use rules of thumb and stopwatch timer to estimate dose to workers 13. Use TPS and delivered/stopped dwell times to estimate dose to patient

Answer 62

AAPM TG-59

Answer 63

1. Dose rate reading at surface of container 2. Dose rate reading 1 meter from container 3. Wipe test over 300 cm² of surface

Answer 64

Quarterly | (typically at time of source exchange)

Answer 65

Series of mechanical and sensing tests that ensure things like... Wire speed, wire force, indexing, sensors, PVT, etc **Fun fact:** many of these tests are performed with the machine open, inside of the room, MEANING, the source cable needs to be replaced by a dummy cable during PMI

Answer 66

1. In scenarios in which a **complete** surgical resection will be difficult Ex. Locally invasive tumor surrounding nerve or vessel that cannot be resected Ex. Tumor invading bone that cannot be cut away 2. For patients with prior EBRT in which normal tissue tolerances will be difficult to meet with more EBRT

Answer 67

Accelerated partial breast irradiation (APBI)

Answer 68

Mobetron A modality for intraoperative electron radiotherapy (IOERT) Uses electrons up to 12 MeV to resection site

Answer 69

Zeiss Intrabeam and Xoft Axxent

Answer 70

Electron beam accelerated down 10 cm tube that strikes a 3.2 mm diameter gold target This produces x-rays that emerge from a spherical plastic applicator available in sies 1.5 to 5 cm 6DoF positioning accommodated Suture closes cavity around applicator, skin retracted

Answer 71

False Xoft Axxent is an **electronic brachytherapy** IORT modality

Answer 72

Xoft Axxent

Answer 73

Electronic brachytherapy Miniature x-ray tube (2.2 mm diameter, 10 mm length) in a water-cooled catheter 2.5 hr lifetime Tube operates up to 50 kV and is heavily filtered, **this provides radial dose function similar to low energy brachytherapy sources** If used for breast, a 3-6 cm balloon applicator is used to treat 1 - 2 cm depth either single dose, or fractionated treatments

Answer 74

Interstitial brachytherapy

Answer 75

HAM applicator Surface applicator placed on placent with guide tubes that an HDR source can travel through. Used for surface dose irradiation of certain surface level cancers

Answer 76

Freiburg flap applicator

Answer 77

Colorectal Pancreas Gastric Abdomen Pelvis Breast gynecological

Answer 78

Novac-7 LIAC Mobetron (most commonly used)

Answer 79

When tumor site is in close proximity to rib or chest wall

Answer 80

1. Since the source is not shielded on the side facing away from patient surface, you need heavy shielding for vaults. Additionally, the patient rest of body will also be given considerable dose 2. Treatment times are relatively long (an excess of an hour in some cases)

Answer 81

Calibration V4.0 (more accurate) TARGIT (more commonly used)

Answer 82

Both are a function of distance from the source Both are measured by Zeiss Both are measured in a water phantom Both are measured in increments of 0.5 mm from depths 3 to 45 mm

Answer 83

14% to 30% difference at surface of a spherical applicator Difference depends on diameter

Answer 84

Send it back to the manufacturer There it gets inspection, recertification, verification/updating of the dose rate data

Answer 85

1. Because they used two different chambers to measure the dose distribution The V4.0 uses a 0.005 cc parallel-plate chamber TARGIT uses a 0.02 cc parallel plate chamber 2. The TARGIT trial measures exposure then converts using 0.881 cGy/R (this is not specific to the photon energy spectrum of the INTRABEAM however, and so is not entirely accurate). The Calibration V4.0 has absorbed dose in water calibrations for different peak voltages

Answer 86

This was a clinical trial that began in 1998 in which 2000 patients were treated As part of the trial, a formalism was created and given to all participating sites so every single site would be using the exact same dose rate at applicator surface (20 Gy at surface regardless of applicator size or any new protocol)

Answer 87

This is partially true, partially false One system allows you to (INTRABEAM 600) One system forces you to use TARGIT (INTRABEAM PRS500)

Answer 88

If you have INTRABEAM 600 you can use either option since both are available If you don't have the choice, then of course you must use TARGIT

Answer 89

Calibration V4.0 if available

Answer 90

Probe adjuster check (rotating the probe to make sure it still stays center in holder) Dynamic offsets (using photodiode to determine position of photons coming out of the accelerator) PDA source check PAICH (output check with spatially designed parallel-plate type chamber) ERM check (dose rate check)

Answer 91

It was a two check system The first shield is the internal radiation monitor which stops treatment after prescription is given The second shield is the timer, which stops treatment if the time exceeds 10% of what was expected

Answer 92

Lumpectomy

Answer 93

Hold grid in place, grab all needles, and pull Physician performs

Answer 94

Pull out catheter and dump in pig. Connect two translucent rubes to resume oxygen supply to patient Physicist performs

Answer 95

Connect syring and deflate balloon and pull from patient Physician performs

Answer 96

Remove gauze, loosen locking nuts, spread ovoids apart, remove only the offending applicator and keep removing applicators if the dose remains high Physician performs

Answer 97

Deflate balloons and withdraw them both, loosen locking nuts, spread ovoids apart, retract offending applicator, and keep removing applicators if radiation is still high Physician performs

Answer 98

Engage locking mechanism, collapse device, and withdraw from patient Physician performs

Answer 99

Connect syring to INF, collapse device and withdraw from patient Physician performs

Answer 100

Disengage chair brake, pull emergency lever to release compression paddle, wheel patient towards maze Physicist performs

Answer 101

Loosen stump nut and remove flexible probe, place probe into pig Physicist performs

Answer 102

Release centering mechanism and withdraw catheter from patient

Answer 103

1 cm: ~ ½ second 10 cm: ~ 40 seconds

Answer 104

In the beginning, only LDR data existed, but HDR was starting to become more frequently used. So PDR was used as a transitional delivery method while the change was being made from LDR to HDR

Answer 105

They're essentially the exact same thing, but PDR delivers fractions of the total dose at preset times Both use an afterloader and the same sources

