BAB IV HASIL DAN PEMBAHASAN
4.8 Perhitungan TPR pada Energi Foton 10 MV Siemens dan
Untuk foton berenergi tinggi yang dihasilkan oleh akselerator klinis kualitas berkas ditentukan oleh tissue phantom ratio (TPR20 ,10
TPR
). Ini adalah rasio dari dosis yang diserap pada kedalaman 20 cm dan 10 cm di water phantom, diukur jarak sumber dengan detektor konstan 100 cm dan ukuran lapangan 10 cm x 10 cm di bidang ruangan.
20,10 dapat diperoleh dari hubungan PDD20,10 (Followil et. al., 1998) adalah:
TPR20,10 = 1,2661PDD20,10 - 0,0595 (2.17)
PDD20,10
Persamaan empiris ini diperoleh dari sampel hampir 700 akselerator dan telah mengkonfirmasi formulasi sebelumnya digunakan dalam TRS-277(IAEA, 1997).
adalah perbandingan presentase dosis pada kedalaman 20 cm dan kedalaman 10 cm untuk ukuran lapangan 10 cm x 10 cm pada permukaan phantom dengan SSD 100 cm.
Dari hasil pengukuran PDD energi foton 10 MV pada pesawat Siemens M5782 terdapat di Lampiran 6, pada kedalaman 20 cm distribusi dosis diperoleh sebesar 47,9, pada kedalaman 10 cm distribusi dosis diperoleh sebesar 73,5 %,
Sesuai rumus TPR20,10 = 1,2661PDD20,10 - 0,0595 diperoleh TRP pada energi foton 10 MV Siemens sebesar 0,75 % sesuai Lampiran 7.3.
Sedangkan dari hasil pengukuran PDD energi foton 10 MV pada pesawat Elekta terdapat di Lampiran 6, pada kedalaman 20 cm distribusi dosis diperoleh sebesar 45,94, dan kedalaman 10 cm distribusi dosis diperoleh sebesar 73,27%,
Sesuai rumus TPR20,10 = 1,2661PDD20,10
Dari hasil yang diperoleh TPR 10 MV Siemens sebesar 0,75%, sedangkan TPR 10 MV Elekta 0,73% maka terdapat perbedaan
- 0,0595 diperoleh TRP pada energi foton 10 MV Elekta sebesar 0,73% sesuai Lampiran 7.4.
75 , 0
73 ,
0 x 100 % = 0,97%
dengan standard BATAN yang diperbolehkan sebesar 3%.
BAB V PENUTUP
5.1 Kesimpulan
Dari hasil penelitian “Perbandingan Indeks Kualitas Energi Foton Pada Pesawat Linac Siemens Dan Elekta Dengan Metode Precentage Depth Dose (PDD) dan Metode Tissue Phantom Ratio (TPR) diambil kesimpulan sebagai berikut :
1. Pada energi foton 6 MV metode PDD, Dmax Pesawat Linac Elekta lebih besar sejumlah 0,94% dibandingkan Dmax Pesawat Linac Siemens, sesuai hasil penelitian Dmax Pesawat Linac Siemens terdapat pada kedalaman 15 mm sedangkan Elekta terdapat pada kedalaman 16 mm dan pada energi foton 10 MV metode PDD, Dmax Pesawat Linac Elekta lebih besar sejumlah 0,95%
dibandingkan Dmax Pesawat Linac Siemens, sesuai hasil penelitian Dmax
2. Pada energi foton 6 MV metode Tissue Phantom Ratio (TPR), TPR Pesawat Linac Elekta lebih besar 0,98%, sesuai hasil penelitian diperoleh TPR Pesawat Linac Siemens diperoleh 0,66% sedangkan Pesawat Linac Elekta 0,67 % dan pada energi foton 10 MV metode Tissue Phantom Ratio (TPR), TPR Pesawat Linac Siemens lebih besar 0,97%, sesuai hasil penelitian TPR Pesawat Linac Siemens diperoleh 0,75% sedangkan Pesawat Linac Elekta 0,73 % (standar BATAN yang diperbolehkan sebesar 3%).
Pesawat Linac Siemens terdapat pada kedalaman 20 mm sedangkan Elekta terdapat pada kedalaman 21 mm (standar BATAN yang diperbolehkan sebesar 3%).
