DANIEL PRIETO MORÁN - SEFM · T1/2 = 64h (2.67 d) Tissue range: 11 – 2.5 mm. Análisis...

Análisis radioprotector de los

procedimientos diagnósticos y terapéuticos

con radioisótopos.

Directiva Euratom 59/2013.

Second Part:

Aplicación a tratamientos de Aplicación a tratamientos de

tumores hepáticos con

microesferas de Y-90

Radiofísica de la dosimetría interna en los

procedimientos terapéuticos con radiofármacos

DANIEL PRIETO MORÁN

Análisis radioprotector de los procedimientos diagnósticos y terapéuticos con radioisótopos. Directiva Euratom 59/2013

Index

Medical Physicist: Article 58

Procedure established

Results

� Dose indicators

2

� Dose indicators

� Measurements of dose rate patients. Rules

� Waste management

� Contamination measures

� Typical values in treatments

Emergency

Conclusions


Medical Physicist colaboration

Art. 58 (Procedures)

d) i) in radiotherapeutic practices other than standardised therapeutic

nuclear medicine practices, a medical physics expert shall be closely

involved;

3

involved;

� Non-standard procedure

� Unusual area (interventional radiology surgery)

� High risk of contamination

� Unencapsulated sources: Tc-99m, Y-90


TheraSphereTM

Glass microspheres

Diameter 20-30 µm

4

Diameter 20-30 µm

Activities available: 3, 5, 7, 10, 15 y 20 GBq (81-540mCi)

Y-90


Yttrium 90

Pure beta emitter

Average Energy 0.93 MeV

5

Average Energy 0.93 MeV

T1/2 = 64h (2.67 d)

Tissue range: 11 – 2.5 mm


Our Protocol:

Operation room preparation:

Background radiation measure (cps)

6

All staff with gloves, and waterproof overshoes

Placing underpads

� Close to the injection area

� Exit of de room

Two containers of radioactive waste

� Inside the operation room

� Outside (door)


7


Yttrium reception in Nuclear Medicine:

Reception and measure the dose rate

Activity verification with Dose Calibrator

(Tolerance 10%)

8

Assembly and preparation dose

Move the kit when the patient is prepared


Y-90 Kit´s trip to Radiology department

NUCLEAR MEDICINE

9


RADIOLOGY DEPARTMENT

10


Injection procedure (Contamination risk):

Injection by nuclear medicine specialist

If there were contamination

� On the patient: Clean with gauze and changing the gloves

� On the floor: Put more underpads

11

� On the floor: Put more underpads

Exit of the room

� One by one and closing the door to prevent patient

contribution

� Surface contamination detector

Return to the room with waterproof overshoes


Measures:

� Hands

12

� Feet

� Chest


Catheter removal:

Deposit it in the waste bin of methacrylate

Injection kit moved to the next room

Measure of the staff´s contamination

13

Measure of the staff´s contamination

Move the patient in the bed to the next room

Move the containers to the other room

Measure the distance traveled by the bed in the surgery room

� If there were contamination change the patient's bed

Remove the underpads and put into the container


Movement of the patient:

Measures possible contamination

� If there were contamination decontaminate

� The room will be closed if it continues

Measures of the containers

14

Measures of the containers

� Background evacuation as biowaste

� Different of background send it to warehouse of NM

Patient´s measures

� Contact (close to the liver)

� 1 m

Transfer the patient to NM Images


Index



Results

� Dose indicators

15

� Dose indicators





Emergency

Conclusions


Results

Dose Indicator

16

Tc-99m Y-90

Average Median Average Median

Time of

fluoroscope

(min)

11.18 10.87 5.16 2.54

DAP

(Gy cm2)177 151 92 69

Kerma

(mGy)1124 716 221 221


Results

Patient´s measures

17

Average Median

Dose Rate in contact(µSv/h)

26.7 27.7

Dose Rate1 m

(µSv/h)3.4 2.5


Restricting Instructions:

� T1/2= 2.67 days

� Dose Rate Average “contact”= 26.7 µSv/h

18

No pregnant proximity during 3 days

No staff pregnant during 3 days

Private room or with a patient 60 year old or more


Results

Radiactive waste

Tc-99m Y-90


Internal

Container 2.9 Background Background Background

19

Container

(µSv/h)

2.9 Background Background Background

Exterior

Container

(µSv/h)

Background Background Background Background

Methacrylate

Bin

Catheter Y90

30 cm

(µSv/h)

- - 1 0.9


Results

Backgrounds of the radiology operating rooms

Tc-99m Y-90


20

Before

intervention

(cps)

19.3 19.1 19.6 18.3

After

intervention

(cps)

21.4 21.1 21.8 20.5

Only once the room was closed (Tc-99m)


Results

Contaminations

3 cases of 24 intervention:

� All of them with Tc-99m

21

� First: Radiologist´s hands (without gloves)

� Second: On the floor at the end.

• Decontaminant gel two times

�Third: Radiologist and Nurse

• Hair, glasses, thyroid protector and mandil


LocalizationRadiologist

(Bq/cm2)

Nurse

(Bq/cm2)

Thyroid protector 17.6 -

Glasses - 12.2

Worse situation of contamination

22

Glasses - 12.2

Mandil 13.5 -

Hair 8.3 7.1

Cause: misplacement of the syringe

Solution:

� Washing under water flood

� Thyroid protector, mandil, and glasses retired (1day)


Results

Typical values of the procedure

Average Median

Irradiated volume(cm3)

919 575

23

(cm3)919 575

Pulmonar shunt(%)

11.5 11.7

Prescription dose(Gy)

115 120

Lung dose(Gy)

14.5 5.1

Y-90 activity fortreatment

(GBq)2.47 1.69


Index



Results

� Dose indicators

24

� Dose indicators





Emergency

Conclusions


Emergency

Patient needed emergency surgery

Non –expose workers

Variable number of professionals involved

25

Variable number of professionals involved

Irradiation risk

Contamination risk

High activities

Risk of deterministic effects for the staff


Irradiation risk:

During all the intervention

Photons

Contamination risk:

During all the intervention

Beta emission

RISKS

26

Photons

Low dose rate

� In contact

� 1 meter

No risk of deterministic effects

Estimation < 1mSv

Beta emission

High activities

�Blood

�Liver

Risk of deterministic effects

Rules


Contamination risk

� Mayor serious risk in contact with the liver

� Estimation with Varskin 3

� Average parameters

• Volume

27

• Volume

• Activity

�Sphere model

�Use of surgery gloves

�No gap


Erythema risk (2Gy)

Time after

administration

(h)

Contact dose rate

with Y-90 volume

(Gy/h)

Time to onset

deterministic effect

2Gy

(h)

Contact dose rate

with Y-90 volume

per MBq

(Gy / MBq h)

0 0.32 6.25 0.13

2 0.31 6.39 0.12

28

2 0.31 6.39 0.12

4 0.31 6.53 0.12

6 0.30 6.67 0.12

10 0.29 6.96 0.11

12 0.28 7.12 0.11

24 0.25 8.10 0.10

36 0.22 9.23 0.09

48 0.19 10.50 0.08

72 0.15 13.62 0.06

96 0.11 17.65 0.05


Index



Results

� Dose indicators

29

� Dose indicators





Emergency

Conclusions


Conclusions

Treatments with contamination risk

Higher contamination risk with Tc-99m thanks to the kit of Y-90 injection

Medical physicist involved in the whole process

30

Medical physicist involved in the whole process

There is an established protocol

Registration of dose indicators

Radiological Protection rules for staff, patients and families

Emergency protocol

Muchas graciasMuchas graciasMuchas graciasMuchas gracias




Análisis radioprotector de los

procedimientos diagnósticos y terapéuticos

con radioisótopos.

Directiva Euratom 59/2013

Aplicación a tratamientos de

tumores hepáticos con tumores hepáticos con

microesferas de Y-90



DANIEL PRIETO MORÁN

DANIEL PRIETO MORÁN - SEFM · T1/2 = 64h (2.67 d) Tissue range: 11 – 2.5 mm. Análisis...

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