Answer 106

HDR with Ir-192 or Co-60 Axxent Zeiss INTRABEAM Esteya (Elekta)

Answer 107

E&Z BEBIG (formerly Mick)

Answer 108

There is no one recommendation. But… For materials and applicators that are water equivalent, TG-43 is acceptable For molds/flabs that aren't water equivalent, a TG-43 hybrid is recommended For cone applicators or other shapes that aren't water equivalent such as Axxent or Intrabeam, use published dose distribution measurements If model based dose calculation algorithms are available at the clinic, consider using them

Answer 109

1. Does not account for heterogeneities in patient or applicator 2. Does not account for interseed attenuation 3. Does not account for patient dimensional boundaries

Answer 110

1. **1D ray tracing** - this ultimately failed to account for secondary scatter and is no longer used 2. **Collapsed Cone Convolution/Superposition (Elekta)** - Ray tracing used to scale primary fluence and primary scatter but multiple scattering is not accounted for 3. **Grid Based Boltzmann-Equation Solvers (Like Acuros)** - attempts to solve boltzmann equation by discretizing spatial, angular and energy 4. **Monte Carlo** - solves boltzmann equation through random sampling

Answer 111

The first term is dose to medium calculated in a medium The second term is dose to water calculated in a medium **TG-186 recommends dose to medium in medium** The 2nd term needs a conversion of dose to medium to water, and is often considered less accurate due to the conversion step. For **EBRT this discrepancy can be up to 2%**, but for **low energy sources, this discrepancy can be up to 80-90%**

Answer 112

False Because of the lower energies in brachytherapy, there is more significant difference between soft tissue and water than there is in EBRT

Answer 113

CT voxel by voxel material determination in order to figure out… Atomic number Cross section vs energy Effecive atomic number as a function of energy

Answer 114

Within the soft tissue range, -100 to 100 HU, for low energy sources, it is very difficult and somewhat a guessing game to determine exactly which tissue type and corresponding medium information

Answer 115

Homogenous - compare against TG-43 protocol calculation in water phantom for a single dwell position. 2% tolerance or gamma analysis of 2%/2mm with pass rate \> 99% Heterogenous - compare against MC calculated dose that has been calc'd in a heterogenous phantom. 2%/2 mm with pass rate \> 99%

Answer 116

As distance from source increases, dosimetric uncertainty **increases** As CT voxel size decreases, dosimetric uncertainty **increases**

Answer 117

True If all empiracle data is based off TG-43, then TG-43 should be used

Answer 118

Pd-103 Data is starting to show slightly increased control while reducing side effects

Answer 119

Shorter half-life A high gleason score means the cancer is more aggrssive, so you would want to give dose as quickly as possible

Answer 120

Code of practice for brachytherapy physics Goes through recommendations of what makes a good brachytherapy program. This includes documentation, workflow, recommended quality checks, etc

Answer 121

False Almost true… you don't actually know the activity of a source, you only know the apparent activity. So **apparent activity** must be specified in the TPS for each source

Answer 122

Total seed strength required to deliver given dose to a tumor of measured dimensions **Independent variable:** size of target volume **Dependent variable:** Total cumulative dose or strength utilized

Answer 123

**Manchester system** (peripheral sources define target region, and you want max uniformity) **Quimby system** (equally spaced, uniform strength sources distributed over source plane) (never picked up, **but it's uniform source placement rule is still widely used**) **Paris System** - parallel, uniformly spread source lines of equal strength and length. Yields significant normal tissue within treatment isodose line

Answer 124

T&O Eye plaques Californium-252 for advanced GYN tumors Permanent Mesh Lung Implants Intravascular brachytherapy

Answer 125

Emits gamma **and neutrons** Neutrons have high RBE and **low OER**. THis is great for hypoxic tumor cores as you'd see in advanced GYN tumors Since dose fall-off is drastic as well, the neutrons wouldn't be a big concern for the rest of the body This was the original rationale of the treatment, but is no longer used

Answer 126

P-32 or Y-90 (both beta emitters)

Answer 127

Following angioplasty or stenting of a blocked artery This is to avoid restenosis and recurrent arterial blockage due to scarring for blockages resistant to drug infuse stents or anti-coagulant drugs

Answer 128

Due to “candy wrapper effect” That is, restenosis forming at the end of the LDR stent So now HDR is exclusively done for these procedures

Answer 129

I-125 or Pd-103

Answer 130

Collaborative Ocular Melanoma Study Study which standardized treatment for brachytherapy patients (including prescription and plaques to use)

Answer 131

Ocular Melanoma

Answer 132

Proton beam therapy and enucleation (removal of eye)

Answer 133

10 mm to 22 mm diameters with 2 mm increments

Answer 134

Largest diameter of tumor + 2 mm margin Ex. if tumor max dimension is 14 mm, you want 14 + 2 + 2 = 18 mm plaque If odd number, round up

Answer 135

False Only I-125

Answer 136

Fundus Diagram

Answer 137

False For right eyes, the optic nerve enters the eye from the **left side**, and vice versa for left

Answer 138

Ultrasound or transillumination

Answer 139

Placeholder for ophthalmologist to begin suture placement around localized/marked lesion Will be replaced with the actual plaque during the surgical procedure

Answer 140

Tumor is localized using fundoscopy, ultrasound, CT or MRI From there an ophthalmologist will make the fundus diagram

Answer 141

Gold alloy i.e, it's expensive. So they are constantly sterilized and re-used And silastic insert that contains the seeds

Answer 142

1. Written directive 2. Treatment plan report and isodoses (from variseed) 3. Needle pre-plan configuration (example shown below) 4. Theragenics order form (seed needle configurations for stranded seeds, if stranded were used, otherwise pre-loading instructions) 5. Seed order confirmation 6. LDR seed calibration spreadsheet 7. Physics consult 8. Post-plan (variseed)

Answer 143

* Stranded vs unstranded * Sterile vs non-sterile * Number of seeds needed * Sleeves needed depending on applicator used * Assay services * Isotope * Activity per seed