3. Dari penelitian yang telah dilakukan pada pesawat Linac Siemens dan Elekta dapat disimpulkan bahwa:
a. Energi foton 6 MV metode PDD Pesawat Linac Elekta lebih baik dari Siemens dan energi foton 10 MV metode PDD Pesawat Linac Elekta lebih baik dari Siemens, namun masih dalam batas toleransi dibawah 3%
sesuai standar BATAN 3%.
b. Energi foton 6 MV metode TPR Pesawat Linac Elekta lebih baik dari pesawat Linac Siemens dan energi foton 10 MV metode TPR Pesawat Linac Siemens lebih baik dari Elekta, namun masih dalam batas toleransi dibawah 3% sesuai standar BATAN 3%.
c. Disimpulkan Pesawat Linac Siemens dan Elekta dinyatakan layak pakai.
5.2 Saran
Berdasarkan kesimpulan penelitian maka penulis merekomendasikan saran sebagai berikut :
a. Berharap dilakukan penelitian selanjutnya dibandingkan dengan pesawat Linac lebih dari 2 unit pesawat dengan merek yang berbeda.
b. Berharap penelitian selanjutnya dengan pesawat Linac lebih dari 2 unit dengan tahun yang sama dan jumlah pasien yang sama.
DAFTAR PUSTAKA
Anonim, 2003, Digital Accelerator Instalation, Electa Limited, no.
4513370187105 (08.03), Electa Limited Linac House Flaming Way, Red Crawley West Sussex RH109RR, UK. 6-30
Anonim, 1996, Central axis depth dose data for use in Radiotherapy, British Journal Radiologi, Supplement no. 25, The British Institute of Radiology, London.
Alam M. J., Rabbani Z., Hussain A., Baig A. K. V., 2007, A modified formula for defining tissue phantom ratio of photon beams, Bangladesh Medical Research Council. 33: 92-97
Butson M. J., Cheung T., Yu P., 2002, Calculation of electron contamination doses produced using blocking trays for 6 MV X-rays, Pegamon, Department of Physics and Materials Science, City University of Hong Kong. Radiation Measurements 35 : 99–102
Buzdar S. A., Rao A., Aalia N., 2009, An Analyis 0f Depth Dose Charateristik of Photon in Water, Journal Ayub Med Coll Abbottabad, The Islamia University, Bahawalpur, Pakistan. 21(4)
Chen C., 2007, Principles and requirements of external beam dosimetry, Elselvier,Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA.S2 – S21
Followill D.S., Toilor R.C., Tello V.M., Hanson W.F., 1998, An empirical relationship for determining photon beam quality in TG-21 from a ratio of percent depth doses, Med Phys. 25 : 1202-1205.
IAEA, 1997, Absorbed Dose Determination in Photon and Electron Beams: An International Code of Practice, Technical Report Series, TRS-277, IAEA, Vienna, Austria.
IAEA, International Atomic Energy Agency, 2000, Absorbed Dose Determination in External Beam Radiotherapy : An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water, International Atomic Energy Agency, Technical Reports Series, TRS-398, IAEA, Vienna, Austria. (62-63, 157-164)
Khan F. M., 2003, Title : Physics of Radiation Therapy, The 3rd Edition, Lippincott Williams & Wilkins, Philadelphia, USA(136-137,164)
Kriˇzan P., Rihard H., 2008, Teleradiography Dose Calculation, Faculty of Mathematics and Physics, University of Ljubljana.
Li G., Huaqing Z., Guangyao S. and Wu Y., 2011, Photon Energy Spectrum Recontruction Based on Monte Carlo and Measured Precentage Depth Dose in Acurate Radiotheraphy, Institut Plasma Physic,Chinese Academy of Science, China.Vol. 2, pp.160-164
Natto S. A., 2007, A Comparative Study of Measured Percentage Depth Doses for two Medical Linear Accelerators, Umm Al-Qur a Univ. Journal Science Med. Eng, Saudi Arabi.Vol.19,No.2, pp.145 -151
Podgorsak E.B., 2005, Radiation Oncology Physics: A Handbook for Teachers and Students, International Atomic Energy Agency, Technical Editor, Vienna.Thirth Edition.(179-191)
Richmond N., Robert B., 2014, A Comparison of Small-Field Tissue Phantom Ratio Data Generation Methods for an Elekta Agility 6 MV Photon Beam, Elsevier, Medical Physics Department, The James Cook University Hospital, Middlesbrough, United Kingdom.60-63
Suharni, Kusminarto, Diah F.I., Aggraita P., 2012, Perhitungan Eefisiensi Daya Berdasarkan Presentase Kedalama Dosis (PDD) pada Linac Medis RS dr.
Sarjito, Program Pasca Sarjana Fisika – UGM, PTAPB – BATAN, Yogyakarta. Volume 14. ISSN 1411-1349
Ślosarek K., Agata R., 2005, Comparison of Percent Depth Doses for Various Linear Accelerators, Journal Medical Physics Eng, Polandia. 11(1):39-50.
PL ISSN 1425-4689
Sardari D., Maleki R., Samavat H., Esmaeeli A., 2009, Measurement of depth-dose of linear accelerator and simulation by use of Geant4 computer code, Elselvier, Department of Medical Physics, Hamadan University of Medical Science, Hamadan, Iran. Reports of practical oncology and radiotherapy 15 (2010)64–68
Tammasebi B., Karbalaee, 2009, Calculation of Expressieon for Measured Precentage Depth Dose Data in Megavoltage Photon Theraphy, Iranian Red Crescent Medical Journal, Iran
LAMPIRAN 1. GAMBAR ALAT DAN BAHAN
1.1. Pesawat Linac Siemens dan Phantom Air
1.2 Pesawat Linac Elekta dan Phantom Air
1.1.1. Chamber Farmer Siemens 1.2.1. Chamber Farmer Elekta
1.1.2. Elektrometer Siemens 1.2.2. Elektrometer Elekta
1.1.3. Meja kontrol Siemens
1.2.3. Elektrometer Elekta
LAMPIRAN 2. HASIL PENGUKURAN POLARISASI TEGANGAN
Tabel 2.1 Hasil pengukuran polaritas tegangan pesawat Linac Siemens dengan dosis energy = 200 MU (Monitor Unit)
Tabel 2.2 Hasil pengukuran polaritas tegangan pesawat Linac Elekta Dengan dosis energy = 200 MU (Monitor Unit)
LAMPIRAN 3. TABEL TRS 398
Tabel 3.1. TRS 398 Pesawat Linac Siemes 6 MV
User: Date:
1. Radiation treatment unit and reference conditions for Dw,Q determination Accelerator:
Nominal Acc Potential: 6 MV
Nominal dose rate: 200,0 MU min-1 Beam quality, Q (TPR20,10) 0,670
Reference phantom: water Set up:
Reference field size: 10 x 10 cm cm x cm Reference distance: 100 cm
Reference depth zref : 10,0 g cm-2
2. Ionization chamber and electrometer
Ion. chamber model Serial No.:
Chamber wall material: graphite thickness: 0,068 g cm-2
Waterproof sleeve material: thickness: g cm-2
Phantom window material: thickness: g cm-2
Abs. dose-to-water calibration factor a
Calibration quality Q0: Calibration depth: g cm-2
If Q0 is photons, give TPR20,10:
Reference conditions for calibration
P0: 101,3 kPa T0: 20,0 °C Rel. humidity: 50 %
Polarizing potential V1: 300 V
Calibration polarity:
User polarity:
Calibration laboratory: Date:
Electrometer model: Serial no.:
Calib. separately from chamber: Range setting:
If yes Calibration laboratory: Date:
3. Dosimetry reading b and correction for influence quantities
Uncorrected dosimeter reading at V1 and user polarity: 26,58
Corresponding accelerator monitor units: 200 MU
Ratio of dosimeter reading and monitor units: M1 = 0,1329
(i) P: 100,5 kPa T: 23,8 °C Rel. humidity: 42 % 1,021
(ii) Electrometer calibration factor kelec :
(iii) Polarity correction d rdg at +V1 M+ = 26,58 rdg at -V1: M- = 26,6
1,000
(iv) Recombination correction (two-voltage method)
Polarizing voltages: V1 (normal) = 300 V V2 (reduced) = 100 V
Corrected dosimeter reading at the voltage V1:
0,1362
4. Absorbed dose rate to water at the reference depth, zref Beam quality corr. factor for user quality Q : 0,9940 taken from Worksheet for the determination of the absorbed dose to water
in a high-energy photon-beam
15-Agust-16 0,05
Siemens Primus M5782
+ve -ve corrected for polarity effect
+ve -ve Wellhöfer IC 70 Farmer
Table 6.III Other, specify:
+ =
Tabel 3.2. TRS 398 Pesawat Linac Siemes 10 MV
User: Date:
1. Radiation treatment unit and reference conditions for Dw,Q determination Accelerator:
Nominal Acc Potential: 10 MV