Answer 144

I-125: after 4 weeks Pd-103: after 2-3 weeks

Answer 145

Volume study Pre-plan Seed order Receiving seeds Seed calibration Implant Post plan

Answer 146

Acquire a volume study Ask physician to contour prostate, or do it yourself with other imaging guidance if they're not available Count total number of seeds and compare with what was originally implanted Identify seeds and assign prescribed activity Calculate dose distribution and compare to original plan (this can be done with comparing dose to a point in radcalc)

Answer 147

**Monotherapy:** Patient has lower risk disease, good life expectancy, acceptable urinary function and favorable anatomy **LDR+EBRT:** Select patients with intermediate or high risk disease

Answer 148

I-125 is THE most commonly used Others include Pd-103, Cs-131, Au-198

Answer 149

To improve visibility on x-ray images Commonly are lead, silver, gold, or tungsten

Answer 150

Loose You don't know the distribution you want ahead of time so you can't pre-plan a strand

Answer 151

Seeds are less likely to migrate Less radiation exposure to staff

Answer 152

Better control of distribution optimization on the spot

Answer 153

In general, as half-life of a LDR prostate seed increases, the prescribe dose **decreases** Since you're giving dose over a shorter time, you need to give less dose in order to give the same biological effect as a longer half-life isotope with higher dose over longer time

Answer 154

Because edits may be made to strategy due to unforeseen medical circumstances arising during the implant procedure

Answer 155

Several days to weeks before the implant

Answer 156

2-3 weeks Any earlier than that and the prostate may change significantly

Answer 157

Trans-rectal ultrasound This is because it A) gives a nice visualization of the prostate, bladder and urethra, and B) is the exact setup that will be used when implanting the seeds

Answer 158

The base of the prostate refers to the most **superior** portion of the gland, and the apex refers to the most **inferior** portion

Answer 159

Once the volume of the target is measured, the nomogram is used to predict how many seeds would need to be ordered This holds true for both pre-planning and live-planning

Answer 160

The Pubic Arch You need to be able to access the entire prostate, and you can't send needles through bone

Answer 161

Anterior-lateral sectors

Answer 162

Foley catheter

Answer 163

Live-planning allows you to plan in the exact setup that the patient is in during the implants Live-planning is also more difficult and faster paced since you need to do more inside of the OR. There is more possibility of error. And it also increases staff dose since you're in proximity to sources for a longer time since pre-loading is not possible without a pre-plan

Answer 164

Before the procedure to get a baseline After the procedure to either ensure no radiation present (HDR), or to see if release is possible (LDR)

Answer 165

Seed migration (can be limited using stranded seeds) Edema (which increases volume of prostate by 40-50% soon after procedure)

Answer 166

Ensure quality of implant and dosimetric coverage Provide ongoing quality control metrics Verify seed count Give clinician opportunity to anticipate potential complications or to implant additional seeds or supplement with EBRT

Answer 167

Immediately after or within 24 hours It allows you to make any corrections on the spot as soon as possible However this will cause coverage to be underestimated by about 10% since prostate volume will seemingly increase

Answer 168

After 30 days 73% of clinics use this according to ABS survey in 2010

Answer 169

1. It was rare 2. New tech and manufacturing makes it even less likely 3. X-ray generated unecessary dose to brain or lung 4. Even if it was discovered, a procedure to remove the seed is more dangerous than keeping the seed there itself

Answer 170

False Due to the seeds having no signal in MRI, it's not practical to use. Instead CT is the most commonly used (and in some isntances CT + MRI may be used to contour the prostate)

Answer 171

D = initial dose rate \* *1.443* \* T_½ or D = initial dose rate \* mean time

Answer 172

1. Preliminary written directive (dose, isotope, signature, date of signature) 2. Final written directive (activity per source, total activity implanted, prescribed dose, consult requested or not, signature, date of signature) 3. Room survey (performed by, date, meter model and SN, reading, trash reading, linen reading, OR table reading) 4. Seed inventory data (seeds ordered, seeds implanted, leftover seeds, who performed inventory, activity per seed)

Answer 173

Patient names, prescription, #seeds ordered, #seeds used, remaining seeds, total initial measured activity of remaining seeds and all other preceeding checking dates, Date of disposal Exposure reading at disposal Method of exposure Time in storage (10 half-lives)

Answer 174

Uniformity within target volume Sharp dose gradient outside of target volume

Answer 175

Per the Paterson-Parker implant rules, the larger the cross sectional area of a target is, the **smaller** the contribution of activity from the periphery will be

Answer 176

We use plastic. But they can also be made of… Titanium Surgical steel

Answer 177

Pro: It's the most durable of the available material Con: It produces the worst CT artifacts of the available material

Answer 178

3T The implication of this being that for most clinical MRI's, titanium will be MR safe

Answer 179

When EBRT fails to shrink the tumor size efficiently enough such that intracavitary implants alone are able to get satisfactor coverage Intersitital needles, typically two or three, would be used along side the T&O or T&R implants for bulky disease to help improve coverage

Answer 180

When the HDR by itself is not enough to target the entire spread of disease Ex is in prostate + EBRT, where the EBRT is needed if there is disease spread to local lymph nodes. The HDR will not be able to reach the nodes

Answer 181

Breast Base of tongue H&N Sarcomas Lung cancers These have all been largely phased out by IMRT, but in rare situations you may see them

Answer 182

Cystroscopy (endoscopy through the urethra up to the bladder to check for any loose seeds)

Answer 183

Perineum area between anus and scrotum The exact muscle is the perineal body

Answer 184

Determining who is responsible for what What is everyone's role in the team?