Nominal dose rate: 300,0 MU min-1 Beam quality, Q (TPR20,10) 0,750
Reference phantom: water Set up:
Reference field size: 10 x10 cm x cm Reference distance: 100 cm
Reference depth zref : 10,0 g cm-2
2. Ionization chamber and electrometer
Ion. chamber model Serial No.:
Chamber wall material: graphite thickness: 0,068 g cm-2
Waterproof sleeve material: thickness: g cm-2
Phantom window material: thickness: g cm-2
Abs. dose-to-water calibration factor a
Calibration quality Q0: Calibration depth: 5 g cm-2
If Q0 is photons, give TPR20,10:
Reference conditions for calibration
P0: 101,3 kPa T0: 20,0 °C Rel. humidity: 50 %
Polarizing potential V1: 300 V
Calibration polarity:
User polarity:
Calibration laboratory: Date:
Electrometer model: Serial no.:
Calib. separately from chamber: Range setting:
If yes Calibration laboratory: Date:
3. Dosimetry reading b and correction for influence quantities
Uncorrected dosimeter reading at V1 and user polarity: 28,89
Corresponding accelerator monitor units: 200 MU
Ratio of dosimeter reading and monitor units: M1 = 0,1445
(i) P: 100,5 kPa T: 23,8 °C Rel. humidity: 42 % 1,021
(ii) Electrometer calibration factor kelec :
(iii) Polarity correction d rdg at +V1 M+ = 28,89 rdg at -V1: M- = 28,9
1,000
(iv) Recombination correction (two-voltage method)
Polarizing voltages: V1 (normal) = 300 V V2 (reduced) = 100 V
Corrected dosimeter reading at the voltage V1:
0,1480
4. Absorbed dose rate to water at the reference depth, zref Beam quality corr. factor for user quality Q : 0,9830 taken from
0,0073 Gy / MU in a high-energy photon-beam
15-Agust-16
+ve -ve corrected for polarity effect
+ve -ve Wellhöfer IC 70 Farmer
Table 6.III Other, specify:
+ =
Tabel 3.3. TRS 398 Pesawat Linac Elekta 6 MV
User: Date:
1. Radiation treatment unit and reference conditions for Dw,Q determination Accelerator:
Nominal Acc Potential: 6 MV
Nominal dose rate: 500,0 MU min-1 Beam quality, Q (TPR20,10) 0,680
Reference phantom: water Set up:
Reference field size: 10x10 cm x cm Reference distance: 100 cm
Reference depth zref : 10,0 g cm-2
2. Ionization chamber and electrometer
Ion. chamber model Serial No.:
Chamber wall material: PMMA thickness: 0,057 g cm-2
Waterproof sleeve material: thickness: g cm-2
Phantom window material: thickness: g cm-2
Abs. dose-to-water calibration factor a
Calibration quality Q0: Calibration depth: 5 g cm-2
If Q0 is photons, give TPR20,10:
Reference conditions for calibration
P0: 101,3 kPa T0: 20,0 °C Rel. humidity: 60 %
Polarizing potential V1: 400 V
Calibration polarity:
User polarity:
Calibration laboratory: Date:
Electrometer model: Serial no.:
Calib. separately from chamber: Range setting:
If yes Calibration laboratory: Date:
3. Dosimetry reading b and correction for influence quantities
Uncorrected dosimeter reading at V1 and user polarity: 25,33
Corresponding accelerator monitor units: 200 MU
Ratio of dosimeter reading and monitor units: M1 = 0,1267
(i) P: 1015,0 kPa T: 20,2 °C Rel. humidity: 49 % 0,100
(ii) Electrometer calibration factor kelec :
(iii) Polarity correction d rdg at +V1 M+ = 25,33 rdg at -V1: M- = 25,35
1,000
(iv) Recombination correction (two-voltage method)
Polarizing voltages: V1 (normal) = 400 V V2 (reduced) = 100 V
Corrected dosimeter reading at the voltage V1:
1,2677E-02
4. Absorbed dose rate to water at the reference depth, zref
Beam quality corr. factor for user quality Q : 0,9900 taken from
6,6393E-04 Gy / MU 2923 LAZ/TATY
BATAN