Answer 185

1. "Best Medical" Prostate template 2. 15G “Best Medical” Plastic Flexible Needles 3. “Best Medical” Steel stylets (the thin steel needles that you put through the plastic needle to help push) 4. Civco stepper/stabilizer 5. BK Ultrasound and rectal probe 6. “RPD Inc” Slessinger Board 7. Transfer guide tubes 8. Survey meter

Answer 186

Slessinger board Yes, it is MRI safe

Answer 187

1. OR 2. Recovery room 3. CT Sim 4. HDR Vault 5. Urology 6. Recovery

Answer 188

Do needles reach the bladder/prostate interface? (if not, push is necessary)

Answer 189

Do needles reach the bladder/prostate interface? (if not, push is necessary) Needles that penetrate critical structures Bladder is full and catheter is clamped

Answer 190

Run the “pokey stick” through every needle to make sure that the lengths are consistent and there are no obstructions/broken tips

Answer 191

To ensure that nothing slipped in the time between CT sim and delivery of radiation Marking should be performed **immediately** after an acceptable CT is taken

Answer 192

1. Patient arrives at CT sim 2. CT is taken 3. If needles need to be pushed, they are pushed and CT is retaken 4. Once acceptable scan is taken, needles are marked 5. Alcohol pads are used to remove any blood outside of needles 6. Visual inspection is performed to ensure nothing is inside of the needles 7. Patient is transferred onto mobile bed 8. Patient transferred to HDR vault 9. Treatment planning begins 10. Once the needles have been numbered on the grid, one physicist (resident) goes in and marks with colors 11. AMP double checks color marks 12. Resident hooks up TGTs to afterloader 13. Resident hooks up TGTs to needles 14. Treatment plan is completed 15. AU planning approves 16. AMP performs checks 17. AMP treatment approves and exports to treatment delivery system 18. (in the case of Bravos, path lengths and obstructions are checked by afterloader), otherwise physicist runs wire manually through all channels (this would've been done before step 13) 19. Final treatment time-out is performed with everyone present, ensure emergency pig is by afterloader 20. Deliver treatment 21. Physicist unhooks TGTs from needles 22. Nurse removes sutures 23. Physician removes needles and template

Answer 193

Correct patient Correct fraction number Correct dose/Fx Correct activity of the day Total curie-seconds agrees with any previous treatments (or with nomogram) Total treatment time on console = treatment plan No obstructions in needles and lengths make sure Correct channel needles are identified on plan vs in real life No dwell times \< 0.4 seconds Secondary dose check is within tolerance

Answer 194

Check the longitudinal difference between that needle and a correctly marked needle Go to CT, double check the longitudinal difference between the same two needle ends on that as well If they agree with one another, then a push was not necessary and the marks were just poorly made Alternatively, you can check the longitudinal location of the two needle tips, and the difference should also be the distance between the connection ends (since all needles are the same length)

Answer 195

Channel 1 is tandem Channel 2 is pt right ovoid Channel 3 is pt left ovoid

Answer 196

Build-up of clear fluid inside of the body Most commonly occurs after surgery

Answer 197

Chest wall, rib, skin, lung

Answer 198

1 cm annulus around balloon, subtracting out balloon and air/seroma And subtracting any PTV that extends closer than 5 mm to skin surface And subtracting any PTV that extends into ribs or pectoralis muscles For PTV\_Eval, subtract the balloon from the PTV

Answer 199

1. Interstitial 2. Partial breast using applicators implanted in surgical cavity 3. IORT

Answer 200

MammoSite (intracavitary balloon) Savi (strut adjusted implant)

Answer 201

Skin dose, specifically 5 mm thickness to skin surface

Answer 202

Device that fills a sphere with a saline solution. A silicone catheter is located in the cetner of the balloon (can be one applicator, or often more) Balloons are available in a number of sizes and will mold to the lumpectomy cavity tissue into a spherical shape

Answer 203

A few days This will allow time for air pockets to resolve and seroma to drain **Remember:** you need air/seroma surrounding applicator to be \< 10% of the **PTV\_Eval** **By surrounding applicator**: this means within 1 cm of applicator

Answer 204

Contura (shown below) It was a 5 channel applicator that allowed for some some additional dose optimization, oriented in a cross or X depending on orientation Additionally, we also had MammositeML which was smaller and 4 channel oriented in a Y

Answer 205

Proximity of lumpectomy cavity to skin Need at least 7 mm spacing to avoid late-term toxicity with unsatisfactory cosmesis outcome Multi-channel applicators allow for better dose shaping, thus allowing work-around from this limit

Answer 206

SAVI stands for Strut Adjusted Volume Implant It's a multi channel catheter that is shape conforming to fill the cavity

Answer 207

Intersitial needle template grid for breast HDR

Answer 208

Non-resected or irregularly shaped volumes

Answer 209

Needle tips oriented towards midline (Recall, radiation is strongest radially)

Answer 210

AccuBoost Think mammogram, but with a brachytherapy applicator attached to a holding with openings in them. Afterloader delivers the radiation. Breast compression to stabilize and remove overlapping tissue surrounding tumor Image guidance with mammogram

Answer 211

SAVI has better modulation Contura is easier to implant

Answer 212

To reduce motion artifacts and make catheter tracing easier

Answer 213

1. Marking on skin where applicator meets skin. Mark both applicator and skin This is to check for rotation of applicator (remember it's spherically symmetric, but the dose distribution isn't, so you need to be extra careful to make sure that it didn't rotate) 2. Marking to denote skin insertion depth to make sure it isn't slipping out fraction to fraction

Answer 214

Collet style

Answer 215

Run different style radio-opaque wires through one of the channels, this should give you a reference point of your “channel 1” From there you can number them CW

Answer 216

For cases in which site is near critical structure, and a small change in anatomy can bring dose into critical structure, you should Re-CT for all AM fractions and **double check distance and air/seroma** (suck any out if needed) If re-plan is necesary, it should be done PM-fractions are typically scout only

Answer 217

Before every fraction For Mammosite, this is to check the volume of the balloon to make sure nothing changed and rotation For SAVI, this is to check expansion/size against the reference scout and rotation

Answer 218

Vaclok Arms down for comfort

Answer 219

There is a port that directly accesses the balloon for that exact purpose

Answer 220

In PDR you are moving to source more times than in HDR and in an uncontrolled/unspecialized holding area Not only is there a higher probability of machine error, but the staff in vacinity is also not specialized in radiation therapy

Answer 221

To check for rotation, make mark on applicator and on skin. Marks should align Distance of skin to hub

Answer 222

Collet Style

Answer 223

Air Seroma is not as much of an issue for SAVI procedures

Answer 224

Maximum volume of air \< 10% PTV eval

Answer 225

7, 9 or 11 Channel 1 in the center, surrounded by the other channels in a circular formal

Answer 226

Based off of the measurement of te cavity along the long axis and the daiameter of the cavity under ultrasound

Answer 227

True Essentially the procedure is that, in an emergency situation, the patient is asked to stay seated and do not stand up or aid

Answer 228

Patient set up with compression paddle Mammogram to align (IGRT) (using surgical clips in lumpectomy site) From the mamogram, the rad onc decides the position and type and shape of applicator **Consult nomogram to calculate dwell time for each opposed pair for the specific applicator. NOTE: NOMOGRAM CALC IS APPLICATOR SPECIFIC** Applicator (using grid that follows mammogram) is then snapped into place (see image below) Attach catheter of source holder to TGT, then afterloader, HDR Deliver at dwell locations specified by nomogram Remove then snap applicator to opposing location Copy and paste the plan and deliver on the opposite side Repeat the entire process again but for the two orthogonal opposed fields (if APBI) or the one orthogonal field (if boost) **Note:** For each pair of opposing fields, a mammogram, the location/size/applicator is decided, and dwell time calculations are done with the nomogram for each step of the process. So that is 2 mammograms **Note:** For Accuboost, there is no CT sim. All treatment planning is done using mammogram. And all planning is done on the spot. Total treatment is about 20 mins per fraction

Answer 229

AccuBoost is able to get a much tighter dose distribution and it uses on the spot mammogram image guidance daily

Answer 230

GammaMedPlus iX Varisource iX (used to have) Bravos (currently have)

Answer 231

Applicator type and size Planned activity from first fraction (the times will get scaled for subsequent fractions on the machine console itself) Plate separation Separation (thickness of breast) Percent isodose line Prescription (**Note:** if you have 2 sets of opposed fields, divide prescription by two and make two different nomograms for the two different pairs)

Answer 232

If it's only 1 pair of opposed fields, then 1 nomogram If it's 2 pairs of opposed fields, then 2 nomograms Essentially, 1 nomogram per opposed pair per fraction

Answer 233

Surrounding healthy lung

Answer 234

A camera (endoscope) is sent through the patient to guide catheter placement A marker wire specific to that channel will be sent through as well. Once the marker wire is fully through the catheter, the remaining length of the marker wire outside of the TGT is noted (call it ‘E’) The pulmonologist retracts the camera and on the way out decides the most distal location of the disease The marker wire is retracted out to match that location. The remaining length of the wire outside of the TGT is noted again, (Call it ‘D’) The pulmonologist retracts the camera and on the way out decides the most proximal location of the disease The marker wire is retracted to match that location. The remaining length of the wire outside of the TGT is noted again, (Call it ‘P’) The distal point is located on the CT following the catheter starting at the end then moving backwards a distance of D - E. Viewing planes are aligned to this point and a point is set. Similarly, the proximal point is located on the CT following the catheter starting at the end then moving backwards a distance of P - E. Viewing planes are aligned to this point and a point is set. **Note:** P - E will also be the last dwell location that you enter in the TPS Then in contouring, use either a 1 cm or 2 cm diameter 3D brush and draw along the catheter from distal to proximal point (edge of contour should be touching the proximal and distal points). This is your CTV. 1 cm would mean 0.5 cm margin, this is for smaller lesions. 2 cm diameter would mean 1 cm margin, this is for larger lesions. At our site we **exclusively** did 1 cm for everything

Answer 235

Push a marker wire through the catheter. The marker wires have unique patterns that will appear on the CT. Associate each pattern with the respective catheter/channel number. Mark the TGT in real life accordingly to help distinguish as well (colored markers)

Answer 236

The CRNA nurse controls the breathing period In theory also, if the breathing cycle can be monitored, which it is, a 4D CT or gated CT can be taken

Answer 237

These patients, atleast in our clinic, are almost always following a hysterectomy before their cylinder treatment

Answer 238

Largest possible cylinder that the patient can comfortably tolerate This reduces ISL fall off to get to the 0.5 cm target. Thus, the surface of the vaginal wall gets less dose the larger the cylinder is It also helps to remove air gaps at the cylinder surface And in some cases for patients with large anatomy, it lets us go deeper

Answer 239

Endometrial (lining of uterus) Treated to the vaginal cuff following a curative hysterectomy

Answer 240

Cerival cancer

Answer 241

Endobronchial Esophageal Nasopharynx

Answer 242

To anchor it in place in case the patient coughs during treatment. You don't want the catheter moving

Answer 243

1 channel It's usually just a straight shot treatment

Answer 244

An inherent flaw in all 3 of them is that, because of their cylindrical dose distribution, they can only treat small lesions Disease typically, in most cases, will not symmetrically surround a catheter/entranceway. Thus, if you want to treat large lesions, you need to pump a lot of dose to get coverage, and that results in a lot of healthy tissue getting excessive dose

Answer 245

The Manchester System

Answer 246

Surface of cylinder (that is, 100% of PTV gets prescription dose) Where the PTV is drawn as an inner wall of the cylinder. So the surface gets prescription dose

Answer 247

Endometrial

Answer 248

Cervical cancers with intrauterine disease for patients who are unsuitable for hysterectomy

Answer 249

Tandem is inserted as far into the uterus without perfurating the uterine wall The phlange (thick part of tandem) sits at the cervical os, and is often considered the surrogate for the location of the cervical os

Answer 250

Nested in the vaginal fornices

Answer 251

Steel 30, 40, 45, etc

Answer 252

To be as large as possible while also being comfortable Same rationale as with cylinders, you want to minimize dose at surface by minimizing effects of ISL while still maintaining required coverage