25/02/2017 Worksheet for the determination of the absorbed dose to water
in a high-energy photon-beam
17-Okt-16 0,0529
Elekta Precise Treatment System
+ve -ve corrected for polarity effect
+ve -ve
Table 14 Other, specify:
+ =
Tabel 3.4. TRS 398 Pesawat Linac Elekta 10 MV
User: Date:
1. Radiation treatment unit and reference conditions for Dw,Q determination Accelerator:
Nominal Acc Potential: 10 MV Nominal dose rate: 477,0 MU min-1 Beam quality, Q (TPR20,10) 0,730
Reference phantom: water Set up:
Reference field size: 10x10 cm x cm Reference distance: 100 cm
Reference depth zref : 10,0 g cm-2
2. Ionization chamber and electrometer
Ion. chamber model Serial No.:
Chamber wall material: PMMA thickness: 0,057 g cm-2
Waterproof sleeve material: thickness: g cm-2
Phantom window material: thickness: g cm-2
Abs. dose-to-water calibration factor a
Calibration quality Q0: Calibration depth: 5 g cm-2
If Q0 is photons, give TPR20,10:
Reference conditions for calibration
P0: 101,3 kPa T0: 20,0 °C Rel. humidity: 60 %
Polarizing potential V1: 400 V
Calibration polarity:
User polarity:
Calibration laboratory: Date:
Electrometer model: Serial no.:
Calib. separately from chamber: Range setting:
If yes Calibration laboratory: Date:
3. Dosimetry reading b and correction for influence quantities
Uncorrected dosimeter reading at V1 and user polarity: 27,42
Corresponding accelerator monitor units: 200 MU
Ratio of dosimeter reading and monitor units: M1 = 0,1371
(i) P: 1015,0 kPa T: 20,2 °C Rel. humidity: 49 %
0,100
(ii) Electrometer calibration factor kelec :
(iii) Polarity correction d rdg at +V1 M+ = 27,42 rdg at -V1: M- = 27,44
1,000
(iv) Recombination correction (two-voltage method)
Polarizing voltages: V1 (normal) = 400 V V2 (reduced) = 100 V
Corrected dosimeter reading at the voltage V1:
1,3744E-02
4. Absorbed dose rate to water at the reference depth, zref
Beam quality corr. factor for user quality Q : 0,9820 taken from
7,1399E-04 Gy / MU 2923 RSUP Adam Malik
BATAN
25/02/2017 Worksheet for the determination of the absorbed dose to water
in a high-energy photon-beam
17-Okt-16 0,0529
Elekta Precise Treatment System
+ve -ve corrected for polarity effect
+ve -ve
Table 14 Other, specify:
+ =
LAMPIRAN 4. SERTIFIKAT KALIBRASI OUTPUT DAN DOSIMETER SIEMENS DAN ELEKTA
LAMPIRAN 5. DATA MENTAH PENELITIAN
327,9 19.40
239,9 31.24
152 50.70
63,9 81.03
TABEL 5.2. DATA MENTAH PERCENTAGE DEPTH DOSE (PDD)
321,9 26.83
233,9 40.33
145,9 60.36
57,9 89.95
TABEL 5.3. DATA MENTAH PERCENTAGE DEPTH DOSE (PDD) PHOTON 6 MV ELEKTA
323,9 19.82
235,9 31.91
TABEL 5.4. DATA MENTAH PERCENTAGE DEPTH DOSE (PDD) PHOTON
55,9 90.52
LAMPIRAN 6. DATA PENELITIAN
Tabel 6.1 Data hasil penelitian PDD dan TPR 6 MV Siemens
Depth
Tabel 6.2 Data hasil penelitian PDD dan TPR 10 MV Siemens Depth
(mm)
PDD (%) 10 MV
Siemens TPR 10 MV Siemens
0 32,84 No. Seri
Tabel 6.3 Data hasil penelitian PDD dan TPR 6 MV Elekta
Tabel 6.4 Data hasil penelitian PDD dan TPR 10 MV Elekta
TPR 10 MV ELEKTA
Tabel 6.5 Data hasil penelitian PDD Siemens dan Elekta 6 MV Siemens Elekta
0 47,85 47,85
Tabel 6.6 Data hasil penelitian PDD Siemens dan Elekta 10 MV Depth
Siemens Elekta
0 32,84 47,85
LAMPIRAN 7 PERHITUNGAN TPR
LAMPIRAN 7.1 PERHITUNGAN TPR 6 MV SIEMENS Rumus TRS 2.13 (IAEA 2000) yaitu
* TOR 20,10 = 1,2661PDD2010, - 0,0596
LAMPIRAN 7.2 PERHITUNGAN TPR 6 MV ELEKTA Rumus TRS 398 yaitu
LAMPIRAN 7.3 PERHITUNGAN TPR 10 MV SIEMENS
LAMPIRAN 7.4 PERHITUNGAN TPR 6 MV ELEKTA Rumus TRS 398 yaitu