Answer 253

Packing and dose constraints Packing - the lock everthing in place in the fornices Dose constraints - they create separation by moving the ovoids a bit further from the bladder and rectum

Answer 254

Align viewing planes such that cervical os is horizontal in both sagittal and coronal planes (which are technically not sagittal and coronal anymore when you re-align) Go up 2 cm from cervical os **following the tandem** and 2 cm out Pt A line should be orthogonal with tandem

Answer 255

Align viewing planes such that cervical os is horizontal in both sagittal and coronal planes (which are technically not sagittal and coronal anymore when you re-align) Connect a line between the centers of the two ovoids Move superiorly for a distance equal to radius of ovoids + an additional 2 cm **following the tandem**, then 2 cm out Pt A line should be orthogonal with tandem

Answer 256

The point where the uterine arteries cross the ureters, forming the paracervical triangle It is thought that the tolerance dose here is the limiting factor, so you give prescription dose to Pt A's

Answer 257

Location of obturator nodes (one of the external iliac lymph nodes) and also the pelvic side wall In general, Pt B dose is also a good measure of the lateral spread of dose

Answer 258

ICRU 89: Connect a line between centers of the two ovoids. Move superiorly a distance equal to the radius of the ovoids + an additional 2 cm **following the midline** Old Manchester: Same thing, but start at cervical Os and only move 2 cm Your Pt B line should be orthogonal to **midline**

Answer 259

the point of maximum dose to the rectum

Answer 260

Point marked on frontal radiograph with a line drawn from midpoint of ovoid sources to 5 mm posterior of the vaginal wall

Answer 261

Point of maximum dose to the bladder

Answer 262

Locate the center of the foley catheter ballon, then draw a line to the posterior surface of the ballon. You should arrive at a point in the center-posterior portion of the balloon

Answer 263

Ribble GYN (paper by the ABS)

Answer 264

That CTV is not a real CTV. It's just a shape that we create that describes the ideal pear shape of our dose distribution. We really prescribe to get prescription dose to Pt A's A real CTV would be drawn from potentially an MRI by the physician. They do not draw that pear shaped CTV that we use in TP

Answer 265

Bravos gives initial dwell time recommendations to get the initial shape pre-normalization Give first ⅓ of tandem dwells a 15 second dwell time each, and the remaining 10 seconds Give all ovoid dwell positions a 15 second dwell time Then normalize to give prescription dose to the Pt A line The pear shape will be the 100% isodose line, and assuming a Pt A plan, we're actually done right there

Answer 266

None is offocially recommended Per Khan, there is no universal agreement as to the superiority of any one system. It's a matter of taste, ease, preference and imaging capabilities BUT, if you can figure out how to delineate the target volume, then ICRU system would be the best

Answer 267

The volume encompassed by the 60 Gy EQD2 isodose line of T&O + EBRT 60 Gy doesn't have to be used, but that's what it usually is

Answer 268

A combination of… dose to risk level target structures visualized on MRI (GTV, HR CTV, IR CTV, LR CTV) Total reference air kerma Pt A doses Bladder and rectum reference point doses And OAR volumetric constraints from Ribble

Answer 269

T2 It best visualizes tumor, cervix, bladder, vagina, rectum and sigmoid T1 may also be used to visualize extent of nodal involvement

Answer 270

Rotte “Y” Shaped Applicator Kind of looks like the fletcher, but isn't

Answer 271

True As long as everything is converted to EQD2

Answer 272

Combine it with interstitial needles It has been shown that intracavitary + interstitial yields better dose conformity, better reduction of critical structure doses, and better CTV coverage

Answer 273

Take a look at the shape of the cervice and uterus Cervix and uterus should have the shape shown below If there's gross disease, it will look “barrel-shaped”

Answer 274

If the ovoids are not snug into the fornices, Pt A will be lower than what it should be

Answer 275

Make an opti structure of the CTV standard pear cropped 0mm from all critical structures, then optimize to give that structure 100% prescription dose It will serve as an anchor to help retain the pear shape, while also removing competeing objectives that will confuse optimizer while you're trying to lower normal tissue constraints

Answer 276

Critical structure 2 cc (we include this) Pt A dose (we include this) Bladder and Rectum point doses from ICRU (we don't include this) Target D90 coverage (this is shown in DVH so we include it, **specifically for the CTV - Std Pear, not the opti!!!!)**

Answer 277

When r \> 3L Where L is the active length

Answer 278

Midline is in reference to the orientation of the bony pelvis

Answer 279

Don't be shocked that the uterus and cervix are in the same axial plane, they most definitely can be Remember, the anatomy is on a slant, it's not completely inferior to superior

Answer 280

Interseed Attenuation is not accounted for Intraseed Attention is included in the seed model, and therefore is herently accounted for in TG-43

Answer 281

1. Grayscale display accuracy 2. Depth of penetration 3. Axial and Sagittal resolution 4. Axial and Sagittal distance scales 5. Cross sectional area accuracy 6. Volumetric accuracy 7. Needle and grid alignment 8. Treatment planning computer volume accuracy

Answer 282

CIRS Model 45 phantom

Answer 283

The lower the frequency, the deeper the focal spot will be

Answer 284

High frequency

Answer 285

Higher frequency is worse depth of penetration Lower frequency is increased depth of penetration

Answer 286

LiF TLD detectors

Answer 287

False When very high exposures are present, GM meters can register zero exposure. So it's recommended that a back-up area monitor in conjunction to the GM meter should be present

Answer 288

Interstitial Intracavitary Intraluminal (subset of intracavitary) (blood vessels, bronchus, esophagus or bile duct) Surface

Answer 289

A calibrated ion chamber Typically with a large, pressurized gas-filled chamber

Answer 290

Isotope Type of source Source strength Location

Answer 291

Low average photon energies and short half-lives

Answer 292

Dorsal Lithotomy

Answer 293

Retinoblastomas 40 - 45 Gy in 2 days

Answer 294

COMS: Assume point source model for seed, no anisotropy, no heterogeneity Current AAPM recommendations: Use line source approximation, still assume homogeneity

Answer 295

Patients stay in hospital during the days of therapy Housing room must include a radiation sign posted outside of the room Patient wears special leaded glasses that reduce exposure by a factor of 5 or 6 when visitors or nursing are present Nurses require annual radiation safety training

Answer 296

Both systems were designed for radium implants, so only isotopes similar to radium (such as Ir-192 or Cs-137), may be used with the system. **Low-energy sources cannot be used with the syetms**

Answer 297

Pros: Cs-137 has a higher average energy that could be beneficial for coverage, and it has a longer half-life (meaning less replacement) Cons: Higher energy means more shielding, And Cs-137 has a lower specific activity, meaning larger source and larger catheters

Answer 298

Vaginal Cylinders are **prophylactic**. They are meant to reduce recurrences by irradiating the vaginal cuff If there's one thing you should remember, it's that endometrial and vaginal cuff are synonymous and often times used interchangeably when talking about cylinders

Answer 299

The dome of the vagina (typically upper one-third to one-half

Answer 300

True! We usually never even mention it because cylinder doses are so low to the critical structures, but yes, they are the same constraints

Answer 301

With recurring endometrial and cervical cancers post hysterectomy that relapse after surgery in and around the vaginal cuff area **with a depth greater than 5 mm** To deep for cylinder, no place for tandem

Answer 302

With recurring endometrial and cervical cancers post hysterectomy that relapse after surgery in and around the vaginal cuff area **with a depth greater than 5 mm** To deep for cylinder, no place for tandem

Answer 303

Capri applicator It's a multi-lumen (13), inflatable balloon applicator that can be used in place of a vaginal cylinder for treating vaginal cuff/endometrial cancers. Gives more dose shaping capabilities. Inserted in patient then inflated to fill space

Answer 304

Contura - balloon with multiple **curved channels** on the inside, 1 straight channel in center. Curved like savi, but they're rigid, they don't change curvature. Mammosite - balloon with 1 or more channels, **all channels are straight.** For multiple channels, you have one channel in center, others surround Savi - no balloon, curved channels fit the cavity and touch the tissue

Answer 305

It depends… What you care about the most is the separation of the channels. For contura, the separation of your channels is very slightly greater than mammosite near the center of the applicator. BUT, at the ends of the applicator, the channels meet back for contura, meaning the modulation is worse at the ends than mammosite

Answer 306

False. It should actually be… Savi has different dose constraints than mammosite and contura. **Specifically for target dose constraints.** That's because with Savi the source is touching the tissue, so some hot spots are impractically difficult to avoid

Answer 307

Study that physicians read showed that local control for IORT was poor compared to EBRT boost

Answer 308

Since channels can be deformed and bend so drastically, it became an integrity scare

Answer 309

Inconvenient, long, needed physician present the entire time, uncertainty in breast moving, and we need surgical clips ahead of time

Answer 310

We preferred EBRT which is easier

Answer 311

We used stranded seeds with spacers are the end. This allowed us to insert all seeds starting at the same depth. This is called **baseline loading**

Answer 312

TRUS Most places use it

Answer 313

CT Because you need to do some slight over-estimating

Answer 314

In the first few cm from source, ISL dominates, and that is medium independent Although it is true that water will have more attenuation, the loss in dose due to attenuation is roughly compensated by the increase in dose due to scattering. So dose in water will still be close to dose in air for the first few cm

Answer 315

TRUS, on stepper, with imaginary grid, no anesthesia Begin at the deepest depth to find the base of the prostate Step out at 5 mm increments to obtain slice by slice in the axial

Answer 316

Only the prostate (CTV) + a 3 mm margin (PTV) We did not analyze urethra and rectum wall volumetrically, we only accounted for them in seed placements visually

Answer 317

Theragenics I-125, AgX100 model We tell theragenics the activity and the date of activity that we want a batch from

Answer 318

1 cm seed separation in all directions Do not place any seeds on ‘D’ column because urethra will be there Avoid placing seeds on row ‘1’, rectum will be near there A needle needs to have at least 2 seeds Needles must be within the prostate (only exception is end slices if the volume on the slice is too small to keep them within) **Note:** If after following these rules, coverage is not met, you can increase the source activity that you want to order **Note:** even if your DVH numbers are met, you need to make sure that the isodose lines look good, (no missing coverage, no bowing in, no high dose to rectum or urethra, etc.)

Answer 319

The seeds are titanium, but TG43 (which we use in our calcs), does not take into account attenuation due to the material of a nearby seed At distances of 1 cm or more, the uncertainty in dose calc becomes small enough that we're comfortable

Answer 320

Prostate D90% \> 100% (\>95% variation) Prostate V150% \< 50% **Note:** We did not have a urethra or rectum constraint because we never contoured them

Answer 321

Consult with the physician. For I-125, 1 day is a little more than 1% loss in activity Not the end of the world, they'll likely be fine with it

Answer 322

In the case of the prostate growing between the pre-plan and the day of, we want extra strands to be able to get coverage. Or in the case of a strand being pulled out by urologist during cystoscopy Also for assay we get a single extra seed. This is because the theragenics strands are sterilized and pre-loaded. Theragenics will assay the rest

Answer 323

At the center of the active length

Answer 324

Air Kerma Strength Calibration Coefficient Gy m² / Ampere hr Order of magnitude: 10⁵

Answer 325

uGy m² / hr mCi Converts air kerma strength to activity CF = (*Γ \* w/e*)^-1

Answer 326

Standard Imaging HDR1000 Plus

Answer 327

Alpha-Omega calibrates the source in Louisiana (CST) So 12 PM CST = 1 PM EST So we tell our console that it was calibrated at 13:00 local time

Answer 328

Before attaching TGT to needles, use a small wire to check consistency of length among all needles, and also to check for obstructions Then attach TGTs to needles Then run a wire through to the end of a needle, use a screw to signal end of TGT, then remove and run through racetrack, stopping at the screw, to measure the length Doing this for every single channel for a prostate can be very time consuming, so most people only check for a random sample of 5 or 6 This is fine since you checked needle constancy earlier, and also all TGTs have the length noted at time of commissioning

Answer 329

Radium-223 (HL 11.4 days) Used to treat prostate cancer that has spread to the bone that no longer responds to hormonal or surgical treatment (treats the bone metastasis)

Answer 330

Pluvicto and Lutathera - MIM Y90 - Velocity

Answer 331

We didn't. We used decay calculation to find activity All we did was survey

Answer 332

10 half lives But we would also check at 7 half lives, and if survey is slightly above background, we could release in theory

Answer 333

Physical half-life So it's actually more conservative, since effective half-life, which is more accurate, would mean you are getting rid of the isotope quicker, so patient release can actually be lower than what we have it

Answer 334

2 mR/hr So we're actually more liberal in that sense

Answer 335

False Release if based off physical half-life, so in theory Lutathera and Pluvicto will have roughly the same release

Answer 336

[designated channel length in plan] +- 2 cm Let's say for example. Ch length = 150 cm If length measured is \> 152, bravos assumes there is no channel end and retracts the source, not allowing you to treat If length measured is \< 148, bravos will detect it as a blockage and retract

Answer 337

That's the distance prior to programmed channel length that the bravos afterloader starts to slow down the dummy wire

Answer 338

This is TRUE In fact many sites have the patient awake as it is generally easier. BUT, it introduces more uncertainty

Answer 339

False It's only good for treating bulky disease that symmetrically surrounds the catheter

Answer 340

The master monitor has a radiation detection volume in it The slave monitor has no radiation detection volume, all it does is receive the signal from the master monitor so it can start blinking inside the console area

Answer 341

Something very slightly under 200 mCi

Answer 342

The SAVI applicator has a metal mark at the middle part of a known channel. From there you number them clockwise And channel one for SAVI is always the central channel

Answer 343

* Manufacturer does a wipe test of package at time of manufacturing and packaging * Engineer does ANOTHER wipe test at time of source exchange * It's a sealed source, it's very unlikely that anything would change throughout shipping. So it's very unlikely that your wipe test would show anything that the prior wipe tests wouldn't show * And also, we measure activity on surface with a survey meter, it would touch any existing contamination, and it would show as the signal not going away as you move away from the container

Answer 344

Possible shavings, or bits of the source that are present in the air to get on the container or the wire

Answer 345

Neutron bombardment of Ir-191 (which is a naturally occuring stable isotope)

Answer 346

Ir-192 → Excited Pt-192 (95%) (beta minus then gamma emission) Ir-192 → Excited Os-192 (5%) (electron capture then gamma emission)

Answer 347

False The bladder is filled before the patient ever reached rad onc. From there the drainage is clamped so it doesn't drain

Answer 348

Brachyvision: End of weld tip Variseed: center of seed/active length

Answer 349

You want smaller weld tip, that way the active length is closer to the end of the cylinder and you can get coverage easier

Answer 350

GammaMed plus 3. 5 mm active length 0. 7 mm

Answer 351

Because bravos corrects transit times. So what ends up happening is some seconds are subtracted off from a given dwell position Below 0.4 seconds, subtracting off for transit dose gives a negative dwell time, which is an error in the system

Answer 352

Assume 10 Ci is the day of strength, then scale on the machine Many places do this For us, however, we do not do this for two reasons. 1. It's an extra step, which means extra possible chance of error 2. If a dwell time ends up being \>0.4 s for a 10 Ci plan, but your source is actually over 10 Ci, then you get the transit time issue

Answer 353

1. Make sure there are no obstructions before sending out the source wire 2. Measure channel length, and adjust plan relative to the difference. Ex. if the plan says that the end of a tandem is 150 cm, but Bravos, based off their measurement, says its 150.2 cm, then all positional data for the source cable will be adjusted by that .2 cm difference to agree with real conditions

Answer 354

To make sure there are no obstructions before sending out the source wire

Answer 355

Most likely based off pressure or tension of wire and a calibration curve

Answer 356

They wheel out the wire to the very end, retract back a certain distance to remove slack, and that distance is calibrated to a certain value. Then they wheel from there and know the relative wheeling length

Answer 357

To make sure that what the machine thinks is a position, is true

Answer 358

1. Because we can, it's very easy to measure and calibrate with bravos 2. Because bravos adjusts source positioning based off dummy wire before treatment, so you would hope that the two wires agree very closely to one another

Answer 359

False We assume that the ruler is accurate and that engineering/installation has already checked this. This is purely an assumption

Answer 360

So you can also define the deepest location of the wire to equal the channel length

Answer 361

Varisource measures distance based off sending the wire to the very end, then wheelign it back. The wheeling back requires a little bit of distance to remove slack Bravos goes off pressure or tension and in theory doesn't actually need the 0.1 cm, that 0.1 cm is just recommended for safety so the source doesn't ram into the tip

Answer 362

Tables are continuous, so there can be interpolation discrepancies Dose grid size can make a huge difference as well Location of origin of seeds make s a difference as well

Answer 363

Point dose: within 1% Gamma: nearly 100%

Answer 364

1. Read up on background information 2. Determine budgeting and required devices/equipment 3. Consider logistics (sim, scheduling, OR involvement, implants, etc.) 4. Develop a multidisciplinary standard operating procedure (SOP) for the parties involved 5. Develop an SWI as needed for role specific 6. Acceptance test the device 7. Perform an end to end 8. Get some practice planning some test patients

Answer 365

It is the idea that if you measure the exact same thing, 2 different ways, you can get different measurements Ex. If you measure dwell position by sending cable all the way to the tip and retracting back, versus measuring location based off wheeling rotations, you will likely get two different results

Answer 366

Gauze packing This is not preferred as gauze can dry up and is not as comfortable